Cold Weather Operations

EA-I. (Palmer W. Roberts)

COLD WEATHER OPERATIONS

        Increased activity in the arctic region has focused attention on the

engineering problems encountered. In considering cold weather operations, it

would be hard to find a field of human knowledge in which the past reveals so many

practical guideposts for the present and upon which plans can be made for the

future.

        Operations in the Arctic and Subarctic do not vary greatly from those

in the North Temperate zone. There are, however, certain variations in field

practices, construction methods, and engineering design necessary to meet the

requirements imposed by climate, terrain, and other local factors. In approach–

ing such problems, the peculiarities of the area must be accepted and the usual

design, materials, and construction techniques modified accordingly. The effi–

cient and effective use of all resources and conditions in the Arctic must

greatly influence the application of all engineering principles. It is necessary

to work with nature and not against her in the Arctic.

        In the space assigned the subject of engineering in the Encyclopedia

Arctica , it would not be possible to cover the many subjects in the fields of

engineering for each country or area where special problems may be encountered.

It has, therefore, been necessary for the authors to treat many of the subjects

only in specific areas. In the main, the articles are concerned with operations

in the northern regions of the North American continent. However, the princi–

ples and techniques discussed may serve as a guide for other areas, after

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EA-I. Roberts: Cold Weather Operations

analyzing local conditions.

        In planning for operations in the Arctic, logistics, or providing the

means for supporting and accomplishing the task, may often prove to be the

limiting factor. The absence of rail and road nets, the difficulty of move–

ment overland both in winter and summer, the lack of ice-free ports in the

winter and the short period in the summer when vessels may operate, and the

limitations imposed on flying by poor visibility near bodies of water during

certain periods of the year, are a few of the many factors relating to the

area which must be considered. The maintenance and operation of equipment

under the variety of conditions imposed by extreme weather and terrain, and

the providing of at least the minimum of bodily comfort in the manner of

clothing and shelter for personnel, as well as proper food and adequate train–

ing, are problems that must be solved for each operation.

        A thorough knowledge of the physical character of the Arctic during

all seasons of the year is also essential to the success of any operation

(see “Work Feasibility”). Surface and subsurface conditions vary greatly

with the season in the Arctic. Vast quantities of ice form in the winter

and much of it remains in the seas during the summer. The presence of ice as

a rock, or as a rock constituent of frozen ground, presents a major subsurface

problem for study (see “Permafrost”).

       

Palmer W. Roberts

Work Feasibility

EA-I. Roberts; Work Feasibility

       

LIST OF FIGURES

		Page
Fig. 1.	Work feasibility chart	5-a

001      |      Vol_IIA-0287                                                                                                                  
EA-I. (Palmer W. Roberts)

       

WORK FEASIBILITY

        In the northern regions and seasonal variations in climate and terrain

are extreme, yet the cold does not establish a barrier for human activity.

Climatic conditions do become a major factor when dealing with problems in

design and construction engineering. Climate has been said to be the annual

or long-term result of weather, and weather the result of nature’s effort to

balance the heat equation of the hemisphere. To provide a general background

of weather as it relates to engineering in the northern regions, major climate

factors - temperature, wind, precipitation, visibility, and light - are briefly

discussed herein.

        Temperature . In the northern areas great temperature differences prevail.

The coldest temperature ever recorded in the northern regions was at Verkhoiansk,

Siberia, where −93.5°F. was reported. The lowest temperature in North America

ever recorded was −81°F. at Snag. Yukon Territory. Fort Yukon, just north of

the Arctic Circle in Alaska, has a U.S. Weather Bureau record of 100°F. in the

shade and considerably higher extremes have been reported at several places in

the North American and European Subarctic. Thus, it is apparent that the extreme

temperature range (Fahrenheit) for the Arctic can be placed at approximately

195 degrees; in Alaska the spread is approximately 185 degrees.

        Wind . The frequency and velocity of high winds in the Arctic is are not as ✓

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EA-I. Roberts: Work Feasibility

great as in the other zones. Stronger winds, and more frequent strong winds,

are experienced in the winter along the coast than are found in the interior

at that time; in summer the differences are not so great. The frequency of

strong winds in the North American Arctic resembles that of Siberia. At

Point Barrow, Alaska, the maximum velocity so far recorded (up to 1950) for

the winter months is something over 100 m.p.h. but for the summer only 41 m.p.h.,

with the average annual mean at 12 m.p.h.

        Precipitation is light in the Arctic. The annual total of melted snow

and rain may not exceed 10 inches per year in most of the Alaska and Canadian

Arctic, and is probably even less in the Soviet Arctic. It is difficult to

obtain accurate measurements of snow, due to the light and fluffy nature of

the crystals and their tendency to migrate under less than average wind velocity.

Snow may fall in any month. In the winter the precipitation is mainly in the

form of snow and is generally very light, except that fairly heavy snowfall occurs

in certain foothill and mountain areas. At Point Barrow, where accurate

aerological measurements are maintained throughout the year, the maximum snowfall

occurs in October, eight inches having been recorded during this month. Very

light rains are experienced throughout the Arctic in the summer, with the

maximum occurring during July and August. Thunder is rare.

        Visibility . Fog and poor visibility provide difficulties for arctic

operations and ofttimes limit e a viation and ship operations along the coast. ✓

Fogs are usually most dense at the borders of the ice. The land senses of

the Arctic are warmer than the sea in the summer and colder in the winter.

Thus winds passing from either belt across the other are liable to produce fog.

The most severe fog conditions are experienced in spring and in the fall

when a visibility of a mile or less occurs more than 20% of the time. Cloudless

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days (0 to 0.2 coverage) are not common along the arctic coasts, but do occur

during December and January, the clearest months.

        Light is a rather peculiar problem is polar regions; it is received from

the direct and refracted rays of the sun, the moon, the stars, the planets,

and from the aurora borealis. The sun remains above the horizon, because of

refraction, for something over six months at the Pole, nearly four and one-half

months at 80° N., and for over eighty days at Point Barrow, 71°23′ N. It is

never pitch dark at night in the North and there is more effective light in

these areas than in the tropics or temperate zones. This is because of

several factors, namely:

1. Cold, clear, dust-free air transmits light more readily.
   
   
2. During the period of no direct sunlight, the snow and ice cover
   
   reflects and magnifies all light that it receives from the various light sources.
   
   
3. When the ground is not covered with snow, there is perpetual direct
   
   and reflected sunlight.
   
   
4. The starts, moon, and aurora succeed in delivering a high percentage
   
   of their produced light to the earth during the winter.
   
   

        Maximum arctic darkness occurs in winter when the sky is densely overcast,

when there is no moon or twilight, and when there is no aurora behind the

clouds. However, even under such maximum darkness conditions, a man clad in

dark clothing can be seen a distance of about one hundred yards against a

snow or ice background. In winter the aurora borealis display is frequent;

in the summer it can be seldom be seen because of continuous light. They Auroras are of ✓

varied description and undergo rapid changes in form. Some of these forms may

be described as arcs, rays, streaks or lances, bands, curtains or draperies,

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EA-I. Roberts: Work Feasibility

coronas, diffused light, crowns, and cloud-shaped. They c v ary greatly in ✓

color (see “The Aurora Borealis”).

        The effect of the extreme variations in climate on engineering operations

can best be realized by comparing the physical character of the arctic surface

and subsurface during the extreme periods of winter and summer. Permanently

frozen ground, called permafrost, is a widespread phenomenon, common through–

out North America and northern Asia; about one-fifth of the land area of the

world is underlain by permafrost. Temperature within permafrost varies during

the year generally from 16° f t o 30°F. In the upper layer of the ground, which ✓

is not permanently frozen, the effects of seasonal thawing are usually more

severe than in areas not underlain by permanently frozen material. It has

been determined that stresses developed in freezing ground may exceed 28,000

pounds per square inch. When ground conditions established by nature are

disturbed during construction, the thermal equilibrium must be restored as

quickly as possible. Groundwater may exist in frozen or thawed ground and,

as migrating water transmits heat, many of the problems of freezing and thawing

are related to it. In winter, drifting snow creates many problems and, there–

fore, is always considered when selecting sites for building or routes for

freighting operations. In the summer, snow remains on the ground in lowland

areas for short periods only.

        Thickness of the ice on the rivers, on the lakes, and on the Arctic Sea,

is important in connection with transportation. In northern Alaska, ice begins

to form on fresh-water lakes early in September and on salt water usually the

latter part of the same month. Maximum thickness of ice is reached in early

May on both fresh- and salt-water bodies.

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        From even this brief description it can be deduced that the weather during

the major part of the year is such that detailed analysis of climatic factors

will be required before units can be committed to arctic field operations. The

principal factors to consider are as outlined: light, temperature, wind (the

combined wind-chill factor), precipitation (snow and rain), ceiling, visibility,

and the thickness of ice and other factors of sea condition. A comparison of

the above and of the work or mission to be accomplished is necessary. As an

aid in making such an evaluation, a chart of the factors may be of assistance

(see Fig. 1). On this chart are shown the factors of climate and the work or

mission to be accomplished, such as transportation, construction, and water

supply. Examining the month of February, the following factors are noted.

        Daylight: 3 hours increasing to 9 hours with an additional 1-1/2 hours

of twilight per day.

        Ceiling: 1,000 feet or lower, 19% of the month.

        Visibility: one mile or less, 14% of the month.

        Temperature: absolute maximum, 35°F; mean maximum −15°; mean tempera–

ture, −20°; mean minimum −25°; absolute minimum −56°.

        Wind: maximum recorded, 71 miles per hour; average, 10 miles per hour;

direction SW. 43%, NE. 15%.

        Wind chill: varying from B, fair for traveling, to E, extreme limit

for operations.

        Precipitation: 4 inches of snow; trace of rain.

        New ice thickness: ocean, 40 inches increase to 50; lakes and rivers,

48 inches increase to 54.

        Reviewing these it is noted that over-ice freighting with tractors and

sleds can be conducted. Ground surface will support wheeled vehicles, tractors,

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and sleds . can be conducted. Ground surface will support wheeled vehicles,

tractors, and sledo. Planes can operate on skis throughout the area and on

wheels from prepared strips. However, the number of flying hours per day is

limited by daylight (moonlight can be used for supplementary purposes for

several days either side of the full, if the sky is clear). Shallow lakes

and rivers will be frozen but water can be taken from deeper lakes or obtained

from melting ice or snow. Due to poor visibility and cold, surveying is not

recommended. Earth work is not possible at this season but foundation work

can be accomplished by the use of explosives or by thawing methods. For

outside construction work, flood lighting will be required. The month of

February could be utilized to repair equipment in shops and accomplish inside

construction. All equipment to be used out of doors will required complete

winterization, arctic lubricants and fuels, and heated inside storage.

Personnel will require adequate protection, proper clothing, and indoctrination.

        This same procedure, analyzing the climatic and operating factors, can

be followed for each month of the year. Charts of this type can easily be

developed for all parts of the polar, arctic, and subarctic regions and

should be made available for the planning of operations.

       

Palmer W. Roberts

Arctic Surveying

EA-I. (Ralph W. Woodworth)

ARCTIC SURVEYING

       

CONTENTS

	Page
Introduction	1
Preparation s for Arctic Surveys	2
Local Transportation	3
Surveys	4
Geodetic Control Surveys	4
Astronomical Observations	4
Base-line Measurements	5
Horizontal Control	5
Level Net	5
Station Marks	5
Topographic Surveys	6
Hydrographic Surveys	7
Hydrography	7
Tides	9
Magnetics	9
Conclusions	10
Bibliography	10

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LIST OF FIGURES

		Page
Fig. 1	Alaska triangulation net	10-a
Fig. 2	Alaska hydrographic surveys	10-b

001      |      Vol_IIA-0296                                                                                                                  
[EA:I. Ralph W. Woodworth]

       

ARCTIC SURVEYING

       

INTRODUCTION

        The special problems encountered in surveys of the land and water areas

of arctic regions are due to the raw or undeveloped nature of the country. The

land routes of communication, except in the vicinity of the larger settlements,

are primitive and the meteorological conditions are rigorous. Both combine

to limit activities, at present, to less than six months of the year. Winter

work is reduced to a minimum.

        Surveys in the Arctic are not difficult to accomplish. The subzero tempera–

tures are uncomfortable and the danger element is, of course, always present.

With careful planning, a knowledge of the country, experience with the limita–

tions of the various types of transportation, and the elimination of unneces–

sary risks, operations may be carried out safely and efficiently although at

high cost.

        The over-all success of a project is dependent to a considerable degree on

the detailed plans made for the project, as under the comparatively harsh condi–

tions of the Arctic, nothing may be left to chance. The selection of proper

transportation equipment is perhaps the greatest single factor that will con–

tribute to the success of a mission.

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        Surveys in subarctic regions are planned and accomplished in much the

same way as surveys in the temperate zones. These areas are more accessible

and weather conditions are milder than those of the Far North. Field methods

and instrumental equipment are similar to those used in the temperate regions.

       

Preparations for Arctic Surveys

        To achieve maximum efficiency in the short field season, the following

preparatory steps should be taken.

        1. Prepare comprehensive and detailed plans to cover every phase of

supply, administration, and operation well in advance of the beginning of the

project.

        2. Procure, test, and condition suitable rugged equipment and instruments

with spares of all items and a generous supply of spare parts.

        3. Insure and adequate supply of communication equipment.

        4. Ship the equipment to arrive well in advance of probable needs.

        5. Prior to departure from the continental base, instruct all personnel in

the nature of the proposed su s rveys, the character o the country, the special

care required for the equipment, and the methods of operation.

        Procurement, particularly for the specialized items, should be instituted

a year in advance of operations. Checks must be made to insure that items that

cannot be procured in the Arctic are in the hands of the survey party at least

two months before departure.

        Personnel should be transported from the continental area to the Arctic

by airplane on the following schedule which may be modified as weather conditions

permit.

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        1. Mid-January: liaison group to complete preliminary field arrangements.

        2. Early February: astronomic groups.

        3. Mid-February: chief of party and staff, plus geodetic (triangulation

observing) groups.

        4. Early June: balance of party.

        Good organization requires that each subparty shall be as nearly self–

sufficient as practical; that one reliable Eskimo familiar with the country

shall be included with each unit; that each observing group shall include an

extra observer; and that the specialists, the heavy equipment, labor pool, and

emergency transportation shall be under control of the headquarters group.

        Base camps should be selected at least two years in advance and supplemen–

tal camps one year.

        Plans must provided that mobile parties carry a full allowance of rations,

sleeping bags, and sample communication equipment. Radio schedules must be set

up and these schedules maintained.

       

Local Transportation

        Because of the undeveloped nature of the country, local field transporta–

tion requires limited support of both small and large airplanes, bulk-hauling by

tractor or sledge trains, and employment of small amphibious-type tracked vehicles.

Wheeled vehicles, unless ski-mounted, are nearly useless.

        Dog teams are useful in an emergency. The light pay load and the neces–

sity of carrying or securing food for the animals definitely limit their value.

The dog sledge is a very desirable article of equipment and may be trailed

behind weasels” or jeeps.

        Ship or launch transportation in the Arctic is limited to the few months of

open water.

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SURVEYS SURVEYS (delete underlining)

        Surveys in the Arctic comprise geodetic control surveys for the deter–

mination of geographical positions and elevations for use in charting and

mapping; topographic surveys from aerial photographs; and hydrographic surveys

for the determination of depths of water for navigation.

       

Geodetic Control Surveys

        Geodetic control surveys include astronomical observations for determina–

tion of the position of the starting point and initial azimuth; base-line measure–

ments; and horizontal observations of directions for extension of triangulation

or traverse.

        Astronomical Observations . Where possible, the starting point and initial

azimuth should be determined with precision. This can be done with standard

methods and equipment. Azimith may be obtained with a direction theodolite.

Where weight of instruments is a factor, satisfactory observations of latitude

and longitude may be obtained, using the “equal altitudes” method and the pris–

matic astrolabe.

        The best time for observations, especially above the Arctic Circle, is

during the hours of darkness in the early spring or late fall. Spring obser–

vations are made ordinarily in less time and more economically than fall obser–

vations because the skies are clearer and radio reception is better due to the

absence of the northern lights, although the temperature is lower.

        Above latitude 60°, special care must be taken in order to secure a satis–

factory value for azimuth because of the close spacing of the meridians. The

method outlined Hoskinson and Duerksen (7) for observations of this type will

yield excellent results.

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        The instruments used are sparingly oiled with a very fine watch oil and

tested to −50°F. in a cold chamber. Between observations they are placed in

unheated storage to prevent condensation and subsequent fogging of the lenses

and freezing of bearing surfaces. Glycerin rubbed on contact points will

effectively prevent freezing.

        Base-line measurements are more easily made over flat ground or the flat

ice of lakes or lagoons with the line laid out in the direction of the pre–

vailing wind. First-order accuracy may be obtained with standard methods.

Stakes should be steam-jetted into the ice or ground using a portable boiler.

        Horizontal control in the Arctic is extended by triangulation methods.

Triangulation is faster than traverse and will produce more points for the

same amount of effort.

        Standard triangulation observing methods as given by Hodgson (6) and in

another manual of the U.S. Coast and Geodetic Survey (15) have been found

to be the most economical methods for daylight work in the Arctic.

        The observing period begins when there is sufficient light to warrant plac–

ing the observing groups in the field and ends when the combination of spring

thaw, making travel dangerous, and melting of snow, which produces excessive

refraction, render operations uneconomical. North of the Arctic Circle this

period extends, normally, from February to May or June.

        Level Net . Except for the lines of spirit levels along the Alcan Highway

and the Alaska Railroad, elevations have been determined by trigonometric

leveling. Such elevations may at times be subject to errors due to excessive

vertical refraction varying over the period of the level run.

        Station Marks . In subarctic regions, including the Aleutian chain, stations

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are marked with brass disks set into a drill hole in rock or into a concrete

block buried in the ground. In the higher latitudes where the permafrost

is close to the surface, the best marks are brass disks brazed to an iron

pipe steam-jetted into the ground.

       

Topographic Surveys

        Aerial photographic methods provide the best means of obtaining topo–

graphic data. Ground methods are useful only for fill-in. The photographs

are controlled by a tie between ground features and stations established by

triangulation.

        Photographic and field inspection operations are confined to a very short

period of the year. To secure accurate information, the ground must be photo–

graphed and the field inspection made when snow is at a minimum and the shore

line is clear of ice. In the Far North the best time has been found to be

during July and August and in the subarctic regions in the spring or late fall.

        The long shadows cast by the sun interfere with and often obscure detail

on slopes. This condition is minimized by taking photographs, where possible,

when the sun is at its maximum declination but there is no satisfactory

solution to the problem. Elevations supplemental to those obtained by leveling

may be obtained by means of the phototheodolite.

        The best and quickest method of spotting control for the field inspection

parties is to furnish them with low- or medium-al [ ?] titude verticals and obliques

in the vicinity of the stations. Methods which involve the use of ground

transportation may be used when more economical. When topography is not car–

ried out simultaneously with control, each station must be inspected on the

ground.

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Hydrographic Surveys

        Hydrography . Standard field methods, as outlined by Adams (1), are

suitable for arctic surveys. The principal problems are not technical in

nature but have to do with the full utilization of the short working season

and the selection of the best available equipment. The plans should provide

that all preliminary work, such as preparation of the sheets and overhaul

and conditioning of the equipment and instruments, will be completed well

in advance of the probable date of arrival of open water, so that hydro–

graphic operations may be commenced without delay.

        The hydrographic signals are built and located [ ?] by the triangula–

tion part as it progresses. On a resurvey they may be located by graphic

means or photogrammetric methods, either of which yields satisfactory results.

        Several types of boats have been used in the Arctic. The Navy rearming

boats are 35-foot diesel-powered single-screw wooden launches with enclosed

cabins and are capable of 12-15 knots speed. The landing craft are of various

types. The LCVP (Landing Craft Vehicle Personnel), a diesel-powered single–

screw wooden boat with open cockpit and ramp bow, is capable of 8-12 knots

speed, but is a very wet boat in a seaway. The LCM (Landing Craft Mechanized),

a 50- or 56-foot diesel-powered, twin-screw, steel boat with open cockpit

and ramp bow, is capable of 8-10 knots, and is a reliable craft.

        Modifications to fit the boats for efficient use include: construction of

a shelter for the hydrographic crew on open-cockpit boats; removal, in some

cases, of the top of the ramp flush with the coaming of the boat to improve the

visibility; installation of strainers designed to keep slush out of the

engine on raw water cooling systems, or replacement of this type with keel

condenser systems; installation of metal sheathing along the water line for

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wooden boats in order to protect the hull from “young” ice; replacement of

Au: OK? the magnetic compass with a magnesyn-type compass; and application of a coat

of orange paint for easy identification. In addition to hull and engine

modifications, provision must be made for installation of the sounding and

radio apparatus. Each boat should be fitted with two Fathometers, an out–

board and inboard projector, and a two-way radio. Emergency rations and

sleeping bags for all personnel should be carried at all times.

        The best method of developing an area is by lines parallel to the beach.

Such a system provides maximum coverage with least cost. Every effort should

be made to complete one area before progressing to the next. For maximum

safety, boats must work in pairs and remain in close proximity, one sound–

ing out an offshore line while the other works along an inshore line. A

fully equipped spare launch should be available in each camp.

        The launches should never enter a lead in the ice, but if caught, the

landing craft should pick out a shelving section of ice and allow the boat

to be pushed upon it. Conventional boat types should tow a light dory and

carry two outboard motors.

        When ice is drifting on the shore, it will ground in water deeper than

the draft of the launch so that generally the boat may find open water close

to shore. In open ocean areas, if the wind picks up, the launches must get

through an inlet before the ice or breakers close it.

        Experience to date has indicated that the period from mid-July to mid–

September is the most suitable for hydrography in arctic water, but this

period is subject to wide variations from year to year. In the Aleutians,

the period from May to October is best.

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        Tides . The tide gages must be established prior to commencement of

hydrography. The types in common use are described in a special publication

of the U.S. Coast and Geodetic Survey (16). The portable automatic gage is

the only practical type for these areas unless a plain staff gage is estab–

lished for a short series of observations.

        At Point Barrow, the normal tide is small — a daily range of less than

a foot. The wind effect is much greater and has been recorded as reaching

3 feet. Winds blowing along the coast northerly and easterly from Point

Barrow lower the water level at Point Barrow, while winds from the opposite

direction raise it.

        Because of the small range of tide, gages are visited frequently and

the marigrams changed every 48 hours. The staff is checked at each visit

and revealed when damage is suspected.

        If necessary to build a gage on the ice, it may be done in the follow–

ing fashion: Erect a plain staff in a suitable position, make a hole through

the ice, and insert a pipe (4 inches in diameter or larger) filled with oil.

Pass a wire through the pipe and anchor it to the bottom, lead the free end

through a sheave on or near the top of the staff and down in front of the

staff. Secure a weight to it which will serve to keep the wire taut and to

indicate the depth. As the tide rises and falls the weight will register

on the graduated staff.

        Magnetics . In subarctic regions where the magnetic field is sufficiently

strong to orient the needle quickly, standard methods, as outlined by Hazard (5),

may be used.

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        In the Arctic no comprehensive magnetic surveys have been made. It is

doubtful if any great coverage of this region may be made until air-borne

operations are feasible. In this area, the horizontal component (declination)

of the earth’s magnetic field is weak and displays complexities and variations

that are neither well mapped nor well understood.

        Instruments must be especially calibrated for the magnetic latitude when

used in high arctic regions. Observations are impeded by the length of times

required to dampen the oscillations of the needle and by frequent unpredict q a ble ✓

magnetic storms.

       

Conclusions

        Progress in surveying and mapping in the Arctic will be accelerated by the

increasing interest in the region, by increased efficiency due to the probabl y e ✓

introduction of more efficient methods of surveying such as Shoran, and the

longer field season that will result as knowledge of the region increases.

        The att c ac hed sketches (Figs. 1 and 2) show graphically the progress that ✓

has been made by the U.S. Coast and Geodetic Survey in Alaska in the fields

or triangulation and hydrography through 1948. It is apparent that although

the progress during the last 50 years has covered a large proportion of the

most accessible part, a vast area still remains to be done.

---

BIBLIOGRAPHY

1. Adams, K.T. Hydrographic Manual . Wash., D.C., G.P.O., 1942. U.S. Coast &

Geodetic Surv. Spec.Publ . no.143. Rev. (1942) ed.

2. American Society of Photogrammetry. Manual of Photogrammetry . N.Y.,

Chicago, Pitman, 1944.

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---

3. ✓ k Drygalski, Erich von. Die Deutsche Südpolar-Expedition. Ber lin, Mitller,

(1902-03) 3v. in 2. Berlin. Univ.Inst. für Meeresk. Veröff . H.1-2, 5.

4. ✓ Great Britain. Royal Air Fo r ce. Empire Air Navigation School. Report no.45/24.

✓ 2 North Polar Flight of “Aries. ” 1946. 10 pts. Especially pt.10,

sect.5, “Terrestrial magnetism and magnetic compass in the Arctic.”

5. Hazard, D.L. Directions for Magnetic Measurements . Wash., D.C., G.P.O., 1921.

U.S. Coast & Geodet.Surv. Spec.Publ . no.166.

6. Hodgson, C.V., Manual of First-Order Triangulation . Wash., D.C., G.P.O., 1926.

Ibid . no.120.

7. Hoskinson, A.J., and Duerksen, J.A. Manual of Geodetic Astronomy. Determina–

tion of Longitude, Latitude, and Azimuth . Wash., D.C., G.P.O., 1947.

Ibid . no.237.

8. International Boundary Commission. Joint Report Upon the Survey and Demarca–

tion of the International Boundary Between the United States and Canada

Along the 141st Meridian from the Arctic Ocean to Mt. St. Elias .

Wash., D.C., 1918.

9. Leffingwell, E. de K. The Canning River Region, Northern Alaska . Wash., D.C.,

G.P.O., 1919. U.S.Geol.Surv. Prof.Pap . 109.

10. ✓ Madill, R.G. “The search for the North Magnetic Pole,” Arctic , vol.1,

T pp.8-18, Spring, 1948.

11. Mussetter, William, Manual of Reconnaissance for Triangulation . Wash., D.C.,

G.P.O., 1941. U.S.Coast & Geodetic Surv. Spec.Publ . no.225.

12. Rappleye, H.S. Manual of Geodetic Leveling . Wash., D.C., G.P.O., 1948.

Ibid . no.239.

13. Sverdrup. H.U. “Magnetic, atmospheric-electric, and auroral results, Maud

Expedition, 1918-24,” Carneg.Inst.Wash. Publ . no.175, vol.6, pp.309-524,

1927.

14. Swainson, O.W. Topographic Manual . Wash., D.C., G.P.O., 1928. U.S.Coast &

Geodetic Surv. Spec.Publ . no.144.

15. ✓ U.S.Coast and Geodetic Survey. Manual of Second and Third Order Tria gn ng ulation

and Traverse . Wash., D.C., G.P.O., 1929, Ibid . no.145.

16. ----. Manual of Tide Observations . Wash., D.C., G.P.O., 1935. Ibid . no.196.

       

Ralph W. Woodworth

Highways, Bridges and Protection from Ice Damage

EA-I. (Angelo F. Ghiglione)

HIGHWAYS, BRIDES, AND PROTECTION FROM ICE DAMAGE

       

CONTENTS

	Page
Location	1
Bridges	2
Road Construction	5
Maintenance	7
Effluent Seepage Icing	9
Stream and River Icing	11

Unpaginated      |      Vol_IIA-0310                                                                                                                  
EA-I. Ghiglione: Highways, Bridges, and Protection from Ice Damage

       

PHOTOGRAPHIC ILLUSTRATIONS

        With the manuscript of this article, the author submitted

16 photographs for possible use as illustrations. Because of the high

cost of reproducing these as halftones in the printed volume, only a

small proportion of the total number of photographs submitted by all

contributors to Volume I can be used, at most one or two of the illus–

trations accompanying each paper, and in some cases none. The selection

of halftone illustrations for Volume I must await further progress in

publishing plans, for the number that can be used will be determined by

the publisher, and the choice of those used should be made in conjunction

with a representative of the publisher. All photographs are, therefore,

being held at the Stefansson Library until a selection can be made.

001      |      Vol_IIA-0311                                                                                                                  
EA-I. (A. F. Ghiglione)

       

HIGHWAYS, BRIDGES, AND PROTECTION FROM ICE DAMAGE

        The accumulated experiences in Alaska of a generation of engineers,

construction men, and prospectors are properly reflected in the present

practices and operations of the Alaska Road Commission. The most workable

location, construction, and maintenance procedures for the near-arctic and

subarctic conditions encountered have been evolved through years of practice.

       

Location

        Most of the road planning in Alaska in pioneer location through virgin

country, which has not been surveyed or settled upon, and the route is,

therefore, not appreciably controlled by other than construction and sub–

sequent maintenance considerations. In addition to the usual location criteria

of conformance to the general road system planning, shortest route, standard

alig h nment and grades, reasonable economic design, and safety of traffic, ✓

certain very important regional requirements must be considered.

        Permanently frozen ground, or permafrost, underlies approximately

80 per cent of Alaska. Where at all possible, road location should avoid

these areas and the high construction and maintenance costs incident thereto.

The locating engineer soon learns to identify frozen ground by the type of

foliage and moss supported upon it.

002      |      Vol_IIA-0312                                                                                                                  
EA-I. Ghiglione: Highways, Bridges, and Protection from Ice Damage

        A prime consideration is the development of locations on the south,

rather than the north, slopes of hills and mountain ranges. Several reasons

for such southerly exposure of location, all directly resulting from the

appreciably greater heat effect of the sun, are as follows. First, the

f g round is more likely to be thawed and free from permafrost. Second, the ✓

construction will have the advantage of an earlier spring thaw and later

fall freeze-up together with more rapid thawing of the ground as it is

worked and exposed. Third, the maintenance problems are reduced [ ?]

by the lighter snows, less slippery surface, less winter ground ice forma–

tion, and earlier spring thaws.

        Wet sidehills or slopes, which indicate possible effluent seepages,

are avoided since spalling of slopes and major slides are to be expected

and winter ground icing will normally result. Likewise, the location must

be kept sufficiently above the known stream icing elevations of all streams

and rivers, either marginal to or crossing the line.

        Other precautions essential toward minimizing the winter maintenance

problems include avoiding through cuts which induce drifting, and planning

slightly raised or fill sections which tend to be swept clear of snow.

Normal construction where permafrost cannot be avoided is to use an unbalanced

fill. Minimum grades and curvature are utilized to reduce winter maintenance

and increase safety of winter traffic operation.

       

Bridges

        Bridge locations in subarctic areas require the additional consideration

of winter ground icing possibilities, stream ice break-up and flow, and the

channel-shifting to be expected of most glacier streams. In addition, numerous

003      |      Vol_IIA-0313                                                                                                                  
EA p -I. Ghiglione: Highways, Bridges, and Protection from Ice Damage

glacier rivers in Alaska are subject to extreme flash floods from the

bursting of glacier-dammed lakes or streams. Glacier floods in large rivers

such as the Nizina, Knik, and Kenai irregularly raise those rivers as much

as twenty feet and cause serious ice flow, bank erosion, and drift problems.

Such floods may occur in summer or in winter and, in the latter case, do

considerable damage by carrying heavy broken river ice against the bridges,

in addition to ice brought down from the glaciers, and ordinary drift com–

posed of trees, stumps, and other debris.

        The bridge locations, to cope with the above conditions, are preferably

chosen well in advance of the road location and act as control points for

the route. A narrow crossing where the river is confined in one channel

by geographical features is preferred and a high level crossing, supported

by geographical features, is similarly desirable. Such a location would

naturally eliminate many usually maintenance problems resultant from the

above-listed subarctic conditions. In actual practice, however, it is

usually necessary to accept less than the ideal crossing, since the economics

of the over-all route location seldom justify allowing the bridge crossing to

control the line.

        Bridge design must provide a minimum of restriction to river flow and

sufficient height to clear floods, ice flow, and winter ground and stream

icing formations. As a rule, clear spans are more satisfactory than trestle–

type structures, and mid-channel piers are undesirable since special icebreakers

and protective structures must nearly always be provided. On wide, flat,

glacier stream crossings where channel shifting is prevalent, the over-all

bridge length can often be reduced by utilization of dikes, wing dams, and

other channel control structures of restrict the flow to a single opening.

004      |      Vol_IIA-0314                                                                                                                  
EA-I. Ghiglione: Highways, Bridges, and Protection from Ice Damage

Such bank protective measure are costly and require continual maintenance,

but are often found economically justified by saving in cost, resulting

from decreased length of the bridge structure required.

        Standard steel bridges have been widely employed for Alaskan roads.

These bridges are mostly simple truss and girder spans, though arches, sus–

pension bridges, and cantilever designs are freely used for special crossings.

Timber T t restles and truss spans have been used extensively in the past but ✓

are being replaced with steel as rapidly as possible. The timber trestle is

used for small crossings and on secondary roads.

        Concrete is used for bridge seats, footings, and some abutments, but is

seldom used for spans or piers because of the comparatively high costs involved.

No cement is produced in Alaska and the freight costs to interior Alaska for

this bulky material amount to several times its value. Most gravel and sand

available for concrete aggregate requires extensive washing and screening to

remove glacial silt which predominates in the deposits. In the isolated

locations common to most Alaska bridge construction, these factors, together

with the additional plant and skilled tradesmen required for the aggregate

preparation, form erection, concrete mixing and placing, and heating during

cold weather placing, make concrete construction exceptionally costly. By

comparison, steel structures can be easily handled, freighted, and erected with

a relatively small plant setup. Steel structures in the North do not deterio–

rate appreciably as compared to similar structures in southern moist climates.

Concrete, on the other hand, deteriorates faster in the North due to the

numerous cycles of extreme freezing and thawing.

        Piers for the bridges in Alaska are predominantly of the steel “H”

piling bent type which have been developed by the Alaska Road Commission and

005      |      Vol_IIA-0315                                                                                                                  
EA-I. Ghiglione: Highways, Bridges, and Protection from Ice Damage

proved very satisfactory. Their cost is considerably less than comparable

concrete piers, the permanence is equal thereto, and the comparatively

simple handling and erection facilitates use in isolated locations. Their

cost is relatively low since they require none of the expensive excavation,

form work, cofferdam or caisson construction, or underwater work common to

concrete piers. In addition, they are well adapted to use in frozen ground

and can be placed as easily in winter as in summer. This factor is impor–

tant in Alaska where most bridge work is accomplished in the winter when

concrete operations require costly heating measures.

       

Road Construction

        The construction of roads in Alaska involves special problems and is

limited, in general, to the summer season by the frozen ground and the

extreme cold temperatures of the winters. This restriction results in

long periods of idle equipment, seasonal employment of crews, and increased

costs as mentioned above. Bridge work is usually scheduled for winter con–

struction. This is done in order to provide longer employment for key

personnel and to provide utilization of the otherwise idle equipment.

Other measure for reducing costs resulting from the limited seasonal con–

struction period include winter freighting of supplies and materials to

advanced construction sites while frozen rivers and swamps aid rather than

hinder such operations, winter camp erection, and concentration of equipment

overhaul in the winter months.

        Under normal conditions, the construction methods and equipment used

in Alaska are the same as those generally employed on large-scale road

construction projects in the United States. Discussion will, therefore,

006      |      Vol_IIA-0316                                                                                                                  
EA-I. Ghiglione: Highways, Bridges, and Protection from Ice Damage

be limited to the problems particular to the North where frozen ground is

one of the biggest obstacles to road construction. The swamp-covered

permafrost in Alaska is termed “tundra” and is generally a flat or rolling

terrain on which a thick moss insulates frozen ground beneath the surface.

The surface, however, thaws unevenly during each summer, and this produces

a continuous surplus of water. The moss and grass prevent adequate drainage

so that the water forms small pools and the frozen subsurface retards runoff

of this water, with the result that in the summer the ground is very swampy

and soft, even on relatively steep hillsides. The wet soil, practically

suspended in water, interferes with the operation of regular road-building

equipment, and the ice or frozen ground just beneath the wet cover impedes

grading operations.

        The best procedure in such cases is to avoid disturbing the equilibrium

maintained by nature between the factors in the permafrost province, known

as the thermal regime. Any construction operation which changes or disturbs

this thermal regime will be subjected to the forces of nature as they endeavor

to reestablish this equilibrium. Climatic conditions and geologic changes may

also affect the thermal regime and, thereby, result in either the degradation

of aggradation of the permafrost. Where at all possible, therefore, fill

sections are used over frozen ground — the fill placed with the least possible

disturbing of the moss or overburden. Where thawing has made the area swampy,

it is general practice to place a corduroy mat for additional protection and

support.

        Where the topography requires cutting into frozen ground, the work may

have to be programmed over several seasons to permit progressive thawing as

the exposed surface is worked off. Drilling the blasting of permafrost, as

007      |      Vol_IIA-0317                                                                                                                  
EA-I. Ghiglione: Highways, Bridges, and Protection from Ice Damage

in the case of rock, is resorted to in some cases in order to accelerate

breakdown of the impermeable material.

       

Maintenance

        Summer maintenance of roads in the northern regions of Alaska requires

very much the same procedures as used in the Midwestern States. After the

spring thaw the roads dry out and become dusty, even though frozen ground

may be only a few feet below the grade. Particular local problems of

heaving, sliding, or subsiding ground, resulting from the uneven thawing

of the underlying frozen ground, require continual maintenance attention

and are quite common. Corrective measures include removal of slide material

or placing of additional surfacing material to reestablish uniform vertical

alig h n ment. ✓

        Brush cutting, ditch and culvert cleaning, spot graveling, and other

usual maintenance requirements are of necessity concentrated in the summer

working season. In addition, all possible preliminary steps toward facili–

tating winter maintenance are taken. Such measures include placing culvert

stakes and snow takes of sufficient height to be discernible above snowdrifts

to aid in locating the culverts and the edge of the road when thawing or

plowing; placing of snow fences and ice fences where know drifting or

icing occurs; flattening of the road crown in the fall to minimize danger

of sliding on icy roads; and building up stockpiles of sand and cinders

for winter surface sanding.

        In the consideration of winter road maintenance, and Alaska Road

Commission has of necessity developed methods of preventing and coping with

winter ground ice formations that endanger highways and highway structures,

008      |      Vol_IIA-0318                                                                                                                  
EA-I. Ghiglione: Highways, Bridges, and Protection from Ice Damage

and constitute a serious hazard to normal traffic flow. Such ice forma–

tions are locally known and described throughout Alaska as “glaciers”

and any other designation would be confusing to the average maintenance

man. However, the term is incorrectly applied and since true glacial

conditions are seldom encountered on road maintenance, the term will be

used only when correctly applicable to masses of snow-formed ice. In this

article, winter ground ice formations particularly affecting winter highway

travel will be referred to as “icing.” Icing results from the successive

freezing of sheets of overflowing water into masses of ice attached to the

ground. For road maintenance considerations, these ice formations are

classified into two general types — the effluent seepage type and the river

or stream type. Ground icing of the effluent seepage type is experienced

throughout most of Alaska while the river or stream type is prevalent only

in the interior as differentiated from southeast and south-central Alaska.

        As would be expected, the actual formation of the ice masses varies

unpredictably with the ground, water, and weather conditions. The severity

of the winter, the amount of snowfall and whether it falls early in the

season or late, and the nature of the season prior to the freeze-up, whether

wet or dry, all comprise contributing factors toward the resultant icing

possibilities. From past experience, certain generalities as to these

factors have been deduced and may be briefly summarized as follows:

        ( a ) A rainy season prior to freeze-up will increase the ground-water

flow in winter and usually cause more and heavier icing.

        ( b ) An early heavy snow will tend to insulate the ground and minimize ice

formation. Conversely, prolonged freezing weather with little snow results

in considerable icing.

009      |      Vol_IIA-0319                                                                                                                  
EA-I. Ghiglione: Highways, Bridges, and Protection from Ice Damage

        (c) A severe winter with long periods of extreme cold may tend to

freeze back and stop the flow and formation of seepage-type ice but will

increase the formation of the stream and river type. The reverse is

generally true of mild winters.

        These generalities cannot be considered infallible since various com–

binations of the conditions may produce opposite results. As a result,

methods of controlling the ice have been developed both as preventative,

where possible to forecast probable formations, and as control measures

where the ice forms infrequently or unpredictably.

       

Effluent Seepage Icing

        The effluent ground seepage ice is the predominant form to be coped

with in winter maintenance operations in Alaska. When relatively warm

ground seepage meets the surface of a highway-cut slope in summer, it

normally may evaporate, flow down the slope and into the regular drainage

ditches, or may continue to flow just under the surface. However, in the

winter, with continued freezing temperatures, this flow freezes soon after

exposure to the air and forms successive l ev ay ers of ice which build up to ✓

many feet in thickness or until hydrostatic equilibrium is reached. Since

this type of ice normally forms on sidehill cuts, the resultant sloping ice

surface built into the road increases the danger to traffic by crowding it

to the outer edge and tilting it toward the outside at increasingly steeper

slopes. This type of icing, besides building to many feet in depth, often

forms slopes too steep to permit passage of any kind of traffic.

        A relatively inexpensive and very workable method of controlling this

type of icing has been developed by the Alaska Road Commission and has proved

010      |      Vol_IIA-0320                                                                                                                  
EA-I. Ghiglione: Highways, Bridges, and Protection from Ice Damage

so successful that its use has spread throughout the Territory and into

Canada where similar problems occur. Termed “ice fencing,” this method

employs the principle of damming of the seepage and controlling its freezing

before it reaches the road. Since the actual head of water to be diverted

is never more than the depth of the seepage film, the term “dam” is mis–

leading and the actual fence used may be of light temporary construction.

        In operation, the ice fence is placed as soon as icing is observed, or,

in cases of annually repeating ice, may be placed before the freeze-up.

The fence consists of wire netting on pos e t s to which has been fastened to ✓

a layer of canvas, roofing paper, or similar relatively impervious material.

The posts may be buried in the ground, if placed prior to the freeze-up,

may be frozen in holes picked into already formed ice, or may be temporary

tripods. The wire netting used is either fish-trap wire, chicken wire, or,

in some instances, standard slat-type snow fencing. The resultant fence,

with impervious facing for diverting the seepage, need only be of sufficient

strength to withstand the local winds. It will actually be increasingly

stabilized by the ice as the thickness of the controlled icing develops.

        The ice fence is placed between the seepage and the road and actually

controls the ice by diverting the flow parallel to the road until it freezes.

The resultant vertical wall of ice may build up to considerable depth and

require a second and sometimes a third lift of the fence during the winter.

These fences may have proved very effective in keeping ice from forming on

the roads and are especially preferred to other control methods since only

infrequent attention of the maintenance crews is required.

        While the ice fence has simplified control of forming ice, it is still

possible, in some instances, to avoid the icing problem entirely by striking

011      |      Vol_IIA-0321                                                                                                                  
EA-I. Ghiglione: Highways, Bridges, and Protection from Ice Damage

closer to the source. Interception ditches, graded to pick up the seepage

before it reaches the road out and to divert it into other drainage channels,

are possible. This type of control can be used effectively where the ground

water flows near the surface and can be intercepted at some distance from

the road.

        Similar interception ditches to collect and channel the seepage flow

have been effective where such concentrating of the water preserves suffi–

cient latent heat to keep it from freezing until the water has passed through

the road drainage structures. While icing will probably still occur, it will

be below the road and of no danger to traffic. An added measure to insure

operation of this type of diversion consists of covering or insulating the

channeled flow against rapid freezing in order further to delay the icing.

A practical method consists of covering the ditch with brush of sufficient

thickness to support snow; the snow cover provides considerable insulation.

        Where flow of ground water can be intercepted at some distance from the

road, it is also possible to cause or control the icing by exposing the

seepage at a desired location. Clearing and stripping or simply ditching

may provide sufficient interception and exposure to initiate the icing where

desired.

       

Stream and River Icing

        An ice problem more easily coped with is that of stream or river icing —

formed when the stream freezes to its bed and then continually overflows

and freezes, forming successive ice layers, in many cases reaching depths

of more than 20 feet. This type of icing occurs where the stream flows

over permafrost, and is relatively predictable, since it occurs year after

year in the same locations. The bridges planned for crossing such streams

012      |      Vol_IIA-0322                                                                                                                  
EA-I. Ghiglione: Highways, Bridges, and Protection from Ice Damage

must be kept sufficiently high to prevent the overflows from reaching the

level of the deck with the resultant heavy ice loads built onto the

structure and danger to traffic. Where overflow has occurred, the bridge

is not structurally endangered until the period of spring thawing when

the stream cuts back down to its bed and undermines the ice, leaving many

tons of it hanging on the bridge. In such cases, it is often necessary to

remove large quantities of ice from the structure by chopping, thawing and

cautious use of blasting charges.

        Besides planning high level bridges for icing stream crossings, it is

important that a clean understructure or clear span be used. As mentioned

above, use of trestle-type structures is avoided, if possible, since the

removal of the ice formations from the trestle supports is extremely diffi–

cult to accomplish without damaging the bracing.

        Where an icing stream threatens to close the o ep pe ning of a large culvert ✓

or a bridge, the stream may sometimes be kept flowing through the opening by

channeling and heating. The application of heat to the water above the

opening tends to delay its freezing until below the highway and also to cut

out a channel in the already formed ice. The heat may be supplied either by

means of a boiler through steam pipes laid above or through the opening, or

more simply by means of a 50-gallon steel drum heater placed on end in the

channel above the opening. This type of heater is merely a drum with one

end cut out and in which a fire is maintained by use of oil or wood. Usually

an infrequent fire, once a day or less, will provide sufficient heat to keep

the channel open.

        Where icing streams and rivers parallel highways, the principal protec–

tive measure is again that of building the road sufficiently high to avoid

013      |      Vol_IIA-0323                                                                                                                  
EA-I. Ghiglione: Highways, Bridges, and Protection from Ice Damage

overflow. Where overflow of the road does occur, continual attention is

necessary to maintain traffic and to protect the road from subsequent

washouts during the spring thaw and runoff period. During winter mainte–

nance of such sections of road, it is necessary to provide a relatively

flat and level traveling surface for the safe operation of traffic by

picking wheel ruts, diver g t ing or chan n eling the overflow, and blasting and ✓ ✓

blading the uneven ice. Numerous instances of traffic being maintained

over long sections of the ice several feet thick without the public being

aware of its being completely off the road surface have been the result of

proper maintenance provisions.

        During the spring thaw and runoff, it is essential that culverts be

thawed open and the streams be controlled in their regular channels as

quickly as possible. Culvert thawing is usually accomplished by means of

steam from small truck-mounted boilers. Varying lengths of small-sized

pipe (usually ½' in.) are connected with sufficient steam hose to permit

working at considerable distance from the boiler position on the road. The

pipe is worked through the ice in the culvert as the steam thaws ahead —

usually starting from the lower or outlet end in order that the melted water

may escape. It is essential that culvert stakes be set prior to winter

maintenance in order to facilitate locating frozen culverts for thawing.

All culverts are staked by the Alaska Road Commission in a uniform manner

to simplify these operations.

        In some instances the thawing of culverts by the method described above

is impracticable. Such cases are encountered in extremely long culverts as

under high fills, in culverts which have had several feet of ice form around

and above the inlet and, in some instances, also above the outlet, and in

014      |      Vol_IIA-0324                                                                                                                  
EA-I. Ghiglione: Highways, Bridges, and Protection from Ice Damage

old partially collapsed or deformed culverts through which a straight

thawing pipe is difficult to handle. Where the failure of such a culvert

might endanger a large fill or critical section of road, thawing may be

provided by means of permanently installed thawing pipes. Such pipes of

relatively small diameter are hung inside the culvert prior to the freeze-up,

carried out and up to easily accessible locations on each end, and capped

to prevent plugging by condensation. Any necessary thawing of the culvert

may subsequently be accomplished by attaching a line from a mobile steam

boiler to the permanently installed pipes.

        In large fills where the culverts are extremely long, an added precaution

is sometimes taken by installing a “relief” culvert near the top of the fill

above the icing height. Such relief culvert will handle spring runoff until

the lower culvert thaws open.

        The freezing back of thawed culverts during spring operations may be

partially controlled by use of rock salt — a quantity of salt deposited near

the culvert inlet in a burlap sack will tend to prevent such freezing until

the flow of the thawing runoff cuts a sufficiently large opening through

the ice.

        Where roads are not kept open during the winter and icing has been

allowed to proceed uncontrolled, a considerable problem for traffic results

in the spring opening. In extrems cases, such ice has covered sections of

road several thousand feet in length and to depths exceeding 20 feet. Re–

moval requires blasting, cutting with tractor and bulldozer, and repeated

blading as the surface softens through thawing. Sprinkling dirt or ashes to

accelerate the thawing effect of the sun is effective, and also liberal use

015      |      Vol_IIA-0325                                                                                                                  
EA-I. Ghiglione: Highways, Bridges, and Protection from Ice Damage

of rock salt will expedite the ice removal. While traffic can be main–

tained over relatively flat thawing ice, it is sometimes hazardous and

requires the constant attention of the maintenance forces.

        Numerous other ice problems are encountered in road work in Alaska,

but are of relatively minor importance and will, therefore, be dealt with

briefly.

        Ice flow in rivers during the break-up period, known as debacle, con–

stitutes considerable menace to bridge piers and marginal road structures

and fills. Protective measures include ice shears, heavy rock riprap, and

steel piling icebreakers on the upstream sides of the piers. Timber piling,

as in trestle structures, must be sheeted with metal or planked for full

width of bend above and below ice line to prevent being cut off by passing

ice.

        Frost mounding and frost heaving, while deforming the roads in places,

do not usually constitute serious hazards to winter traffic. Frost mounds

have, in instances, upwarped the surface as much as six feet in the middle

of the road and have again subsided leaving no apparent damage. The opposite

action occurs occasionally where roads are located over permafrost containing

ice lenses or ice veins. The uneven melting of the ice or the shifting of

underground water channels may cause serious subsidence of many feet over

relatively short periods of time.

        Frost boils, resulting from uneven and accelerated spring thawing, are

a serious problem to proper road maintenance and result in rough and some–

times impassable roads. Maintenance procedures include covering with coarse

pervious gravel, removing the weakened surface material by digging or blasting

with ditching powder and backfilling with coarse gravel, or by - passing the ✓

016      |      Vol_IIA-0326                                                                                                                  
EA-I. Ghiglione: Highways, Bridges, and Protection from Ice Damage

traffic and permitting the boil to dry up naturally where road width will

permit.

        With the every-increasing winter traffic flow over the principal

Alaskan highways, the problems incident to proper and safe maintenance

operations are becoming of greater importance in the over-all highway

program. Additional preventive measures are justified both in the initial

construction planning and in the maintenance improvements such as minor

changes in alignment and grade. As an accumulated result, the actual daily

winter maintenance problems are being simplified, the general winter travel

conditions are being steadily improved, and the highways are being made

safer for use by the general public.

       

Angelo F. Ghiglione

Drainage, Flood Control and Beach Erosion in Alaska

EA-I. (James Truitt)

DRAINAGE, FLOOD CONTROL, AND BEACH EROSION IN ALASKA

       

CONTENTS

	Page
Lowell Creek	3
Tanana River and Chena Slough	5
Salmon River	7
Skagway River	8
Erosion	10

001      |      Vol_IIA-0328                                                                                                                  
EA-I. ( Colonel James Truitt)

       

DRAINAGE, FLOOD CONTROL, AND BEACH EROSION IN ALASKA

        Degradation of the land mass throughout Alaska is progressing at a

relatively high rate as the result of water action, despite the fact that

the major drainage systems are icebound and practically dormant for fully

50 per cent of the year. In general, the central portion of Alaska is not

subject to heavy precipitation or torrential rainfall normally associated

with serious flood conditions. Flooding along Alaskan water courses does

not conform to the general concept of disastrous floods in that the duration

and extent of inundation are quite limited. However, the steep gradients

and resultant velocities of the uncontrolled waters cause serious destruction

in their path and threaten the establishment of channel changes. Consequently,

stream bank erosion and flooding are matters of primary concern in the planning

of all large-scale developments in Alaska.

        The principal Alaskan streams have their sources in the snow and ice

fields of the surrounding mountains, hence, floods of various magnitudes may

be expected during the warmest and driest period of midsummer. The intensity

of this type of flood may vary from a bank-full stage, resulting from an uninter–

rupted discharge of snow-melt, to out-of-banks flash floods caused by the forma–

tion of local ice jams or the failure of ice dams at or near the terminus of

hanging glaciers. Two outstanding examples of such flooding characteristics

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EA-I. Truitt: Drainage, Flood Control, and Beach Erosion

are noted in the Knik River, discharging into the head of Knik Arm, Cook

Inlet, and the Copper River which empties into the Gulf of Alaska. Devas–

tating flash floods are practically annual occurrences on these streams

and are responsible for serious damage to bridges and other improvements

in their lower reaches. In 1926, the writer was directed to investigate

the source of these damaging floods in the Copper River drainage and to

determine what, if any, steps could be taken to prevent their reoccurrence.

The source was found to be at the foot of the Skolai Glacier in the head–

waters of the Nizina River, a tributary of the Copper. In this case, an

arm of the glacier abuts a vertical rock wall, forming a dam which impounds

a lake some 5,000 acres in extent. By midsummer, the snow- and ice-melt

from the glacier fills this basin and when the hydrostatic pressure reaches

about 120 feet, the gravel base under the ice dam blows out releasing the

entire lake down a channel where the gradient varies from 7 per cent

initially to about 2 per cent in the lower reaches. The top o graphy at the ✓

abutment of the ice dam is such that a spillway and short tunnel through

the rock wall could be built to relieve this condition. However, such a

plan could not be recommended since the tunnel would in all probability

become inoperative because of ice. Furthermore, the high cost of construc–

tion in this extremely remote locality would have far outweighed the benefits

that would then accrue. A somewhat similar condition exists at the head of

the Knik River and there are undoubtedly many other instances that have not

been investigated or reported.

        Floods in the Salmon and Skagway rivers, in the coastal regions of

southeastern Alaska, follow a much more conventional pattern, as floods in

these drainages generally occur in the early spring following heavy rains

003      |      Vol_IIA-0330                                                                                                                  
EA-I. Truitt: Drain ing age , Flo o d Control, and Beach Erosion

and the accelerated melting of the snow cover in their basins.

        A combination of flood causes exists in the case of Lowell Creek a

mountain torrent which discharges into Resurrection Bay at Seward. Floods

in this stream are unpredictable. It may flood in the early spring due to

unusually heavy precipitation, or at any time in midsummer by the release

of glacial impoundments at its source.

        The Tanana River, in central Alaska, is subject to flooding and dis–

tributary channeling in the Tanana lowlands above Fairbanks as the result

of ice jams during the spring break-up. The condition in the Fairbanks

area is further aggravated by the general movement of the Tanana River

toward the right limit of its valley floor, due to the fact that the tribu–

taries from the Alaska Range which form the left limit of the valley have

extremely steep gradients, and, in consequence, are building up the valley

floor with heavy detritus, thus forcing the river toward its northern limit.

        Each waterway presents its own characteristic flood pattern. The limited

development in Alaska to date has only warranted the investigation or the

a e d option of control measures on a few streams. A brief description of the ✓

flood-control projects which the Corps of Engineers has been called upon to

provide in Alaska follows.

        Lowell Creek. This is a Lowell Creek small stream discharging into

the head of Resurrection Bay at Seward, Alaska. It drains a 5-square mile

of glacier-covered mountain slopes through a deeply incise s d channel. Owing ✓

to its extremely steep gradient, it transports immense quantities of glacial

detritus at flood stage. During ages past, this material has been deposited

immediately upon release of the stream from the confines of the canyon section

to form a delta, which now extends seaward from the mountain wall for a distance

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EA-I. Truitt: Drain [ ?] age , Flood Control, and Beach Erosion

of about 1,200 yards on a slope of 5 per cent. This delta became the

townsite of Seward, Alaska, and later the southern terminus of the govern–

ment-owned Alaska Railroad.

        A series of unusually severe floods during the years 1923 to 1926,

inclusive, caused extended interruption of traffic on the Alaska Railroad,

with consequent effect on settlements throughout the Alaska Railroad belt.

        The need for control measures on this waterway was apparent, and under

authority of an Act approved February 9, 1927, the Alaska Road Commission

constructed a rectangular timber flume, 12 feet wide, 7 feet deep, and

3,300 feet in length, to convey the debris-laden flood waters from the

mouth of the canyon across the townsite to tidewater. This improvement

was completed in 1929 and served adequately until 1935, by which time the

deposit of solid materials at the outlet of the flume had built up to such

an extent that free discharge was no longer possible and the flume became

choked with boulders and gravel during every flood stage. The volume of

solids transported is indicated by the effect of a flood in October 1935,

when the flume was completely filled with gravel from outfall to intake, a

total quantity of 10,000 cubic yards in 11 hours. The actual quantity of

solids transported considerably exceeded this apparent amount since the

flume functioned to a limited degree for the initial 3 hours of this 11-hour

period.

        A revised plan of control was necessary and further studies were made

by the Corps of Engineers. As a result of this investigation, it was

decided that the only plan that would insure full protection to the town

of Seward and the terminal facilities of the Alaska Railroad would require

005      |      Vol_IIA-0332                                                                                                                  
EA-I. Truitt: Drainage, Flood Control, and Beach Erosion

a complete diversion of Lowell Creek from the townsite area. This condi–

tion could be met most satisfactorily by construction of a low dam across

the canyon, about 1,500 feet above its mouth, and a discharge tunnel

2,100 feet in length, through the mountain forming the right limit of the

canyon. This plan would permit discharge of the flood waters at an ele–

vation 65 feet above sea level and about 1,000 feet away from any developed

area, thus providing a disposal site for about seven million cubic yards,

or a usable life of about 180 years.

        The project was adopted by the Congress in August 1937, completed by

the Corps of Engineers in 1940, and provides necessary flood protection

to the community and the terminal facilities of the Alaska Railroad.

        Tanana River and Chena Slough. The Tanana River has its source on the

northern slopes of the Wrangell Mountains near the Alaskan-Canadian border,

flows northwesterly about 500 miles, and discharges into the Yukon River,

140 miles west of Fairbanks. The river closely follows the northern limit

of the Tanana lowlands, its valley floor, where it has been forced by the

deposition of heavy glacial debris brought down by tributaries from the

north slopes of the Alaska Range which form the left limit of the valley.

The Chena River, a southwesterly flowing tributary of the Tanana, has its

source on the low divide between the Tanana and Yukon rivers and flows

through rolling hill country to emerge onto the valley floor of the Tanana

about 20 miles above its actual confluence with the Tanana River.

        The city of Fairbanks and the military reservation that embraces Ladd

Field are located in the lowland area between the Tanana and Chena rivers,

about 10 miles above their confluence. The Tanana River lowland in this

locality are subject to overflow during the spring break-up, and the security

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EA-I. Truitt: Drainage, Flood Control, and Beach Erosion

of Fairbanks and other improvements in the vicinity were further threatened

by the existence of Chena Slough, a distributary of the Tanana, which drains

from the Tanana at high water stage and flows westerly to join the Chena

River a few miles above Fairbanks.

        A marked increase in the volume of water carried by Chena Slough with

each succeeding flood stage in the Tanana River indicated that a flow far

exceeding the capacity of the Chena River channel at Fairbanks could be

expected, and there was considerable evidence pointin t g to an eventual ✓

channel change of the entire Tanana River.

        Pursuant to Act of Congress, June 1936, the Corps of Engineers was

directed to investigate the condition and determine what action might be

taken to avert disastrous floods in the Fairbanks area. The investigation

revealed that the outflow from the Tanana River into the Chena Slough

channel was through a number of small chutes in a reach between 25 and 30

river miles above the mouth of the Chena River, and that ice james in the

Tanana were responsible for enlargement of existing overflow channels as

well as the creation of new distributaries in this area. The unstable

condition of the river banks and the length of the reach involved precluded

consideration of bank stabilization; hence, less conventional methods of

control were necessary. Field surveys developed that the Chena Slough

drainage was concentrated against a rock point projecting into the valley

floor from the north limit at a point about 15 miles east of Fairbanks.

The Corps of Engineers recommended that a rock-fill dam be constructed across

Chena Slough at this point and the barrier extended southwesterly as a

training dike across the valley floor for about 16,000 feet to the right

bank of the Tanana River, thus collecting and returning all overflows to

the main river.

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EA-I. Truitt: Drainage, Flood Control, and Beach Erosion

        The plan was adopted and authorized by Congress in 1938. The project

was completed in 1941 and has provided full protection against flood menace

from this source. It should be noted, however, that there is no assurance

against further attacks of the Tanana River along its right limit down–

stream from the improvement provided.

        Salmon River . Salmon River has its source in the precipitous mountains

of the coastal range in southeastern Alaska and empties into the head of

Portland Canal at Hyder on the extreme southeastern border of Alaska. It

flows through a deeply incised valley generally less than one-half mile

in width and its total length is about 25 miles. It is fed by numerous

mountain torrents heading 3,000 to 5,000 feet above sea level in the snow

fields of the mountain slopes. The gradient of Salmon River is extremely

steep in its upper reaches and it retains a fall of 30 feet in the final

mile above tidewater; hence, velocities are capable of developing new

channels at any flood stage through the unconsolidated materials on which

the town and port facilities of Hyder are located. Hyder had been frequently

inundated, and destruction of the town and its port facilities were threatened

by the encroachment of Salmon River.

        Rapid shoaling at the head of Portland Canal was seriously restricting

navigation at the head of this waterway. The port of Stewart, British Columbia,

just across the boundary line, was already deprived of navigable depths and

a recent change in the trend of the Salmon River at its mouth indicated the

delta would shortly include the wharf area at Hyder. Corrective measures

were necessary both in the interests of navigation and the control of floods.

        In January 1931, Congress directed an investigation with a view toward

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EA-I. Truitt: Drainage, Flood Control, and Beach Erosion

the control of floods. The corrective measures recommended consisted of

a stone-faced wing dike, 4,400 feet in length, extending from a rock point

on the left limit of the river above the townsite to a point on the fan

where the greater slope was toward the right limit of the delta. This

plan afforded flood protection to the townsite of Hyder and the wharf

approaches, and also diverted the discharge of debris away from the wharf

face toward deeper water in the Portland Canal.

        The project was authorized by Congress in 1934, and constructed by

the Corps of Engineers in 1935. It has afforded the protection desired

and maintenance costs have been negligible.

        Skagway River. This water course has its source in White Pass, a

relatively low saddle in the coastal range between northwestern British

Columbia and tidewater at Skagway. Its steep, narrow valley provided an

access route into the Klondike during gold-rush days and was later developed

for the location of the White Pass and Yukon Railway, a narrow gage line,

110 miles in length, connecting Whitehorse, Yukon Territory, with the

United States seaport of Skagway.

        The total length of the river is less than 15 miles and it drains an

area of approximately 125 square miles of mountainous terrain. It discharges

into the head of Taiya Inlet, and in recent geological time, it has brought

down sufficient rock waste from the surrounding mountains to fill the head

of the inlet for a distance of about 3 miles. This deposit of unconsolidated

material became the site of Skagway but the building process is still in

progress; hence, the security of all developments in the lower reach of the

river was threatened at every flood stage.

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EA-I. Truitt: Drainage, Flood Control, and Beach Erosion

        Investigation of the condition with a view toward providing flood

protection for the Skagway townsite and wharf area was directed by Congress

in 1935. In response thereto, the Corps of Engineers recommended the con–

struction of a rock-faced levee along the left limit of the stream, extend–

ing 6,700 feet downstream from a stable abutment on the canyon wall through

the townsite area to tidewater, with an 1,800-foot rubble mound breakwater

extension over the tide flats to deflect the river discharge away from the

wharves.

        The project was authorised by Congress in 1938 and completed in 1939.

Further improvements in the interests of navigation by extension of the

breakwater was subsequently authorized.

        The growing recognition of the strategic and economic importance of

the Territory of Alaska will undoubtedly result in its rapid development.

Stream valleys will certainly be adopted as the site of future communities

and the information that has now been collected and recorded on the flooding

characteristics of Alaskan streams can be of inestimable value in the planning ✓

for permanence and security.

        The control of floods will, of course, become a matter of greater concern

as settlement and development of the Territory increases. However, it is felt

that future developments will be planned, taking into consideration the flood

characteristics of adjacent waterways. These conditions were not recognized

or carefully weighed in the siting of early settlements in Alaska, as

evidence s d at Seward townsite, laid out on the built-up delta of Lowell Creek, ✓

where it emerges from the canyon section, and again, in the case of all Tanana

lowland developments along the right limit of the Tanana River, where continual

encroachment of the river is indicated.

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EA-I. Truitt: Drainage, Flood Control, and Beach Erosion

        Erosion of the coast line of Alaska is relatively nonexistent. Although

some beach erosion has occurred at Nome on the Seward Penninsula as the

result of severe storms, the coast line generally is building up rapidly

from the discharge of silt-laden rivers and streams. This condition is

readily noted throughout the entire coast line from the head of Portland

Canal in southeastern Alaska to the mouth of the Colville River, discharging

into the Arctic Sea.

        The delta of the Stikine River in southeastern Alaska has practically

annexed an offshore island to the mainland within the recorded history of

Alaskan shipping. Shoaling of the tidal waterways at the head of Knik Arm

has progressed so rapidly that small trading schooners that served trading

posts in this region as late as 1910 can no longer navigate these waters.

The extensive de l ta l s of the Kuskokwim and Yukon rivers can be readily noted ✓

from any map of Alaska, but the deposition of the silt load of these streams

is not confined to the delta areas, as indicated by the existence of extensive offshore ✓

bars reaching for many miles from the river mouths in the direction of the

littoral drift.

       

James Truitt

Strength and Uses of Fresh and Salt Water Ice

Unpaginated      |      Vol_IIA-0338                                                                                                                  
EA-I. (Ralph Hansen and Kenneth Linell)

STRENGTH AND USES OF FRESH AND SALT WATER ICE

       

CONTENTS

	Page
Uses of Ice in the Arctic	1
Strength Properties of Ice	3
General Characteristics of Ice	3
Published Test Results	4
Effect of Intracrystal Structure of Ice	4
Effect of Impurities in Ice	5
Effects of Horizontal Stratification in Ice	7
Effect of Vertical Cracks	8
Temperature during Ice Formation	8
Residual Stresses	9
Effect of Temperature during Test	9
Effect of Rate of Loading on Strength Tests	12
Effect of Orientation of Test Specimen	13
Size and Proportion of Test Specimens	13
Load-Bearing Capacity of Ice	14
Records of Actual Ice Loadings	14
Historical Military Rules	14
Moskatov’s Empirical Method	15
Elastic Theory Analysis	16
Preliminary Elastic Theory Ice Thickness Curves	23
Comments on Elastic Theory Method and Thickness Curves	23
Effects of Moving Loads	25
Methods of Increasing Supporting Capacity of Ice	26
Bibliography	28

Unpaginated      |      Vol_IIA-0339                                                                                                                  
EA-I. Hansen-Linell: Fresh & Salt Water Ice

       

LIST OF FIGURES

		Page
Fig. 1	Bearing capacity of old sea ice for airplanes with wheels	16-a
Fig. 2	Bearing capacity of fresh-water ice for airplanes with wheels	16-b

001      |      Vol_IIA-0340                                                                                                                  

       

STRENGTH AND USES OF FRESH AND SALT WATER ICE

       

Uses of Ice in the Arctic

        The most important use of both sea ice and fresh-water ice in the Arctic, —

in the present and in the past, has been in aid of transportation. The most

famous journeys of such explorers as Peary, MacMillan, and others were made

over frozen seas, on foot or with sledge and dog team. In many arctic areas

frozen rivers, lakes, and bays are regularly used for winter travel between

land points, frequently shortening distances by many times over those required

for overland travel. Ice makes possible the passage in winter of tractor–

drawn supply trains over water bodies, swamps, and bogs which in other times

of the year would be impassable.

        Even railroads have been constructed on floating ice. The Russians have

been particularly persistent in developing this type of construction. A rail–

road line was, for example, constructed on the ice of Lake Ladoga in the siege

of Leningrad in World War II, supplementing motor truck supply routes also

laid out over ice. The value of ice in assisting military operations by pro–

viding relatively easy means of crossing rivers, lakes, swamps, and other water

areas is obviously very large in arctic areas.

002      |      Vol_IIA-0341                                                                                                                  
EA-I. Hansen-Linell: Fresh & Salt Water Ice

        The ice of the Arctic provides a surface to support floating weather

and scientific stations, a notable example of which was the Soviet Papanin

Expedition, which was established on the ice at the North Pole in May 1937,

and for nearly a year gradually drifted southward, until removed from the

ice at a point off the coast of East Greenland in February 1938.

        Various possibilities for increasing the structural usefulness of ice

remain to be explored. A start was made in this direction during World War

II in an investigation carried out under the direction of Dr. C. J. Mackenzie,

President of the National Research Council of Canada (4). The object was to

devise a means of constructing floating airdromes of ice, which would save

critical materials required in other methods of creating landing facilities.

The successful prosecution of the war in Europe resulted in abandonment of

the project, but not before it had been found that by means of an admixture

of about 14% wood pulp, the compressive strength of ice could be increased to

1,100 p.s.i. and its tensile strength to 700 p.s.i. Other means for using ice

for various structural purposes have been suggested but have received little

or no actual trial.

        Ice serves as a water supply source in the Arctic. In land areas, all

surface water sources will usually be completely frozen in the winter and the

only available source of water will be from the melting of ice or snow. In

salt-water areas, fresh water is obtainable by melting old sea ice; in summer, —

melting of this ice forms pools of fresh water on the surface of the ice.

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EA-I. Hansen-Linell: Fresh & Salt Water Ice

       

Strength Properties of Ice

        General Characteristics of Ice . Ice may be described as a highly viscous

material having characteristics of a solid. Various observers have reported

that the range of stress magnitudes within which ice is truly elastic is quite

small. Although it fractures like a brittle material under breaking loads,

ice will flow or deform gradually under nonfailure loads, the rate of deforma–

tion under a given stress being higher at higher temperatures. Under favorable

conditions for “creep,” deformation may be quite rapid. Ice will also melt

under pressure; the effect is most pronounced with ice temperature at 32° F.

The pressure required to cause melting increases very rapidly with only small

drop in temperature below 32° F.

        It will be apparent from these ice characteristics that it is not easy

to express the action of ice under stress by one or two simple figures. For

a material such as steel, working stresses may very easily and accurately be

established in relation to its yield point. For ice the yield point is some–

what obscure, and is apparently below practical working stresses; as yet, the

only really useful orientation point on the stress-strain curve is the failure

point. When a steel structure is designed, material of given characteristics

is specified with assurance that the actual steel used will vary an insigni–

ficant amount from the assumed properties. With ice, however, the material which

Nature has formed must be used, and its strength will vary considerably, in

accordance with the chance variations of the several strength-influencing factors

involved. Even cakes of artificial ice manufactured apparently identically

show wide spreads of results.

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EA-I. Hansen-Linell: Fresh & Salt Water Ice

        Published Test Results . Ranges of some ice-strength results are shown in

Table I. These results represent tests under a wide variety of test methods

and conditions on many types of ice (including artificial ice) and on speci–

mens of a wide range of shapes and sizes. Most of the figures are individual

maximum or minimum test values reported by the various investigators (1; 3;

5; 7; and original data). Except for strengths of single crystals, the minimum

Table I. Ranges of Ice Strength Test Results . ✓

Type test	Values reported, p.s.i.
Compressive strength	70-1,800
Tensile strength	36-223
Flexural strength	44-311
Shear strength	39-353

        values should actually approach zero, corresponding to the condition when ice

is rotting or candled and is able to support virtually no load. Possibly the

compressive strength values show the greatest range, in part because more

investigators have used this relatively easy test than the other types.

        Effect of Intracrystal Structure of Ice . When an ice sheet is formed on

the surface of a body of fresh water, the ice crystals form with their optic

axes vertical; that is, with their basal planes horizontal, and grow downward

with the added ice having its basal planes also [ ?] parallel with the ice surface.

This influences the over-all strength since, as reported by McConnel from his

study of the way ice yields to stresses, the individual crystal behaves as if

it consists of an infinite number of indefinitely thin sheets of paper, normal

005      |      Vol_IIA-0344                                                                                                                  
EA-I. Hansen-Linell: Fresh & Walt Water Ice.

to the optic axis, fastened together with [ ?] some viscous substance which allows

one to slid e over the next with great difficulty. The sheets “offer no resistance ✓

to bending, but utterly refuse to stretch except, of course, elastically” (9).

Thus, on the basis of the structure within the individual ice crystals themselves,

and apart from other structural characteristics, the properties of ice determined

from tests may be expected to vary according to the direction of orientation of

the applied stresses between the horizontal and vertical, relative to the

original surface of naturally formed ice.

        Effect of Impurities in Ice . The presence of relatively small amounts of

dissolved or suspended matter in water usually results in ice that is weaker

and/or which deteriorates more readily under the effects of warmer temperatures

and sunlight. However, additions of considerable amounts , of such materials ✓

as wood pulp, as noted previously, are reported capable of increasing strength,

and also may serve to slow up the melting (4).

        In any water body found in nature, there will be found some dissolved

minerals and other impurities. Sea water at one extreme is an obvious

example, but even the clearest natural fresh-water body is not without impurities. ✓

When each ice crystal forms, it tends to reject these impurities, which then

form a layer of concentrated impurities about the crystal. When adjoining

crystals meet, the impurities form a layer between the crystals of lower

melting point than the crystals themselves. This may greatly affect the physical

properties of the ice even though the amount of impurities is very small.

Melting will always be g in g at these boundaries between the ice crystals, and at ✓

a lower temperature than 32° F. Fresh-water ice becomes rotten as thawing,

006      |      Vol_IIA-0345                                                                                                                  
EA-I. Hansen-Linell: Fresh & Salt Water Ice.

starting at the inner crystal boundaries, separates the ice into separate

needles or columns. This ice is said to be “candled.” Thus, as a result

of this crystal structure in bulk, the physical properties of ice may vary

widely, especially when its temperature is near the melting point, depending

on the amount of impurities in the ice, the temperature, the age of the ice,

and the length of time that near-freezing temperatures have persisted.

        In formation of sea ice, the effect of the salt content is, of course,

very pronounced. Freezing of the water portions does not begin until a

temperature of 28.6° F. is reached in undiluted sea water, and the structure

produced is porous, containing pockets of brine from which solid salt crystals

begin to precipitate when the ice cools to about 17° F. (8). The structure and,

consequently, the strength properties of sea ice improve with time, as the

concentrated brine drains and as the salinity of the ice becomes gradually

smaller. Newly formed salt-water ice of relatively high salinity is flexible —

and elastic as compared to ice formed on fresh-water bodies (which is charac- —

teristically brittle), and it does not candle. Salt-water ice more than one —

year old is much tougher and stronger than young sea ice, but its surface is

much more likely to be rough. It is reported that when old sea ice becomes

sufficiently modified so that it approaches the composition of fresh-water ice, —

it too will exhibit a tendency to candle.

        From Soviet data, young sea ice requires about 1 2/3 times the thickness

of old sea ice to carry the same load, but this rule is very generalized. Lake

ice is usually assumed to be 2 to 3 times stronger than sea ice, although its

brittleness does not permit it to stand as much bending without cracking. River

007      |      Vol_IIA-0346                                                                                                                  
EA-I. Hansen-Linell: Fresh & Salt Water Ice.

ice is generally not quite as strong as lake ice.

        Any entrapped matter such as silt, clay, or plankton (2) tends to weaken

ice in the warmer periods because it absorbs sunlight and tends to cause

internal melting because of the heat produced thereby.

        Ice containing much entrapped air tends to be weaker than clear essentially

air-free ice. Tests by the Soils, Foundations and Frost Effects Laboratory

of the New England Division, Corps of Engineers, in 1946-47, on 6 by 6 by [ ?]

18-inch beams of artificial ice showed about 12% reduction in flexural strength

on beams cut from cloudy ice manufactured from ordinary tap water, as compared

with beams cut from clear air-free ice. Tests were performed at 10 ° to

13° F.

        Effects of Horizontal Stratification in Ice . The strength of ice may be

affected by development of horizontal laminae of variable properties. Variations

in temperature, temporary thaws, rains, formation of snow-ice, flooding, and

driving by the wind of salt spray onto the surface of otherwise relatively

fresh ice or snow will all form horizontal layers in the ice sheet, the effect

of which may be important in relatively thin ice but will be insignificant in

heavy ice.

        Another stratification development occurs in coastal areas where river

and stream inflows and tidal effects cause variations in the salinity of the

water during the ice formation period. An influx [ ?] of relatively fresh water

under the ice surface will result in rapid freezing to this surface, which may

have cooled to as low as 28.6° F. when normal salt water was present under the

ice. The same effect occurs in the polar seas during the summer thaw periods

008      |      Vol_IIA-0347                                                                                                                  
EA-I. Hansen-Linell: Fresh & Salt Water Ice.

when meltwater from the surface sinks down through holes and freezes onto the

cold undersurface of the ice pack. Such stratification in the lower part of

the ice sheet, where critical tensile stresses occur when the ice is loaded,

may be expected to have far greater effect on the over-all bearing capacity

than laminations which develop in the upper half of the sheet.

        In the polar ice pack much less regular horizontal structure layering

occurs when pressure causes rafting and buckling of the ice sheet.

        Effect of Vertical Cracks . Cracking of the ice sheet under the effect of

temperature stresses results in a pattern of vertical defects or discontinuities

distributed over the ice sheet. These do not ordinarily extend more than part .

way through the depth of the ice. Although they are conspicuous in the upper

surface of the sheet at low temperatures and may be readily visualized as a

possible cause of weakness, static-load tests by the Soils, Foundations and

Frost Effects Laboratory, in 1947, registered essentially no observable effect

of such cracks on the bearing capacity or failure action of the ice under a

load. Cracks formed due to the load showed very little tendency to follow the

existing partial cracks. However, these tests involved only single-load

applications, and it is reported that under heavy traffic, temperature cracks

do have an effect to reduce the load-bearing capacity of the ice sheet.

Cracks that pass all the way through the ice sheet seriously lower the load

capacity and are especially hazardous if they occur under a snow blanket, as

the snow may delay their refreezing and hide them from view.

        Temperature during Ice Formation . When ice forms very rapidly at extremely

low temperatures there is less opportunity for dispersion of the impurities

009      |      Vol_IIA-0348                                                                                                                  
EA-I. Hansen-Linell: Fresh & Salt Water Ice.

which are rejected by the ice crystals. Young sea ice formed at 14° F. has

entrapped about 5 parts per 1,000 salt, but that formed at −40° F. has 10 to

15 parts per 1,000. Differences in structure (and consequently of strength)

of the ice would be expected to result from such differences in actual volume

of included matter and the manner of its inclusion. It may be noted that the

more concentrated brine surrounding the freezing crystals during fast freezing

would tend to cause formation of the individual ice crystals at still lower

temperatures than in ordinary sea water, with possible effects upon the ice

properties.

        Residual Stresses . Internal stresses in ice specimens due to unadjusted

temperature effects, to stresses introduced i [ ?] obtaining and preparing test

specimens, or to external loadings of the ice sheet may well be in part re–

sponsible for variability of reported test results.

        Effect of Temperature during Test . Temperature has a very pronounced

effect upon the strength properties of ice, as shown in Table II.

010      |      Vol_IIA-0349                                                                                                                  
EA-I. Hansen-Linell: Fresh & Salt Water Ice.

Table II. Effect of Temperature on Strength of Fresh-Water Ice. —

Temperature of test, °F.	Strength tests, p.s.i.			Direction of load– ing in relation to crystal optic axes	Remarks	Source
	Compres– sion	Flexure	Shear
28	300			Perpendicular	3” to 5” square speci mens of St. Lawrence Ri– ver ice 5″ high; strees increased at approximate rates of 20 to 60 p.s.i./ sec.	(7)
14	693
2	797
	Tests with load applied parallel to crystal axes have been deleted
28-30		156		Perpendicular	3″ wide × 2″ deep beams of St. Lawrence River ice, 41″ span; loads applied at 14″ from supports; stress increased in in– crements at various rates averaging be– tween 0.175 and 1.4 p.s.i./sec.	(7)
14-16		240
28-30		184		Parallel ( a )
14-16		214
25		196		Essentially parallel ( a ) , ( b )	6″ × 6″ beams of air– free artificial ice, 18″ span; third point loading; stress in– creased at constant rates between 1.9 and 2.6 p.s.i./sec.	Soils, Fdns. & Frost Effects Lab. —
13		203
−8		214

( a ) Where applied load is noted as acting parallel to optic axes, in flexure tests, bending stresses

developed in beams act perpendicular to optic axes. ( b ) Some cur v ature of crystal structure existed because ice was frozen in containers from outside toward ✓

center, but this was minimized so far as possible in cutting out the test beams.

011      |      Vol_IIA-0350                                                                                                                  
EA-I. Hansen-Linell: Fresh & Salt Water Ice.

Table II. Effect of Temperature on Strength of Fresh-Water Ice. ( contd. ) —

Temperature of test, °F.	Strength tests, p.s.i.			Direction of load– ing in relation to crystal optic axes	Remarks	Source
	Compres– sion	Flexure	Shear
32		180	94	Parallel ( a )	Artificial ice flexure specimens 2½″ to 6″ deep, 2½″ to 5″ wide, 15″ to 30″ long; shear specimens 2½″ sq. and 6″ long; specimens failed in one to three minutes	(15)
2		-	90
−9		256	-
−10		-	115
23	220			Parallel (nor– mal to the natural ice surface)	5 cm. cubes of fresh – water ice; lower platten moved at constant rate of 0.1 mm./sec.; yield of upper load-measuring platten unknown	(12) —
14	252
5	354
−4	394
−13	488
−22	506
−31	584
−40	615
−49	665
−58	694
−67	725
−76	779

( a ) Where applied load is noted as acting parallel to optic axes, in flexure tests, bending stresses developed in beams act perpendicular to optic axes.

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EA-I. Hansen-Linnel: Fresh & Salt Water Ice

        Vitman and Shandrikov conclude from their test results, shown in Table II,

that the average compressive strength of ice increases more than four times

as the temperature decreases to −76° F. (12) . The data on change of flexural ✓

strength with temperature also shows an increase with drop in temperature,

though not as rapid as for compressive strength. Finlayson (5) found that

temperature has very little if any effect on the strength of ice in shear,

which is in agreement with the results of Horeth and Wilson (15) given in

Table II. Under a given rate of increase of stress, the rate of deformation

of the specimen rises (while the ultimate strength drops) with an increase

in ice temperature; thus, ice, acting like a highly viscous material, flows

more readily at higher temperatures.

        Effect of Rate of Loading on Strength Tests . Tests of ice specimens will

give different results depending on the rate at which the load is applied.

Numerous investigators have observed that ice will deform gradually under

a steady load. However, there appears to have been only little practical

investigation to determine the proper rates of load application for use in

correlating test values with the load-supporting capacity of ice.

        From flexure tests reported by Brown in 1926, it was concluded that the

modulus of rupture did not vary much at the different loading rates (7).

However, when his results at 14 to 16° F. are plotted together with a number

of flexure tests at 10° F. performed by the Soils, Fdoundations and Frost

Effects Laboratory in 1946-47, covering a wider range of rates of loading,

up to 7.65 p.s.i. per second, there is shown an apparent marked loss in

ultimate strength with increase in the rate of application of stress. It

is reasoned that if the indicated trend should be correct, then possibly the

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EA-I. Hansen-Linell: Fresh & Salt Water Ice

lower rates of stress increase permit plastic flow to occur at points [ ?] of

initial stress concentration, thus allowing adjustment of stress distribution

and higher breaking loads. It must be expected that the critical range

of loading rates, over which maximum changes of results occur due to varying

degrees of stress adjustment within the specimen, will be strongly dependent

on temperature. Finlayson found in shear tests on ice, that at temperatures

below 0° F., greater values were obtained when the load was applied rapidly (5).

        Effect of Orientation of Test Specimen . Since the bending stresses, which

act in an ice sheet under load and which control in part the bearing capacity

of the ice (the other factor being buoyancy), act in a direction parallel

to the ice surface, analyses of bearing capacity should, theoretically at

least, depend on tests in which specimens are stressed with their crystal

axes oriented correspondingly. Practically, this offers difficulties,

and if the bearing capacity of thick ice is to be determined from tests on

cores recovered from borings into the ice, it will probably be necessary to

establish an empirical relationship between strengths parallel to and at

right angles to the surface of the ice sheet.

        Size and Proportions of Test Specimens . As in testing concrete or

soils, the size and proportions of test specimens may be expected to influence

the results of tests on ice. Certainly a test on a small portion of a single

“needle” would not give the same results as a test on a collection of full–

length , “needles.” What the minimum desirable size of specimen should be

would be expected to vary with the type and condition of ice. However, there

seems to have been little productive study given to this phase of ice testing

as yet.

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EA-I. Hansen-Linell: Fresh & Salt Water Ice

       

Load-Bearing Capacity of Ice

        Records of Actual Ice Loadings . Records of the innumerable, and in

many areas regular, actual ice crossings which have been made with motor

vehicles, tractors, sleds, railroad trains, etc., appear to be a rather

meager source of data on the supporting capacity of ice for several reasons.

First, when such crossings have been made, there appears to have been only

rarely any attempt to record the actual conditions of the crossing, such as ✓

ice thickness and quality, weight of machine, temperature, size and shape

of loaded area, and presence of snow cover. Second, when such observations

have been made, they have been incomplete since all the factors involved

may not have been recognized. Third, there seems to have been little

interest in making such records generally available in publications.

Empirical rules have been developed on the basis of experience with crossings,

but it is difficult to trace these back to original records.

        Historical Military Rules . There are a number of old rules relating to

the load-bearing capacity of ice which mostly have their origin in military

engineering and are the result of observation and experience in the movement

of troops, equipment, and supplies across frozen bodies of fresh water.

The data in Table III are a modernized and improved version of these rules

(11). The rules should be considered to apply to fresh - water ice of good —

color and soundness, away from unsupported edges. The thickness measure–

ments should disregard any soft or poor quality ice on the top or bottom

of the ice sheet.

015      |      Vol_IIA-0354                                                                                                                  
EA-I. Hansen-Linell: Fresh & Salt Water Ice

Table III. Load Capacity of Ice.

Load	Thickness of ice, in.	Minimum interval, ft.
Single rifleman on skis or snowshoes	1.5	16
Infantry in single file, 2-pace distance ( a )	3	23
Infantry columns , ( a ) , single horses, motorcycles, ✓ unloaded sleds, or motor toboggans	4	33
Single light artillery place, ¼-ton truck, 4 × 4	6	49
Light artillery, passenger cars, medium 1½-ton trucks with total load of 3½ tons	8	65
2½-ton trucks, light loads	10	82
Closed columns of all arms except armored force and heavy artillery ( a )	12	98
Armored scout cars, light tanks	14	115
20-ton vehicles	16	131
45-ton vehicles	24	164

( a ) Minimum intervals shown are distances between files.

        Moskatov’s Empirical Method . Moskatov (10) has given a procedure for

determining required ice thicknesses for aircraft on skis which he calls the

“Method of Analogy.” Formulas derived by this method are given in Table IV.

The basic formulas for aircraft on skis have been adapted to the case of

wheels by use of a factor of 20%, which is used by the Russians. P is the

gross weight of aircraft in tons and t is the ice thickness in inches. The

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EA-I. Hansen-Linell: Fresh & Salt Water Ice

formulas are said to apply only for ice formed and maintained at a tempera–

ture below 16° F. At higher temperatures 25% greater thickness is required.

Table IV. Minimum Required Ice Thickness in Inches.

Type of ice	Aircraft on skis	Aircraft on wheels
Lake ice	t = (27/8)√(P)	t = (81/20)√(P)
River ice	t = (15/4)√(P)	t = (9/2)√(P)
Old sea ice	t = (27/4)√(P)	t = (81/10)√(P)
Young sea ice	t = (81/8)√(P)	t = (243/20)√(P)

        The formulas given in Table IV are simple and they indicate that the

carrying capacity of the ice varies as the square of the ice thickness;

this is confirmed approximately by elastic theory analysis. Design curves

from these formulas are shown on Figures 1 and 2, where they are designated

as “Russian (Moskatov) Empirical Analysis.”

        Elastic Theory Analysis . If a stationary load is placed upon the surface

of a floating ice sheet which extends out to a large distance on all sides

from the load, a deformation of the ice sheet occurs which is a maximum under

the loaded area and which extends outward in all directions, decreasing in

amplitude with distance from the center. When the deformation occurs, a

buoyancy force is caused to act upward on the bottom of the ice sheet. This

force is at any point directly proportional to the deflection at that p o int ✓

as long as the ice does not become submerged, with water flooding on top.

016a      |      Vol_IIA-0356                                                                                                                  

016b      |      Vol_IIA-0357                                                                                                                  


017      |      Vol_IIA-0358                                                                                                                  
EA-I. Hansen-Linell: Fresh & Salt Water Ice

At the same time, the bending strength within the ice sheet itself is

mobilized. The buoyancy and bending resistance forces combine to provide

the total supporting force for the applied load. (When, as may occur along

a shore line, the water drops away from under the ice leaving it suspended,

the ice sheet will have at that location greatly reduced load-supporting

capacity.)

        Since under static loading the buoyant force of the underlying water

at any point acts in exact proportion to the amount of deflection of the ice

sheet at that point, the latter may be assumed to have a perfectly elastic

support. If we may also assume that the ice sheet has properties approximating

those of an elastic slab, then the theories of elasticity may be applied to

compute stresses and deformations in the ice sheet and to determine thicknesses

required for given conditions of loading.

        As pointed out by Volkov, static loading of floating ice is more critical

than impact loading. Under an impact force, the ice is simply compressed

between the applied load [ ?] [ ?] and the underlying water; in order to develop

bending stresses, a definite volume of water must be displaced from under the

ice, near the area of load application, and under a sharply applied load the

time required for this movement to occur is insufficient. Shearing action

is usually not critical. Experience has shown that thin ice may be crossed

by a moving load when a stationary load would break through and also that

thin ice may sustain a stationary load for some time, then give away. Thus,

load-capacity studies may be based upon the static loading condition, except

as it may be necessary to apply modifications for wave action under moving

loads and for fatigue under repeated loadings.

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EA-I. Hansen-Linell: Fresh & Salt Water Ice

        For the condition of static loading, a comprehensive theoretical

analysis of the bearing capacity of floating ice has been developed by

Mr. H. F. Shea of the Soils, Foundations and Frost Effects Laboratory by

adapting to the case of an ice sheet formulas developed by Dr. H. M. Wester–

gaard for determining the stresses at the interior portion of an elastically

supported slab (14). In their general form, the formulas are not adapted

to giving quick answers since results must be computed. However, the

formulas permit analysis of a variety of combinations of loading patterns

and intensities which could not otherwise be approached.

        For uniformly loaded circular areas, these formulas are as follows:

        (1) Inside the area of loading:

f_x and f_y = (0.6517P/t2)[1.6713 + (3/4) log_et – logeB + (0.012B2/t3/2)] + (0.1516P/t2)[(r2/450B2)(cos2Θ)]

019      |      Vol_IIA-0360                                                                                                                  
EA-I. Hansen-Linell: Fresh & Salt Water Ice

        (2) Outside the area of loading:

        f_x and f_y = (0.6517P/t2)[1.6713 + (3/4) log_et – log_eB + (0.012B2/t3/2)] + (0.1516P/t2)[(r2/450B2)(cos2Θ)] )] c = √(1.6d2 + t2) – 0.675t when d < 1.724t c = d when d > 1.724t

        For uniformly loaded elliptical areas (or where a uniformly loaded

ellpitical area may be reasonably assumed), the following stress equations

apply:

        (1) Inside the area:

        f_x and f_y = (0.6517P/t2)[5.0372 + (3/4) log_et – log_e (a + b) – x2/(a(a + b)) – y2/(b(a + b))] ± (0.1516P/t2)[((b – a)/(a + b)) – (2ab/(a + b2)) ((x2/a2) – (y2/b2))] ✓

020      |      Vol_IIA-0361                                                                                                                  
EA-I. Hansen-Linell: Fresh & Salt Water Ice

        (2) Outside the ellipse, for, y = o, x = ≥ a ,

        f_x and f_y = (0.6517P/t₂)[5.0372 + (3/4) log_et – log_e (x + √(x2 - a2 b2)) – x/(x + √(x2 – a2 [suspect missing symbol here] b2)] ± (0.1516P/t2) [((a2 + b2)/(b2 – a2)) – 4b2x/((b2 – a2) (x + √(x2 + a2 – b2)]

        (3) Outside the ellipse, for, x = o, y = ≥ b ,

        f_x and f_y = (0.6517P/t2)[5.0372 + (3/4) log_et – log_e (y + √(y2 + a2 - b2)) – y/(y + √(y2 + a2 – b2))] ± (0.1516P/t2) [((a2 + b2)/(b2 – a2) – 4a2y/((b2 – a2) (y + √(y2 + a2 – b2))]

021      |      Vol_IIA-0362                                                                                                                  
EA-I. Hansen-Linell: Fresh & Salt Water Ice

        In these formulas the notation is as follows:

        f _x , f _y = bending stresses in p.s.i. at surface of ice at points

x , y on coordinate axes

        P = total applied load in pounds

        t = thickness of ice in inches

        e = base of natural logarithms = 2.7128

        B = ratio of radius of circular area to radius of standard

bearing plate (15 inches) = c/15

        r = radial distance from center of circular area to point

of stress investigation in inches . ✓

        θ = angle between x axis and line drawn between point of

stress investigation and center of circle

        a = minor radius of elliptical area in inches

        b = major radius of elliptical area in inches

        c = substitute radius of loaded area in inches

        d = actual radius of loaded area in inches

        a and b are further identified by the equation for an ellipse, (x2/a2) + (y2/b2) = 1 ✓

        For example, the stresses induced by a 60,000-1b. load transmitted

to ice 50 in. thick by a B-29 main dual wheel unit, assuming load is dis–

tributed equally over two circular areas, was determined.

        ( 1 ) Given the following data:

        Area (for one circular area) = 370 sq.in.

        Radius of circle, d = 10.9 in.

        Distance between wheel centers = 37.3 in.

        c = √(1.6d2 + t2) – 0.675t P = 30,000 lb. t = 50 in.

        P = 30,000 lb.

        t = 50 in.

022      |      Vol_IIA-0363                                                                                                                  
EA-I. Hansen-Linell: Fresh & Salt Water Ice

        (2) Using formulas (1) and (2) for the case of the circular areas:

        f = 37 p.s.i. when x = 0 and y = 0

        f = 26 p.s.i. when x = 37 p.s.i. and y = 0

        total f = 37 + 26 = 63 p.s.i. ✓

        In the above formulas, the following constants were assumed:

        Poisson’s ratio for ice = 0.365

        Modulus of elasticity = 1,294,000 p.s.i.

        Observed values of Poisson’s ratio are reported variously from 0.25 to [ 0138 ?]

0.38 and the value adopted above for the computations is, therefore, near the

higher limit. Stress-strain moduli have been reported by various investigators

from under 70,000 to over 1,500,000 p.s.i. Recent flexure tests by the Soils,

Foundation and Frost Effects Laboratory showed a tangent modulus value of

610,000 p.s.i. on a single specimen of artificial ice at 10° F. up to a

strees of about 25 p.s.i.; near the ultimate failure stress of 212 p.s.i., the

secant modulus (related to the origin of the stress-strain curve) was approxi–

mately 190,000 p.s.i. A value of approximately 400,000 p.s.i. was also

determined from the deflection of a naturally formed fresh - water ice sheet —

8.4 in. thick in a 27-ft. tank when loaded at approximately 10° F. Brown has

also presented considerable data on effects of temperature, and of rate and

range of loading, on stress-strain moduli (7), which indicate generally lower

values than the one adopted above for computation of the equations. Reduction

of assumed value for either Poisson’s ratio or modulus of elasticity in the

equations will result in an indicated increase in load capacity. Thus, the

formulas, as given above, are on the conservative side with respect to these

basic values.

023      |      Vol_IIA-0364                                                                                                                  
EA-I. Hansen-Linell; Fresh & Salt Water Ice

        Once the thickness of ice required for a given load, size of area, and

factor of safety has been determined, the thickness required for a different

load on the same loaded area and with the same factor of safety may be

computed from the relation that the thickness required varies directly with

the square root of the load.

        Preliminary Elastic Theory Ice Thickness Curves . Curves derived from

the elastic theory equations as presented are shown on Figures 1 and 2 for

aircraft with wheels and designated thereon by the phrase “Elastic Theory

Analysis.”

        The curves of Figures 1 and 2 have been computed with the following ice

strengths, assumed as conservative values for ice under the temperature condi–

tions noted on the figures:

        Hard, sound lake ice = 150 p.s.i.

        Hard, sound river ice = 125 p.s.i.

        Old sea ice (more than 1 year old) = 75 p.s.i.

        Similar curves could be computed for other types of loadings, such as for

tractors, sleds, aircraft with skis, and even structure footings. Figures 1

and 2 show results of a few actual loadings by planes and in tests.

        Comments on Elastic Theory Method and Thickness Curves . Although as yet

not complete k ly proved, the elastic theory equations which have been given

are considered the most accurate theoretical approach available. The constants

used in the equations are subject to considerable modification as more is

learned about the properties of ice. It may be that eventually more than one

set of constants will have to be used.

024      |      Vol_IIA-0365                                                                                                                  
EA I. Hansen-Linell: Fresh & Salt Water Ice

        For theoretical analysis purposes, the ice sheet has conventionally been

assumed to be in equilibrium under external forces and unstressed. This is ✓

likely to be far from the truth in the upper part of the slab. The stress

pattern in the upper part of an unloaded ice sheet due to temperature and

lateral forces must be very complex. That the stresses may be high is shown

by the cracking which occurs due to temperature alone. Fortunately, however,

elastic theory analysis shows that under an applied vertical load, the critical

stresses act in the lower portion of the slab where temperature stresses

are at a minimum.

        It should be emphasized that the curves apply at the interior of an ice

sheet; near the edge of a crack or open water, the load-supporting capacity

can be expected to be much less.

        It is also emphasized that the curves plotted on Figures 1 and 2 from the

elastic theory are preliminary, and are necessarily over-simplified. It is

obviously not possible to [ ?] adopt one strength value for fresh - water ice —

and one for salt - water ice and expect that all ice in all latitudes and —

locations will conform to either one or the other of those standards under

all the wide variety of conditions of salinity, temperature, and other factors

which will be encountered. Rather, the curves are guides to the approximate

answer, based on conservative strength assumptions. From the small experience

acquired to date, it is believed that the curves for factor of safety of 2.0

represent very safe thickness values under the limitations stated on the

curve sheets. Below the latter curves is a “zone of uncertainty,” extending to

below the curves from the Russian (Moskatov) Empirical Analysis. It is this

025      |      Vol_IIA-0366                                                                                                                  
EA-I. Hansen-Linell: Fresh & Salt Water Ice

zone of uncertainty which future studies of the bearing capacity of ice

sheets should explore. Eventually, there will probably be not just two but

a considerable number of curve sheets to cover the many possible combinations

of ice strength, temperature, salinity, and other variables. With such curves

and with the results of quick field tests of the characteristics of the ice

in question, using test apparatus of types now beginning to be developed,

accurate numerical evaluations of the load-bearing capacity of ice should

be possible. However, for the present, prudent procedure in critical cases

is to weigh together the empirical rules and formulas, the elastic theory

equations, and the promptings of judgment and experience.

        Effects of Moving Loads . Russian investigators have observed the

possibility of danger from development of resonance in waves created in the

ice sheet under moving loads and have actually encountered conditions in which

several machines in motion and passing each other in both directions set up

such wave action that the ice broke (6). They have reported that such occur–

rence becomes especially dangerous when the machines are traveling at speeds

corresponding to those of the propagation of the ice waves and that in such

a case a single vehicle can produce sufficiently strong resonant vibrations

to cause it to break. The Russians have prepared rules for speed and spacing

of vehicles to avoid this effect. On ice about 24 inches thick, over water

of the order of 16 to 33 feet deep, the Russians have found that at speeds

between 3 and 9 miles per hour a depression of the ice under the vehicle moves

at the same speed as the vehicle. At speeds above about 12 miles per hour,

wave vibrations are formed which spread far to the sides of the path, at speeds

which on this lake were found to be 19 to 25 miles per hour. They concluded

that on this lake initial speeds of about either 15 or 25 miles per hour should

026      |      Vol_IIA-0367                                                                                                                  
EA-I. Hansen-Linell: Fresh & Salt Water Ice

be maintained and that speeds intermediate between these rates should be

avoided. Overtaking of one machine by another should also be avoided, and

spacings between vehicles varying from 200 feet to 650 feet and more were

recommended, depending on the speed of movement and the strength of the ice.

Particular caution was advised near shores where complex wave effects may

occur.

        Repetition of loading under extensive operations causes ice to become

weakened. It is reported that one reason for this is the progressive

deepening of temperature cracks under the flexing action of heavy traffic.

Under such conditions, a desirable procedure is to provide sufficient area,

or alternate routes, so as to permit frequent changes in traffic lanes.

        It is also reported that ice will break up much more readily under

vehicles with low-speed motors than under those with high-speed motors,

because of the differences in frequency and intensity of vibrations trans–

mitted to the ice. Traveling parallel to major cracks must be avoided.

        Methods of Increasing Supporting Capacity of Ice. The bearing value of

an ice sheet may be increased by: (1) thickening the ice sheet as a struc–

tural member, and (2) distributing the load over a wider area of application.

        The ice thickness may be increased on the top by flooding the surface

in shallow layers, allowing each to freeze completely before adding the

following one, or the increase may be obtained naturally on the bottom of

the ice layer, over a longer period, by either keeping snow cleared entirely

from the surface or by packing the snow cover down solidly so as to increase

the rate of heat loss from the underlying water and thereby speed freezing.

Because even tightly compacted snow has insulating qualities, rate of thickening

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EA-I. Hansen-Linell: Fresh & Salt Water Ice

will be higher if snow is completely removed. If a heavy thickness of snow

covers the ice, it may sometimes be possible to assist the flooding procedure

by boring holes through the ice at intervals, the weight of the snow being

sufficient to submerge the ice and saturate the snow. However, flooding of

snow must carry through at least to the top of the snow cover, otherwise

the insulating effect of the unwet upper zone of the snow will permit the

underlying water-snow mixture to remain as slush for a long period without

freezing.

        Although superficial wetting down and/or compaction of the snow cover

sufficiently to produce a hard vehicle surface may result in a higher bearing

capacity of the ice sheet, it is likely that this results mostly from the

load distributing characteristics of the snow layer and the increase in ice

thickness which develops from the increased thermal conductivity of the layer.

        The load may also be distributed over a wider area by means of brush,

straw, plank, logs, or ice blocks laid on the ice, which may in turn be

covered with a layer of compacted snow to provide smooth travel and possibly

additional load distribution effect. Care must be taken to periodically

check ice thickness when such procedures are used, as the ice may melt on its

undersurface as layers are added on the upper surface, if the original ice

thickness has been in balance with the existing temperature conditions, if

the added materials have insulating qualities, or if currents are present.

        At the weak zone which exists where ice is not frozen to the shore, or

at open cracks, adequate bearing capacity is usually best obtained by bridging

over with timber or other structural materials (13).

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---

BIBLIOGRAPHY

1. Barnes, H.T. Ice Engineering . Montreal, Renouf, 1928.

2. Boorke, A. Morskie Ldy . (Sea Ice.) Moscow, Leningrad, Izdatelatvo

Glavsevmorputi, 1940. Polar Workers Library . Translation by E.

Olkhine in The Stefaneson Library, New York City.

3. Dorsey, N.E., comp. Properties of Ordinary Water Substance . N.Y., Reinhold,

1940. American Chemical Society. Monograph Series.

4. Finlayson, J.N. “Icebergs as ships,” Engineer , Lond. June 7, 1946,

pp.517-18.

5. ----. “Tests on the shearing strength of ice,” Canad.Engr . vol.53, no.1,

pp.101-103, July 5, 1927.

6. Ivanov, K. Ye., Kobeko, P.P., and Shulman, A.R. Deformatsiia Ledovogo

Pokrova pri Dvizhenii Gruzov . (Deformation of an Ice Cover under

Moving Loads.) Leningrad, Akademiia Nauk, S.S.S.R., Fiziko–

Tekhnicheskii Institutt, 25 July 1945.

7. Joint Board of Engineers on St. Lawrence Waterway Project. Report...November

16, 1926. Ottawa, Acland, 1927, Appendix F.

8. Malmgren, Finn. On the Properties of Sea Ice . Bergen, Grieg, 1927. Maud

Expedition, 1918-1925. Scientific Results , vol.1, no.5.

9. McConnel, J.C. “On the plasticity of an ice crystal,” Roy.Soc.Lond., Proc .

vol.49, pp. 323-43, Mar. 12, 1891.

10. Moskatov, K.A. “On posadke samoletov na led.” (Airplane landings on ice.)

Leningrad. Arktichaskii Nauchnyi-Issled.Inst. Trudy . T.110, pt.1,

art.5, pp.43-55. In Russian with English summary. Translated and

edited by Headquarters, U.S. Air Forces.

11. U.S. War Department. Operations in Snow and Extreme Cold . Wash.,D.C.,

G.P.O., 1944. Basic Field Manual FM 70-15.

12. Vitman, F.F., and Shandrikov, N. P . “Nekotorye issledovaniia mekhanicheskoi

prochnosti lda.” (A study of the mechanical strength of ice.)

Leningrad. Arkticheskii Nauchnyi-Issled.Inst. Trudy , T.110, pt.1,

art.7, pp.83-100. Translated and edited by Headquarters, U.S. Air

Forces.

13. Westergaard, H.M. Expedient Snow and Ice Roads . Wash.,D.C., G.P.O.,

26 September 1944. U.S. Army. Technical Bulletin TB Eng . 42.

029      |      Vol_IIA-0370                                                                                                                  
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14. ----. “Stress concentrations in plates loaded over small areas,”

Amer.Soc.Civ.Engrs. Trans . vol.69, no.8, pt.2, pp.831-86, 1943.

15. Wilson, J.T., and Horeth, J.M. “Bending and shear tests on lake ice,”

Amer.Geophys.Un. Trans . vol.29, no.6, pp.909-12, Dec., 1948.

       

Ralph Hansen and Kenneth Linell

Construction and Maintenance of Airfields in the Far North Regions

EA-I: (James D. Lang)

CONSTRUCTION AND MAINTENANCE OF AIRFIELDS

IN THE FAR NORTH REGIONS

       

CONTENTS

	Page
Introduction	1
Types of Airfields	3
Reconnaissance	6
Planning and Design	8
Construction	12
Grading	17
Preparation of the Subgrade	18
Paving	20
Snow Removal and Maintenance	20

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[EA-I: James D. Lang]

       

CONSTRUCTION AND MAINTENANCE OF AIRFIELDS

IN THE FAR NORTH REGIONS

       

INTRODUCTION

        The engineering aspects of the subjects of airfields, pavements, roads,

and drainage as they apply to the arctic and subarctic regions readily lend

themselves to treatment as a single discussion. While the actual construction

of these items follows the usual pattern normally employed in more temperate

regions, the engineering aspects do not. Seldom, if ever, does engineering

play such an important part as it does in the Arctic in the conception and

execution of any construction program. For airfield construction, in parti–

cular, never is proper engineering as important as when such construction is

contemplated for the Arctic.

        Assuming that for strategic, economic, navigational, or other reasons an

airfield must be built in a given area, flying characteristics of the site will

usually be the deciding factor in most areas of the world. In the Arctic, on

the other hand, more frequently engineering factors determine which one of

several sites will be chosen. Of course, both factors must be considered and

the best possible compromise be chosen, consistent with the mission.

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        Let us examine why engineering becomes so important. Arctic areas are

remote, relatively inaccessible, and devoid of facilities with which to per–

form any construction. The construction season is so short that any mistakes

or omissions are disastrous and may well result in the probable loss of one

full year in completion for each major error. The severity of the climate

creates problems of cold, wind, fog, snow, ice, permafrost, ice fields, and

other phenomena for which special measures must be taken. Any one or more of

the above conditions creates a requirement for extreme care in selecting and

examining sites and planning for the construction in minute detail. A firm

mental picture must be had of each and every move before any steps are taken,

otherwise valuable effort, time, and money will be lost, not only in determin–

ing the next measure to be taken, but probably in undoing false steps which

already may have been taken. Presolving problems and planning in detail so

as to permit completion of arctic construction at a minimum of cost in time,

[ ?] effort, and expense involves engineering of the highest caliber. It

cannot be overemphasized that construction such as is discussed herein involves

an engineering problem requiring the utmost skill in planning and execution

and that it is best to make haste slowly.

        Elsewhere in this encyclopedia are discussions of various natural phenomena

encountered in the Arctic. Before proceeding with this article it might be well

for the reader to familiarize himself with the general subject of permafrost in

order to understand what it is and how it behaves, also with the subjects of

surface and subsurface drainage. The engineer in the Arctic cannot undertake

any construction project involving excavation, drilling, pile driving, or even

just disturbing the earth’s surface without encountering either frost or

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drainage problems. Briefly, permafrost is a condition of eternally frozen

soil as distinct from eternally frozen icecaps and glaciers or from soil

subject to seasonal frost. Permafrost is beneath the surface and may exist

either as a continuous layer, or in lenses and pockets. How far the perma–

frost table may be from the surface varies from a few inches to many feet and

depends to a great extent upon the type of surface material above it, the

classification of the soil, and the subsurface drainage pattern. The ground

above the permafrost table is known as the active zone since it alternately

freezes and thaws, however, not necessarily to the same degree each year.

Ground water may exist below, within or above permafrost, and may be either

under pressure or free flowing, depending upon whether there are nearby high

elevations to provide the hydrostatic head or whether plains or areas of weak–

ness exist to relieve the pressure. It is obvious that during thousands of

years of direct exposure to extreme cold, nature has set up a balance, or

thermal regime, which exists within narrow limits. Any disturbance or new

outside influence will upset that regime. Construction activity provides the

influence to disturb e or upset nature’s balance. It is the engineer ’ s problem ✓

either to avoid disturbing the balance or to devise ways and means of diverting

the disturbed condition to his own advantage.

       

TYPES OF AIRFIELDS

        For military operations in the Arctic, three general types of airfields may

be involved. These are ice fields, light airfields, and heavy airfields , . Ice ✓

fields, as the term implies, involves construction of a temporary nature and,

of necessity, such construction is employed when hasty measures and rapid

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construction are required. In certain areas, of course, such as on an icecap,

these are the only fields possible. The principal requirements of the ice

field site selection are that the site must be able to support the mission for

which the field is being built; that the site must possess adequate flying

characteristics as to glide angles, wind direction, and grades; that the site

must be logistically supportable for the unit expected to operate therefrom;

that the terrain must be relatively level so as to minimize the amount of sub–

grading preparation; and that adequate quantities of loose snow must be avail–

able in order to provide surface materials for fine grading and compaction.

If a site can be selected which generally meets the foregoing criteria, the

problem of preparing the field becomes relatively simple. Methods of grading

and compaction of snow and ice utilize standard construction equipment and

techniques and present a problem quite similar to that encountered in grading

and compacting silty soils. An important element in selection of an ice field,

which has not heretofore been mentioned, is the selection of a site possessing

a suitable alternate landing area such that it may be developed into a permanent

field during the ensuing summer construction season should circumstances require

that flight operations be maintained for a prolonged period of time from the

general area. The ideal solution would be to select a location where this

permanent airfield could be built to utilize such structures and base facilities

as have been provided for the snow and ice field without the necessity of

extensive relocation of facilities or travel of unnecessary great distances

between the permanent airfield site and the base facilities.

        The second type of airfield, the light airfield, is one which again must

be selected and constructed usually in a minimum of time. This type of field

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involves the element of site selection to meet the requirements of mission,

flight characteristics, and logistic support. It also must meet the require–

men e t of enabling rapid construction of a base which can be used for year-round

operations. In general, the construction of a light airfield involves the

selection of a suitable flight area on which an airfield may be constructed,

utilizing nearby aggregate sources of free draining material, and spreading

and compacting these materials upon the undisturbed natur e al surface of the ✓

ground in such a manner as to avoid cuts. This type of field requires rela–

tively short and narrow runways, and can be completed with conventional methods

and equipment with little added difficulty over that which could be expected in

a more temperate climate.

        The third type of airfield, and the one which presents the greatest prob–

lem, is the heavy airfield. This installation requires a great deal of [ ?]

equipment, time, and effort and should be built only after the greatest delibera–

tion and consideration of all factors involved. The site selected must, of

course, meet the requirements of the mission to be performed and the flight

characteristics of the aircraft to be employed therefrom. These criteria

are of secondary importance, however, to possession of desirable engineering

characteristics. This is not to say that the mission and flight characteristics

can be neglected, but it is intended to mean that fields of lesser desirability

from the standpoint of these two characteristics may be selected if the

engineering character i s tics are otherwise more advantageous.

        Selection of any of the three types of fields discussed above naturally

rests upon proper reconnaissance of all available sites within the general

area from which the mission can be performed.

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RECONNAISSANCE

        The initial airfield reconnaissance can best be performed by air.

However, prior to such a move, a careful map study should be made to select

the general areas from which the mission can be performed and to eliminate

from those areas specific regions where mountainous terrain, lakes, sinuous

rivers, or other geographic factors obviously preclude consideration. A

systematic flight pattern should be set up and a suitable slow-flying

aircraft having good facilities for observation of the ground should be

employed. Experience in arctic areas has proved that observation of surface

condition will provide several excellent clues to the nature of subsurface

conditions which may be encountered. Areas covered by hummocky tundra, commonly

known as “nigger heads,” indicate the existence of a permafrost table near

the surface, poor drainage, and a general water-logged condition. This condi–

tion is true even where the existence of plateaus with sharply defined hill–

sides or terraces would otherwise indicate that there should be adequate

drainage from the area. The existence of a growth of birch trees indicates

thawed ground, i.e., an area which does not freeze between the permafrost and

the surface active zone. The existence of spruce trees indicates a permafrost

table relatively near the surface of the ground and poor drainage. On the

other hand, the occurrence of pine and fir trees indicates a well-drained

granular soil which in turn means that water flowing through this pervious

layer will have had a tendency to melt and lower the permafrost table. Such

sites are worthy of close investigation by ground parties and are indicative

of the most feasible airfield site. Areas covered by willows generally are

unsuitable since willows indicate the existence of ground water and a site

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likely to be troubled with surface ice during the winter months. Areas covered

by tree growth, which is irregular, and containing individual trees inclined

at odd angles indicate ground susceptible to swelling and frost mounds. Areas

devoid of trees and shrubs and which are covered by tundra and moss indicate

a high permafrost table, particularly such areas that have a “crackled” appear–

ance [ ?] or the octagonal designs characteristic of a high permafrost table.

Exposures of rock outcroppings indicate areas where the seepage of water

in the planes next to the rock is apt to cause a melting of the permafrost

and the development of subsurface channels of flowing water, which may make

construction exceedingly troublesome.

        Having selected a number of possible sites from the air, arrangements

should be made for further investigation of [ ?] these areas by ground

parties. Preferably a base of operations should be selected for the ground

parties from which several of the sites may readily be investigated. The ground

parties should consist of individuals who are experienced in the Arctic.

Parties should be equipped with normal survey instruments for complete and

detailed topographic surveys of the sites in question, also with light drilling

equipment and excavation tools for the digging of numerous test holes and

test pits, and also meteorologic equipment to initiate weather observations

throughout the entire period the party is in the area. It is extremely impor–

tant that a large number of test holes and test pits be dug to determine the

depth of the permafrost table; the characteristics of subsurface soils; the

existence, depth, temperature, volume, and direction of the flow of water; and

the nature of the natural insulating material which is found on the surface.

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Detailed notations should be made of all natural phenomena, carefully logged

and plotted on an area sketch. Test holes and test pits should be care–

fully back-filled with material as nearly similar to the original material

in order to avoid disturbance of natural conditions. It is important that

insulating materials be left on the surface so as not to induce subsequent

thawing in the area investigated. When conditions are encountered which

indicate the unsuitability of a given site for airfield construction, a care–

ful verification should be made and then further efforts suspended on that

particular site in order to conserve time for additional observations and

tests at other sites which have not been definitely eliminated. At best, the

time available for reconnaissance is limited so that as rapidly as site

selection can be narrowed to one particular location it should be done in

order that the maximum information may be developed on the final site prior

to committing the construction forces.

       

PLANNING AND DESIGN

        Following selection of a site, planning the construction operation must

be thoroughly, completely, and exhaustively pursued. Every scrap of engineer–

ing data accumulated during the reconnaissance must be reanalyzed and evaluated.

Maps, sketches, geological and geophysical reports, verbal reports, photographs,

long-range weather observations, ice tables, communication routes, available

equipment (both qualitatively and quantitatively), manning tables, shipping

capabilities, and the available time must be carefully reviewed until a firm

visualization of the construction problem is grasped with confidence. The

planner must then carefully fit these bits and pieces together, matching his

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capabilities against his minimum requirements. One of the major considerations

he must face is the provision of adequate living accommodations and opera–

tional facilities for the construction force. Construction of these items

is a major operation in itself and is a heavy drain on manpower and resources.

It follows that not one square foot of building construction should be pro–

vided, which is not absolutely necessary, and not one man should be permitted

on the construction site who is not fully qualified in his field and whose

full-time presence is not needed. No equipment should be brought to the site

unless the exact need for that equipment is anticipated beforehand.

        A second major consideration to be given during the planning phase is

that of establishing minimum requirements. It is a constant temptation to

add to the scope of any project. The planner must resist these tendencies

and enlist every means at his disposal to minimize and simplify his problem.

It is better to complete a spart o a n-like installation on time than it is to ✓

half complete an ideal plan. Time, manpower, and mat e é riel devoted to a non–

essential may mean failure to complete one element of the over-all project;

such failure might mean the loss of an entire year in obtaining final use of

the installation.

        To return to some of the engineering aspects of the planning, it is

essential that standard plans be selected or engineering designs be prepared

in advance of construction operations. This is where the data accumulated

during the reconnaissance and study phase of the project can be invaluable.

The drainage pattern, both surface and subsurface, is the key to the design

of the airfield. The landing strip, taxiways, parking aprons, and roads must

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be located and designed so as to create the least possible disturbance to

the natural drainage pattern. Where disturbance cannot be avoided, then a

solution must be adopted which will take advantage of, rather than attempt

to defy, the natural arctic phenomena known to exist. Deep and narrow drain–

age ditches must be planned to by-pass and reroute surface drainage from

construction areas. Subsurface patterns must be broken at critical points

several hundred feet away by providing deep ditches to be cut into the perma–

frost so as to create planes of weakness which will rupture and permit sub–

surface drainage either to be diverted away from the building areas or im–

pounded in induced ponds or ice fields away from the critical areas. Plans

should contemplate that natural insulating materials be left intact wherever

possible or be restored using similar natural materials stripped from other

areas remote from the airfield when disturbance cannot be avoided. The

grades, both longitudinal and latitudinal, of the runways and its appurtenances

should be set such that fills and not cuts are required in establishing final

surfaces.

        The building area for camp structures should be located downhill from

the landing field. Downhill, in this instance, is in terms of subsurface

drainage and not necessarily in terms of surface elevations. Construction

operation buildings, such as shops and warehouses, should be located between

the airfield and the camp. All structures should be located a minimum of one–

fourth mile away from the airfield, and preferably farther, up to one mile.

These distances are desirable to provide room for ex ap pa nsion, to minimize the ✓

effects on the runway of ice fog that will form in the vicinity of the heated

structures at temperatures below approximately minus 40 degrees Fahrenheit,

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and to minimize the effect on the subsurface drainage pattern both from the

standpoint of the effect of the airfield drainage pattern upon the building

area and vice versa. Structures themselves should be designed to minimize

shipping space required and to utilize local materials where possible. It

also is highly advisable to utilize prefabricated or precut designs to

minimize the manpower required at the site for erection.

        The design of the airfield landing strips, taxiways, aprons, and road

system will depend upon the type and nature of the aircraft and vehicles

which may be expected to operate upon them. It is beyond the scope of this

discussion to deal with the technical aspects of how this design is done, but

it is sufficient to note that standard engineering practice is followed to

determine the basic dimensions of the construction required and the nature

of the materials employed therein. It follows that maximum utilization must

be made of locally available materials, the nature and location of which were

determined by the reconnaissance. It also follows that the location of the

field must have been predicated upon the availability of suitable building

materials within a reasonable hauling distance of the final location desired.

One general aspect of the design, however, should be emphasized, and that is

that the subgrade materials to be employed in any kind of a fill must consist

of freely draining or highly pervious material, and that these materials must

extend all the way out to the edge of any such fill. There must be a means of

readily disposing of surface and subsurface drainage which may accumulate at

the edge of the fill. It is mandatory that the subgrade be designed to contain

well-graded gravel in its top and bottom courses in order to prevent mud,

either above or below, from working into the central portion of the sub g rade

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and thus lessen its free-draining characteristics.

        The discussion on planning and design has been devoted primarily to the

construction of heavy airfields since this type of field naturally presents

the greatest problem. However, the basic principles of planning and design

are also applicable to the construction of a snow and ice field, or of a

light airfield, or a road or highway.

       

CONSTRUCTION

        The initiation of actual construction operations is best approached by

moving to the site, either over land or by air, an advance construction party

consisting of personnel to complete more detailed investigation of the site

than was possible during the period of reconnaissance, and sufficient per–

sonnel to complete construction of base-camp facilities to be occupied by

the main body when it arrives.

        During the reconnaissance phase a number of drill holes and test pits

were dug to determine the general nature of the terrain and drainage pattern.

The number of such holes and test pits must now be multiplied many times.

For example, test holes must be drilled along the center line of each projected

runway, taxiway, apron, and road at intervals not exceeding 500 ft. and

preferably as close as 250 ft. Additional test holes and test pits must be

dug throughout the area intended for building construction. This general

area will have been selected during the planning phase, but it is a different

matter to locate each specific building on an exact site. The variation in

the permafrost structure may be so erratic that the shifting of a building 20

ft. one way or the other may avoid permafrost in the foundation excavation.

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When major structures such as hangars are to be located, it may be necessary

to drill on 50-ft. centers over an area of many acres to determine precisely

the most advantageous location. Additional drill holes must be driven at

each break in the terrain, on slopes having a variation of solar exposure,

along streams, edges of ponds, and particularly throughout areas expected

to be sources of borrow mat e é riel. The depth of test holes will vary. In ✓

general, the rule to follow is that in areas where the permafrost is not to

be dist ru ur bed, the holes will be driven only to the surface of permafrost. In ✓

other areas where removal of a certain amount of permafrost cannot be avoided,

holes should be driven at least 4 to 5 ft. below the lowest elevation of

the proposed foundation. For large structures these holes should be driven

to a depth equal to the distance from the hole to the nearest edge of the

foundation. Test holes along the center line of runways, taxiways, etc.,

must periodically be d e riven, say every 1,000 ft., to a depth of 50 ft. or ✓

more to ascertain the thickness and continuity of the permafrost zone which may

lie beneath the runway. Where uncommonly large quantities of free-flowing water

are encountered, extra holes should be driven to determine the direction of

flow and to attempt to gain a more adequate understanding of the rate of

flow.

        Let us turn now to the other group of the advance construction party

assigned the mission of preparing base-camp facilities for the main body.

The economics of such a move may not be at first apparent, but experience has

proved that time can be gained in the long run by holding to a minimum the

personnel so employed since they must exist initially without any base living

facilities. At the same time, the manpower thus saved and retained with the

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main body back at the base of operations can well spend its time in further

organization, planning, and making ready for the intensive effort which is

to follow. Holding the size of the advance party to a minimum also has

another advantage and this is to permit the establishment of well-defined

traffic lanes through which all traffic must thereafter be required to pass.

These traffic patterns must be rigidly [ ?] enforced. This is particularly

true on a site covered by muskeg or tundra since any disturbance to the surface

may induce a melting of the permafrost and the creation of a quagmire which

may have a disastrous effect on later operations. Where construction opera–

tions are confined to naturally exposed gravel areas, this matter of traffic

control is not important. A second carefully controlled situation must be

adopted at this time and rigidly enforced throughout the entire duration of

the construction operation. This control has to do with fire-prevention

measures. In the early phase of any construction operation in the Arctic, men

are not acclimated to the cold and will require additional heat which will

later not be necessary. Initial construction will be of a hasty nature and,

therefore, more hazardous from the standpoint of fire. Adequate fire-fighting

equipment will be lacking and conditions, in general, will be ripe for a major

conflagration which can be disastrous to subsequent construction operations.

The writer has learned through bitter experience that complete stocks of spare

parts, food, clothing, and construction data can be destroyed in a matter of

minutes. Full awareness of the disastrous effect of fires and the institution

of immediate measures to eliminate them can be a major factor in insuring

the successful accomplishment of the construction operations to follow.

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        Normally, it is most advantageous to move the advance construction party

to the site of operations during the time when the ground is still frozen.

Some equipment and heavy items of materials and supplies can be successfully

transported across the country without the necessity of providing special

measures for stream, lake, and swamp crossings. Clearing and surveying

operations can be accomplished more readily on ground in a frozen condition.

Construction of shelter and communal facilities for the main force, and

construction of access roads to the principal sites for borrow mat e é ri a e l are ✓

items of useful work that can be performed in the relatively mild weather

before the annual spring [ ?] break-up. Completion of these items before

the arrival of the main body means that a minimum of time will be wasted

upon arrival of that body and that full advantage may be taken of the best

construction season.

        The principal item of work and the greatest time consumer on an airfield

project is the runway itself. It follows, therefore, that this feature s should ✓

be the first item of major work undertaken by the main construction force.

During the planning phase an estimate of capabilities will have been made and

a decision will have been rendered relative to the advisability of completing

the subgrade and the pavement in one season or whether the paving can be

deferred one year to permit consolidation of the runway fill. The latter is

the better solution, but regardless of which solution is chosen, everything

must be subordinated to the one all-important element of completing the

scheduled amount of runway construction during the first season. Some curtail–

ment of elements of the project may be occasioned by encountering unexpected

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difficulties. The runway must be the last item to suffer a reduction in

effort.

        Taxiways and parking aprons, being closely allied to the runway, and being

also major items of work, should be given second priority and attention. The

grades established and the drainage pattern developed for the runway will

govern grades and drainage characteristics of the taxiways and aprons. These

problems may be mutually aggravated but should be resolved as items of impor–

tance second only to the runway.

        The provision of basic utilities, such as adequate water supply, sewage

disposal, power generation, roads, and fuel storage, have third priority.

        Living accommodations, including barracks, messes, latrines, washrooms,

and dispensaries, have fourth priority.

        Airfield operational facilities, including control tower, operations

building, crash rescue station, minor repair and shop facilities, are fifth

in importance.

        Administrative facilities, including warehouses, cold storage, maintenance

shops, major repair facilities, communications, and headquarters, have sixth

priority.

        Last priority should be given to schools, training facilities, chapels,

theaters, recreation, and other items of building construction which, while

necessary, are not of a vital nature such as to jeopardize failure of the

airfield mission.

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GRADING

        As previously discussed, it is preferable to avoid making cuts into

undisturbed areas susceptible to permafrost. However, upon occasion, certain

areas will contain humps or pinnacles which will have to be removed in order

to preserve reasonable longitudinal and latitudinal gradients without such

heavy fills as to make the task impossible to accomplish within the time

allotted. One of the best times to accomplish this grading is when the air

temperature is slightly less than 32 degrees Fahrenheit. Heavy rooters may

be used to loosen the surface material or blasting may be employed, and the

resultant material is removed by conventional hauling equipment. Later in the

season after daytime air temperatures have risen above freezing, it may be

advisable to accomplish grading in alternate areas on approximately three–

day cycles. The material can be loosened by ripping or blasting on the

first day. It can be left to melt and drain the second day, while the ripping

operation is conducted in a second area. Then, on the third day, the melted

material may be removed from the first area, and the cycle is repeated.

Building areas may be thaw e d to greater depths if time permits by using a

method commonly employed in gold dredging operations in the Arctic. This

method consists of driving a large number of one-inch pipes into the ground

on a grid pattern on 15- or 20-foot centers and pumping cold water through

these pipes until the ground has become sufficiently thawed to permit pipes

to be driven still farther into the ground. After the thawing has been accomplished

to the depth required, the loose material may be excavated by conventional

methods. Steam points may also be employed in lieu of cold water to hasten

the rate of thawing if the time schedule must be shortened. It is important to

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remember that after excavation in thawed ground has been completed, it is

necessary to restore immediately a layer of insulation to prevent the melting

process from continuing, for the site might become such a morass that it must

be abandoned.

       

PREPARATION OF THE SUBGRADE

        Assuming that a section of natural terrain is available which is a suitable

site for a runway, or that an area has been prepared by grading in the manner

described in the proceeding discussion, then the runway may be started by plac–

ing subgrade materials thereon, using conventional equipment and methods of

hauling in much the same manner as airfields or roads are prepared in more

temperate climates. The main difference to remember is that the undisturbed

frozen soil lying immediately beneath the subgrade has great bearing value only

so long as it remains frozen, and that a means must be provided of retaining

this high bearing value by sealing the frozen material from heat and flowing

water. Sealing against heat may be accomplished by preserving the natural

tundra or moss in its undisturbed condition or by covering the frozen base

with a much thicker layer of highly impervious gravel, crushed rock, volcanic

ash, or other similar material. It is worth while to note that a 3-inch

layer of moss or tundra is equivalent to approximately 36 inches of inorganic

material. This emphasizes the importance of retaining the former if at all

possible. Sealing against flowing water may be accomplished by providing

diversion channels for subsurface flows and by guarding against retaining

moisture within the subgrade by virtue of constructing in it a course of gravel

or crushed rock of granular size such that no moisture will be absorbed

019      |      Vol_IIA-0390                                                                                                                  
EA-I. Lang: Construction & Maintenance of Airfields

through capillarity. As previously discussed, the upper and lower layers of

the subgrade should consist of finer gravel to prevent mud from working

into the center section of the subgrade either from above or below. It is

important that no frozen material be placed in the subgrade. For this reason,

it is normal that subgrade preparation be accomplished during the warmer

months of the construction season.

        To enable the reader to have a better understanding of the thickness of

subgrade required, and hence of the work to be accomplished, a wheel design

load of 15,000 pounds or less will require approximately 30 inches of gravel

in the subgrade. A wheel design load of 60,000 pounds will require approxi–

mately 48 inches, and a wheel load of 150,000 pounds will require approxi–

mately 72 inches. Modern aircraft requirements tend to approach the largest

of these figures. This factor, taken in combination with the necessity for

employing fills rather than cuts, means that, throughout the length of the

entire runway, considerable settlement may be expected by compaction of the

subgrade during the first year or two of its existence. The subgrade will

be of varying depth, which means that there will be a differential settlement

unless extreme care is taken in placing the fill material in lifts of not to

exceed 6 to 8 inches during construction, and unless the material is

rolled with heavy sheep’s-foot and pneumatic-tired rollers. If proper com–

paction has been obtained during construction, and if time will permit, there

is no reason why paving should not be accomplished the first year. However,

limitations of time or equipment usually do not make this possible, so it is

best to treat the surface with a temporary asphaltic seal at the end of the

first construction season, and then the following year to regrade the surface

and proceed with the final paving.

020      |      Vol_IIA-0391                                                                                                                  
EA-I. Lang: Construction & Maintenance of Airfields

       

PAVING

        As a general rule, runways, taxiways, and aprons built to accommodate

present-day aircraft should be paved. Rocks and gravel picked up by pro–

pellers and jet engines are damaging to the engines and the airplanes them–

selves, as well as being dangerous to personnel in the area. Paving of arctic

airfields is best accomplished by using either portland cement or asphaltic

concrete. Limitations of time, equipment, and transportation, to say nothing

of plain economics, almost invariably rules out portland-cement concrete.

Also, since differential settlement may be anticipated, it is best to select

a pavement of the flexible type, of which asphaltic concrete is the most

suitable. Emulsions, cutbacks, and road oils are not recommended because of

the low temperatures which do not permit proper curing. Asphaltic concrete,

being a hot mix, can be prepared and laid even in temperatures below freez–

ing. It is economical, quick, and simple to place, with standard equipment

and with crews of moderate skill.

       

SNOW REMOVAL AND MAINTENANCE

        The problem of snow removal in the Arctic is obviously one which cannot

be neglected. However, it is not nearly as difficult as the uninitiated be–

lieve. Equipment for snow removal, such as is employed by highway departments

in our northern states, is entirely satisfactory. Snow crews must be organized,

trained, and kept in readiness, day or night, during the season when snowfall

may be expected. Snow removal operations are conducted [ ?] promptly so as to

avoid an accumulation of packed snow greater than three inches at any one time.

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EA-I. Lang: Construction & Maintenance of Airfields

Aircraft move with difficulty on loose snow, but without any appreciable

trouble on compacted snow. The limit of three inches of compacted snow is

established in order to avoid excessive slush and drainage problems during the

spring. Deep slush might necessitate the closing down of the runway for an

extended period. The melting of three inches of compacted snow, on the other

hand, presents a simple problem which can be handled without difficulty.

        Runways must be regularly inspected and maintained at all times. Major

repairs should be held over until the summer season when patching can be ac–

complished as is normally done in the United States. There will be occasions,

however, when emergency repairs must be made during the winter months. In

these instances, only temporary expedients should be employed, utilizing logs,

brush, landing mat, or built-up layers of snow and ice when no other means

are available.

       

James D. Lang

Excavations and Foundations

EA-I. (Al T. Donnels)

EXCAVATIONS AND FOUNDATIONS

       

CONTENTS

	Page
Gravel and Rock	3
Drainage	4
Disposal of Spoil	6
Airfield Foundation	6

001      |      Vol_IIA-0394                                                                                                                  
EA-I. (Al T. Donnels)

       

EXCAVATIONS AND FOUNDATIONS

        Excavation and foundation problems in Alaska vary greatly; however,

there are certain basic criteria peculiar to the country with which the planning ✓

or construction engineer should be thoroughly familiar for the successful

and economical accomplishment of a contemplated project. The subject

matter of this article is proposed to encompass large-scale excavation and

foundation factors encountered in the construction of airdromes and heavy

structures. These factors, however, are applicable to all construction

problems and should receive thorough consideration in the scope of planning.

        The specific location of a project immediately introduces or eliminates

certain problems for investigation. For example, south of the Alaska Range

no peculiar problems may be expected other than those usually encountered

in the northern United States. Permafrost conditions do not exist south

of the range. Depth of seasonal frost varies considerably depending on

ground conditions, vegetation, and snow coverage. Temperature conditions

are not severe and construction operations can be successfully carried on

from the first of March until December, frequently throughout the year. The

coastal regions (Prince William Sound area) have heavy snow and rough weather

from December through March and April. Average annual precipitation in this

area approximates 160 meters inches ; snow depths of 30 feet occurred in the winter ✓

of 1947-48.

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        North of the Alaska Range, particular attention is required for the

investigation of permafrost conditions and subsurface ice lenses. Contrary

to popular belief among persons not accustomed to the country, snow precipi–

tation north of the Alaska Range is comparatively light. Snow is dry and

powdery and little or no wind occurs in the interior. Blizzards, such as

are experienced in Montana, the Dakotas, and many other states, are not known

in central interior Alaska. Severe temperatures may be encountered from

December through February and March, with seasonal thaws occurring through

April and May. Construction weather is ideal from May to November, with

24 hours of daylight during the summer months.

        Excavation operations for air-strip construction may be started with the

spring thaws, usually in May, although frost is still retained in the ground.

This may be done by surface stripping with tractors and carryalls in systematic

passes over a large area, cutting down to the frozen ground, thus permitting

penetration of continued thaw. The operation is repeated upon return passes

of the equipment at such time intervals as thawing will permit. In this manner

the frost is followed downward to the desired grade in the gravel. Apparent

hopeless mud conditions will follow until free-draining gravel is reached.

Use of “pusher cats” should be anticipated for these mud conditions and difficult

traction on the frozen ground.

        Permafrost may be encountered anywhere, under the seasonal frost line and

near the surface, particularly where the ground is covered by tundra vegetation.

It is essential that all tundra, silt, and frost-bearing material (fine mate–

rial subject to frost action) be removed down to sound gravel base. It must be

remembered, however, that the original thermal regime should be restored

whenever possible. (See also “Engineering Problems and Construction in

Permafrost Regions.”)

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        Upon reaching the final grade for stripping operations, it is advisable

to excavate test pits strategically located to search out sand pockets and

frost-bearing material. These pits should be located on a grid pattern not

exceeding 200-foot intervals and depths of 3 to 5 feet. Unfavorable condi–

tions may require their location at more frequent intervals and slightly

greater depths to locate the existence of ancient slough courses which are

prevalent in the Territory and which have deposited fine sand and frost–

bearing silts. The slough courses may or may not be discernible from the sur–

face after stripping operations, but are readily traced by indication of

excessive mixture of fin d — e material in the gravel. All such material should ✓

be carefully removed and replaced with sound gravel. Removal of this

unsuitable material is accomplished by tracing out the slough courses with

tractors and scrapers.

       

Gravel and Rock

        Good gravel deposits are prevalent in practically all of interior Alaska

and are usually found at shallow depths under the surface. Natural gravels

are not too well-graded but are conducive to excellent subcase material.

Gravel found in the upper Tanana Valley is relatively small — too small for

satisfactory crushing operations. However, the gravel found closer to the

north slope of the Alaska Range contains a fairly high percentage of coarse

gravel (4 inches or more) that is suitable for obtaining high-quality crushed

rock. It has been determined that the size of the gravels found is dependent

upon the distance carried by glacial action from the bedrock of the Alaska

Range, the gravel becoming smaller with continued grinding action beyond the

rim of the ice.

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EA-I. Donnels: Excavations and Foundations

        Other rock deposits in the Tanana Valley area are basalt, granite, and

Birch Creek schist, of which the last mentioned is the most prevalent and

usually the most accessible. The Birch Creek schist varies considerably in

quality and, although it is not considered to be of the superior quality of

the basalts and granites, is usable for crushing and subgrade material. It

has a tendency to break up under compaction, forming a silty substance, and

will not obtain the interlocking ordinarily desired for good subgrade or

foundation construction. Economical availability may dictate its usage,

however, but it should receive careful consideration and analysis for its

contemplated use. It is not recommended as an aggregate in asphaltic or

portland-cement concrete.

       

Drainage

        The problem of drainage is one of the most important and frequently

one of the most troublesome aspects encountered in the North. The water

tables throughout the Territory have widely varying characteristics and

apparently have no known relationship to the river systems. The Tanana

Valley has a characteristically high water table, found 2 to 5 feet below

the gravel surface, varying slightly throughout the year, and flowing slowly

in a southerly or southeasterly direction. The water table in the upper

Nenana Valley (mile 373 on the Alaska Railroad) was found to be approximately

50 feet below the gravel surface and flowing in a northeasterly direction,

although the Nenana River is above the ground surface elevation at this

location and within 2 miles distance. The water elevation rose considerably

in the exploratory drill holes, indicating hydrostatic pressure, although

only sand and gravel were encountered down to the water level.

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EA-I. Donnels: Excavations and Foundations

        The river systems have built up their silt beds in such a manner that

natural surface drainage is away from, rather than toward, the rivers and

their tributary sloughs. It has been observed that the gradient away from

the rivers frequently occurs in the ratio of about 1 foot per 1,000 feet.

Extreme meandering of rivers and sloughs is a typical characteristic.

        Further drainage and flood difficulties may be experienced in the

spring of the year when rising rivers may wash above the surface of the ice,

thus progressively building up thicker surface ice and higher water until

the final ice break-up occurs. Surface drainage normally disposes itself

rapidly through the free-draining gravel which has been stripped of the

surface tundra. During the spring thaw, however, free drainage is prevented

due to the ground frost and, unless other provisions for surface drainage

are made, an accumulation of surface water may be troublesome until the ground

frost disappears.

        Excavation for structural foundation may necessarily be carried to

elevations below the normal water table, which adds materially to the con–

struction problems and costs involved, for which field conditions should be

studied in the development of plans and establishment of cost estimates. The

proposed procedure is to confine the operation to as small an area as possible

commensurate with available equipment, reducing the water table in this area

by the use of well points and pumps, and repeating the operation in the next

foundation section. The planning of subsurface installations such as base–

ments or other adjuncts should be based on full knowledge of the specific

subsurface and water-table conditions.

        No specific criteria exist for the solution of drainage problems. Each

development must be worked out individually. Sloughs and marshes afford

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EA-I. Donnels: Excavations and Foundations

disposal of drainage water, but the problem of flood and backup water is

present due to the usual flatness of the terrain. Freezing of drainage

culverts and outfalls may present difficulties in blocking the runoff during

the spring when alternate freezing and thawing occur. These should be

located to the best advantage of exposure to permit thawing during the day.

        Sewerage and effluent trunks require installation in heated utilidors

as being the only effective means of protection against freezing during the

winter.

       

Disposal of Spoil

        The matter of disposal of spoil is ordinarily not considered of major

consequence as it falls into the routine of ordinary earth-moving operations.

However, in the North conventional procedures frequently result in costly

effort. Planning of operations should, therefore, carefully include the

disposal of spoil to avoid its being handled more than necessary, or to

prevent spoil piles from freezing, thereby forming obstructions or detriments

to drainage or interference with other proposed operations. Removal of

frozen spoil may be difficult and expensive and unnecessarily adds to the

effort and cost of a construction project over the short construction season.

Spoil piles that require subsequent removal should be removed prior to the

onset of freezing weather.

       

Airfield Foundation

        Pavement evaluation was made on a concrete military runway constructed

during World War II, including the removal of slab sections for subgrade

bearing analysis. Large voids were disclosed between the subgrade and concrete

pavement due to settlement of the foundation. At certain locations the

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EA-I. Donnels: Excavations and Foundations

unreinforced pavement was unsupported for several feet and amazingly

withstood the impact of heavy planes without failure. Whether the settle–

ment of the foundation was due to faulty backfill containing frozen material,

or was caused by shrinkage of permafrost under the subgrade, or a combination

of both, is a matter of conjecture. The results, however, clearly point to

the importance of thorough investigation in dealing with permafrost and

placement of sound foundation material.

        In connection with the stripping operations previously described, a

major factor in determining the final grade of the stripping operations is

the determination of insulating coverage of nonfrost-bearing material to be

placed over permafrost areas with due consideration given to the possible

rising of the permafrost table under the fill. That is, it may be necessary

to strip into the permafrost and backfill with sound material to a depth

sufficient to obtain adequate insulation to prevent thawing of the permafrost

from heat absorption of the runway. It may be pointed out that recession of

the permafrost in the Tanana and Yukon valleys areas is a natural process,

and once thawed will not return. It is understood, however, that this

condition does not necessarily apply in some areas north of the Arctic Circle,

in which return of permafrost may occur after thawing.

        Extensive information is available from experiments and studies conducted

by the Permafrost Division of the Corps of Engineers for various types of

runways and other construction in connection with heat penetration into the

ground, depth of insulating coverage, etc. Excavation and foundation problems

encountered in the North are closely associated with permafrost problems and

engineers contemplating such operations are urged to avail themselves of this

complete source of information and visit the Permafrost Experimental Project

near the city of Fairbanks.

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EA-I. Donnels: Excavations and Foundations

        It is entirely practicable and frequently necessary to construct

airfields over permafrost owing to the existing pattern of the permafrost

areas and the usual limiting circumstances in the location of airfields.

However, in a certain selected location for an airfield in the Nenana Valley,

the runway and development site were found to be entirely free from permafrost.

When such conditions are encountered, it is indeed fortunate. Persons ex–

perienced in the characteristics of the North are able to ascertain with

reasonable accuracy the likely existence or nonexistence of permafrost by

observation of the forests and vegetation, sloughs, marshes, water table,

and general drainage.

        “Drunken forests” are the result of frost heaving, which causes the

trees to assume wild angles from vertical growth, appearing to have the tendency

of falling. Profuse growth of the native spruce stands occurs over permafrost

areas, especially where high water tables exist. The native spruce has no

tap root, which permits the tree to live within permafrost areas. A know–

ledge of forestry and plant life in the North may be of much assistance to

the engineer who is engaged in making preliminary examinations of possible

site locations.

        Sloughs and marshes usually indicate the presence of permafrost near

the surface. Areas subjected to good subsurface drainage are obvioualy

desirable in all respects and are less likely to contain permafrost. However,

such observations alone are not sufficient for determining the desirable

location of a “site.” A likely appearing location should be further explored

by test holes and other means applicable to the particular type of construction

contemplated.

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        Where extreme conditions of frost or ice action are observed, such as

ice or frost mounds, “drunk en forest,” and areas known to contain ice lenses,

these areas should be carefully avoided for any construction operations. An

upset of the natural thermal balance of the permafrost table by construction

operations may introduce insurmountable problems. The engineer confronted

with such a task should reassure himself with the necessary field research

and be familiar with the techniques of compensating for any upsets that would

appear probable in dealing with permafrost conditions.

        The importance of site selection and foundation construction must be

emphasized where permafrost exists, for there is always the possibility of a

building filling with ice and breaking apart due to peculiarities of permafrost

and ground water; upheaval and collapse of a building due to shifting of the

permafrost table caused by the building itself; or foundation and structural

failure, as occurred to the Federal Building at Nome and a major building at

Northway and similar occurrences to dwellings and other buildings throughout

the North.

        Subsurface ice lenses may be treacherous, for obvious reasons, if subjected

to thawing under the foundation of an air strip of building. For an engineer

who is involved with foundation problems a visit to the hydraulic mining

operations along the Steese Highway, north of Fairbanks, affords an excellent

cross-sectional view of subsurface ice lenses; here he can readily visualize

the potential hazards involved should he risk foundation construction without

full knowledge as to the presence of ice lenses.

        The total importance of determining the permafrost and subsurface ice

conditions in connection with foundations lies in the simple fact that heat

penetration into the ground may eventually reach the permafrost, causing

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EA-I. Donnels: Excavations and Foundations

thawing and subsequent settlement. In the case of airfields, sufficient

insulating earth coverage may readily be constructed to compensate for the

heat absorption at the surface. As previously described, the techniques of

such construction and required depths of insulation are obtainable from

precise experimental data available from the Permafrost Division, Corps of

Engineers.

        In the case of building foundations, the heat penetration into the

ground is normally continuous and depths of heat penetration are dependent

upon the size of the building and other factors. For example, a small building

or narrow building permits the influence of exterior temperatures under the

foundation to a greater extent than would occur in the case of a building

covering a large area. Also, the problem may be complicated by a shifting

of the permafrost table, which may be expected to drop on the south side of

the building due to the sun’s rays on the wall surface, and rise on the north

side which does not receive the sun’s rays.

        The extent to which subsurface explorations may be necessary greatly

depends upon the type and permanence of the buildings contemplated. Thawing

temperatures may be expected to penetrate the ground beneath a building at

the rate of from 3 to 5 feet per year under average conditions for depths

within the limits of average building construction. Thermal penetration

becomes slower with increased depths. Where permafrost is know to exist at

20- to 3 0 -foot depths, no serious foundation settlement would be expected ✓

within the usable life of temporary or semipermanent installation. Numerous

military installations constructed over known permafrost areas during the war

have shown no indication of settlement up to the present time. It is probable

that sufficient time has not elapsed to permit thawing temperatures to reach

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EA-I. Donnels: Excavations and Foundations

the permafrost and cause settlement to a perceptible degre — e . ✓

        The element of time is usually a major factor in the construction of

temporary or semipermanent military installations. For a construction

program of this nature, extensive foundation examinations would be imprac–

ticable and unwarranted.

        Heavy structures or buildings of a permanent character, such as hangars,

power plants, or comparable major buildings, to which settlement would

seriously endanger structural or mechanical alignments, should not be con–

structed over permafrost. The foundation conditions for such structures

should be thoroughly investigated and the structure located in an area

devoid of permafrost.

        The following test was made to ascertain whether or not appreciable

settlement would occur upon thawing of permafrost-bearing gravel and to

determine to what extent such permafrost-bearing gravel could be used for

foundation.

        The ground was stripped of all surface material to sound gravel within

the permafrost table over an area sufficiently large to conduct the test

properly, and depressed sufficiently to contain water. Two 1-inch diameter

pipes about 5 feet long were welded to the inside bottom of a 55-gallon steel

drum in such a manner that the pipes were parallel, about 2 feet apart and

extending out of the open top of the drum. The drum was then filled with

concrete to obtain substantial weight. Welding the pipes to the bottom of

the drum prevented transmission of movement to the pipes from shrinkage of

the concrete. A heavy steel leveling plate was placed on the frozen gravel

surface and the concrete-filled drum placed thereon. Two pipes were securely

embedded into the permafrost on each side of the drum in vertical position.

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EA-I. Donnels: Excavations and Foundations

A rigid steel angle was secured between these pipes. The steel drum was

adjusted to position so that the pipes extending therefrom were aligned with

the angle beam. Two micrometer dials (Ames) were secured between the angle

beam and the pipes extending from the drum in such manner as to register

movement of the drum. Water was placed in the depression, partially submerging

the drum, and heated by steam from a portable boiler. Care was exercised to

apply heat evenly around the drum to obtain uniform settlement. The results

of the test indicated a settlement of approximately 1 inch in 5 feet of thawed

ground.

        Upon examination, the frozen gravel might give the impression that thawing

of the frost crystals in the voids would have little or no effect on the

shrinkage of natural compacted gravel, thus leading to the false assumption

that such material would be conducive to good foundation.

        The results of the above test, however, indicated that a settlement of

6 inches or more may be anticipated in event of thawing of a permafrost lenso

of average thickness encountered in this particular area. This a mount of ✓

settlement could obviously be disastrous to a large rigid structure.

        Such ground would afford suitable foundation for light frame structures

of the temporary or semipermanent type to which no serious damage would result

that could not readily be repaired in event of slight settlement. This effect

should be considered in the installation of plumbing and utility connections.

        The selection of a site location for a major structure entails the primary

consideration of locating an area void of permafrost. If such an area cannot

be located, the permafrost under the foundation area must be thawed which

involves a difficult and time-consuming operation. The exterior foundation line

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line should not be less than 20 feet horizontal distance from a permafrost

body. The permafrost occurs in the form of islands or “kidneys” interspersed

with void areas. The determination of these void areas involves a considerable

amount of subsurface exploration. In the course of master planning, the plan–

ning engineer should allow adequate flexibility to permit the shifting of site

locations, if possible, to such a void area.

        Exploration for the existence or nonexistence of permafrost by drilling

alone is exceedingly time-consuming. In order to speed up this operation,

the following method was satisfactorily utilized for establishing the location

for a hangar having 90,000 square feet of floor area.

        The proposed building site was surveyed and s taked out (exterior foundation ✓

line plus 20 feet). At each corner and at quarter points on each side and at

the center, railroad rails were drive d n with a drop-hammer pile driver. Explora–

tion was carried to a depth of 60 feet, as it was considered that no permafrost

would exist beyond this depth, or if it did, it would not be reached by heat

penetration. Upon striking permafrost, no further penetration of the rail

could be obtained. Permafrost was struck along one entire side of the building

site and partially along the two adjacent sides. No permafrost was found else–

where on the building site. This indicated that the permafrost lens out somewhat

diagonally across approximately one-quarter of the building site area. It then

became necessary to locate and plot the edge of the permafrost lens. The dis–

tance between the rail points which straddled the edge of the lens was bisected,

and a rail driven at that point. This procedure was repeated on a grid pattern

until the edge of the lens was located to an accuracy of approximately 5 feet.

Concurrently with the driving operation, well drills were used at strategic

locations to penetrate through the permafrost, measuring depth and thickness

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of the lens, and also to verify the conditions where indeterminate rail

driving was encountered due to striking dense material or rocks. The tops

of the lenses were found at 15- to 30-foot depths and were from 20 to 30 feet

in thickness and usually tapered off toward the edge of the lens.

        Establishment of the exact location of the permafrost lens afforded

knowledge of the required distance and direction to shift the building site.

Shifting the building site off the permafrost area also introduced the possi–

bility of moving the opposite side of the building onto another permafrost

island, which condition required investigation. Further possibilities as to

existence of permafrost islands within the building area also required investi–

gation. This method required comparatively few drill holes and the entire

work was accomplished in about two weeks.

        The rail-driving method had not been previously attempted and some experi–

menting was required to effect efficient operation. Rails were cut from 10-

to 15-foot lengths, which was the maximum length that could be placed in the

driving leads. Upon driving to ground surface, a new length of rail was placed

in the leads and spliced to the driven rail by welding. Some difficulty was

experienced in the welds breaking or the rail bending under impact of the hammer.

The development of a more efficient splice and the improvision of a lead guide

to prevent bending corrected this difficulty. The driving method could be

greatly improved and the operation speeded up considerably with the planning

of an efficient equipment setup and manner of splicing. Several pile drivers

with swinging leads and well drills are required to cover efficiently the extent

of the work.

        The use of geophysical equipment was considered for determining the location

of permafrost. However, the time involved for procurement of special equipment

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and experienced operating personnel, together with the fact that such an

operation would be experimental with questionable reliability of results,

precluded its use d for the above operation. It is possible that the use ✓

of geophysical equipment for such purpose on extensive operations might

prove of extreme value in saving time and labor, and introduce further

knowledge of subsurface conditions.

        In the event that it is not possible to obtain a site location entirely

devoid of permafrost and it becomes necessary to thaw out such an area, the

site should be located to minimize the quantity of permafrost to be thawed.

The method of thawing permafrost by percolation of cold water as observed in

connection with mining operations in the Fairbanks and Nome areas would

ordinarily not be considered practicable for construction operations owing

to the time involved, unless a long-range, extensive construction program was

contemplated.

        Although the experience of the writer did not entail the necessity of

performing thawing operations, as it was easier to move off permafrost areas,

a planned operation was conceived by driving steam points on a grid pattern of

10 to 15 feet over an area of not more than 100 feet square and connected to a

header system to which steams would be supplied from portable steam boilers.

It was calculated that this interval of steam points would adequately raise

the ground temperature to permit rapid thawing and permit continued penetration

of the steam [ ?]

points by hand-driving similar to the method used on cold-water points, which

consists of a weighted mandrel slipped over the projecting pipe similar to

that used in driving steel fence posts.

016      |      Vol_IIA-0409                                                                                                                  
EA-I. Donnels: Excavations and Foundations

        The primary subject of excavation and foundation requires a complete

correlation with all other factors in planning and construction. Such

planning may be required in considerable detail for the effective operation

of the work. An extensive amount of preliminary field investigation may be

necessary for the development of master and detail planning. The procurement

and transportation of equipment, materials, and personnel involve the thorough

planning of logistics, particularly in connection with the heavy equipment

necessary for excavation and foundation construction like power shovels, tractors,

carryalls, dozers, rock crushers, and trucks. Shipping and unloading facilities

for quantities of such equipment at Alaska ports are limited. The ports of

Seward, Whittier, and Anchorage are the only territorial ports with railroad

connections. These ports at present (1949) have limited dock facilities. The

port of Anchorage is usually icebound during the winter months. Inland trans–

portation is subject to limited highway facilities to off-rail points.

        In addition to the solution of transporting such equipment, it becomes

necessary to set up adequate shops and self-sufficient facilities for equipment

repair and maintenance. Excessive equipment deadlines have been evidenced on

past operations for lack of adequate planning for this phase of work.

        Concurrent with the above requirements are those necessary for the housing

and care of personnel. These further tax the facilities for mat e é riel procurement.

        Air transportation in the North is vital. In remote sections of the

territory, the primary operation of grading off a temporary airfield for use by

medium-sized planes will be found to enhance greatly communications and security

in providing the means of obtaining much needed supplies when starting and con–

ducting operations on a project.

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EA-I. Donnels: Excavations and Foundations

        All of these considerations require precise planning and coordination

to effect full advantage of operations during the relatively short construction

season. The failure of any one major factor may easily result in the partial

or total loss of a year’s operation, which delay may be the determining

element of success or failure of the project.

       

Al T. Donnels

Emergency, Temporary, and Semi-permanent Housing for Polar Areas

EA-I. Palmer V. Roberts

EMERGENCY, TEMPORARY, AND SEMIPERMANENT HOUSING FOR POLAR AREAS

       

TABLE OF CONTENTS

	Page
Emergency Housing	2
Principles of Design of Temporary and Semipermanent Buildings	11
General	11
Insulation	14
Condensation	20
Methods of Condensation Control	23
Ventilation	28
Temporary Housing	30
Semipermanent Housing	35
Prefabricated Housing	35
Modern Prefabricated Buildings	40
Bibliography	47

Unpaginated      |      Vol_IIA-0412                                                                                                                  
EA-I. Roberts: Housing

       

LIST OF FIGURES

		Page
Fig. 1.	Steps in building a snow cave	3-a
Fig. 2.	Steps in domeshaped snowhouse construction	6-a
Fig. 3.	Steps in domeshaped snowhouse construction-continued	6-b
Fig. 4.	Steps in earth and wood house construction	30-a
Fig. 5.	Typical section Quonset hut (Barrow)	40-a

001      |      Vol_IIA-0413                                                                                                                  
EA-I. Palmer W. Roberts

       

EMERGENCY, TEMPORARY, AND SEMIPERMANENT HOUSING FOR POLAR AREAS

        It is a fundamental principle in building design that the best buildings are

those so constructed throughout that they meet the basic requirements of the region

while also serving the operational requirements of the users. The type of design

selected depends greatly on local soil, drainage, and climatic conditions. The

details of the design depend greatly on the materials locally available or trans–

portable to the area. Therefore, standards for the construction of shelters and

buildings in the Arctic and Subarctic, and particularly where permafrost is present,

will vary greatly from those applicable to the temperate and tropic zones. In

areas where permafrost does not exist, the construction of housing may be similar

to that of any region of cold winters where seasonal frost action is severe.

        The selection of an appropriate type of housing in the Arctic is perhaps best

approached by the consideration of three factors: the length of time the build–

ing is to be occupied, the time required for construction, and whether or not

local or transported materials are to be used in the construction.

        Various classes of housing may be defined on the basis of these factors as

emergency, temporary, semipermanent, and permanent. The following definitions have

been arbitrarily established for the purpose of providing an orderly approach to

the subject of arctic housing:

002      |      Vol_IIA-0414                                                                                                                  
EA-I. Roberts:

        Emergency: to be occupied for a period ranging from overnight to possibly

as long as one year, and capable of being completely constructed in less than

half a day from materials available on the site, or with lightweight materials

brought in for construction purposes.

        Temporary: to be occupied from one to five years and requiring approximately

one day’s effort for construction, using local or imported lightweight building

materials.

        Semipermanent: to be occupied for at least 15 years, requiring more than

one day’s construction effort, and utilizing lightweight prefabricated materials

brought into the area for the building.

        Permanent: to be occupied for at least 25 years, requiring considerably more

than one day’s effort for construction, and using high-quality prefabricated or

on-site fabricated imported building materials of a standard nature.

        Discussions here will be concerned only with the first three classes of

buildings, which are generally of one-story construction. Permanent buildings,

of course, follow the same principles; but as this type of construction largely

conforms to standard construction in the northern United States, it will not

be dealt with in this discussion of arctic housing.

       

EMERGENCY HOUSING

        In an emergency, many [ ?] types of shelters and windbreaks can be constructed

from materials at hand. One may first utilize the materials with which one has

landed. If one came by plane, any of the easily removable sections, such as the

cowling, will serve for construction. The cabin of a large plane will serve as

an excellent temporary shelter. Similar use may also be made of stranded vehicles

and boats. Any large piece of fabric may be used as a shelter roof, and the sides

003      |      Vol_IIA-0415                                                                                                                  
EA-I. Roberts: Housing

can be built up with snow blocks, sod, etc. Snow, soil, stone, bones of large

mammals (whales), and wood, if available, will furnish building material for

housing once the immediate crisis is over.

        The types of shelter that may be improvised by one or more men are numerous.

Tents may be made from shelter halves or parachutes. If deep drifts are found,

snow caves may be built to good purpose. Walls of snow blocks will serve as wind–

breaks. Standing or fallen trees may be most useful for individual survival.

Within a shelter, some form of insulation must be placed under a fire if the

floor of the shelter consists of snow; good insulation is required under a sleeping

bag or other bedding.

        Snow Cave . One of the simplest forms of shelter is the snow cave. Such a

cave can often be built by two men in about two hours. The only tools required

are shovels. A square of canvas or other fabric may be useful to cover the door.

        A site is selected on a reasonably steep slope where the snow has lain

in place long enough to have become compacted. ( See Figure 1. ) A working shelf is ✓

cut into the slope or drift, and then a small cave two feet by two feet is ex–

cavated back for a foot or two; this becomes the doorway. The cave proper is then

started, working gradually upward, as the floor of the cave should have an upward

slope , away from the doorway. The easiest procedure may be to cut the snow into —

blocks and cast them out through the doorway and down the slope. The ceiling should

be shaped into an arch or done. This allows condensation to run down the walls,

provides standing room in the center, and serves to strengthen the shelter.

        The final cave size, to accommodate three or four people, should be about five

feet high, nine feet long, and eight feet wide. A sleeping place is arranged by

having the level of the bed platform at least one foot above the floor, which

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004      |      Vol_IIA-0417                                                                                                                  
EA-I. Roberts: Housing

should be terraced. After this, the shovels and all personal equipment are brought

into the cave, a ventilating hole is cut upward through the roof, and, if the

entrance is not low enough, a square piece of fabric is placed to form a door.

If the bed platform is some two feet higher than the top of the entrance, it

will not be necessary to close the door, unless there is a strong wind that

forces gusts into the cave. For, cold air being heavy, it will remain at a low

level so long as the upper parts of the cave are filled with warm air.

        A snow cave has many advantages over the tent, among them that the material

to be transported is lessened by the omission of the tent and stove. Once the

cave is occupied, the air within rises to a temperature above freezing and remains

there as long as the cave is occupied, no heating being required except that fur–

nished by the bodies of the occupants. In the daytime no lighting is needed,

for sufficient light filters through from overhead; at night a single candle

gives enough light, because of the high reflecting qualities of walls and ceiling.

        Snow caves have been successfully used in the Arctic as well as in high

mountains. Instruction in their construction and use should form part of the

normal training of polar travelers.

        The dome snowhouse is built from domino-shaped blocks of wind-pressed snow.

These blocks are cut four to six inches thick, twenty to forty inches long, and

from twelve to twenty inches wide. Such blocks, depending on the density of the

snow, weigh from fifty to a hundred pounds and are strong enough to support not

only their own weight but also that of the blocks resting on them. It is of prime

importance that the snow be of the proper consistency. This can be determined

by driving a blunt but slender rod into a snowbank with a steady shove. If it

sinks in slowly with an even pressure, the snow is of the proper consistency for

005      |      Vol_IIA-0418                                                                                                                  
EA-I. Roberts: Housing

use in construction. Snow that is too soft crumbles in handling; if layers are

of uneven hardness the blocks may split; if the snow is too hard the blocks will

be poor insulators and the house will be cold.

        In the building of a snowhouse the only tools required are a knife with a

blade fourteen to twenty inches long for cutting blocks, a shovel for piling snow

on the completed house, and a rod for determining the consistency of the

snow. For cutting blocks from very hard snowdrifts, a carpenter’s saw is good.

Three or four men make a desirable building team: one cutting the blocks, a second

carrying the blocks and chinking cracks, and the third working inside the house,

building. A fourth man, if available, may work outside the house, chinking cracks

between the blocks, but not following the builder too closely, for snowhouse

walls are fragile until the soft snow pressed into the cracks has had time for

setting into snowcrete.

        The best location for building a snowhouse is on a level part of a well–

compacted drift where the snow is more than three feet deep. This depth provides

ample insulation and permite tunneling the entrance under the walls to a well in

the floor, which, as later explained, is the preferred entrance construction. If

this desired depth of snow is not available, then an entrance porch may be built

from snow blocks aboveground, whereupon it will be necessary to close the house

door at night, as a gravity differential will not be available for keeping the

cold air out. If the house is to be built on bare ground, a floor of at least

a five-inch layer of compacted snow must be placed to form an insulating layer;

for bare ground radiates cold.

        The usual snowhouse is dome-shaped, with a five- to seven-foot ceiling, and

has a diameter equal to twice its height. A house can be built to accommodate ten

006      |      Vol_IIA-0419                                                                                                                  
EA-I. Roberts: Housing

people, if the snow is good and the builder skillful; but such a house will have

to be so high that it will necessarily be cold, since the warmest air will gather

up in the dome where it is of no comfort to the occupants and threatens to melt

a hole in the snow roof.

        The first step in building a snowhouse is to lay out a circle. For a

✓ twelve-foot house this will have a six-foot radius. ( See Figure s 2 . and 3) The first row

of blocks are stood on edge, fitted together around the line of the circle, and

tilted slightly inward. The first course is tapered in height by cutting with

the knife, and succeeding blocks are laid in a continuous spiral, tilting farther

and farther inward until there is only a small opening left at the top of the

dome. Then the builder carves what is named the king block, and, from the inside

of the house, thrusts it out edgewise through the aperture; he then levels the

block and lets it sink into place. The builder on the outside of the house chinks

the openings between the blocks, gently but firmly, with loose snow, which begins

to set into snowcrete. After all blocks are set in place, the final chore is to

throw loose snow over the completed house with a shovel, taking care to get none

struck on the very top of the dome. This snow slides down and forms, as it

finds its natural angle of repose, a banking perhaps three feet thick at the

base, thinning upward.

        The door is provided by tunneling under the wall to the well inside the house.

A bed platform, occupying about two-thirds of the interior floor space, is built

of snow. The level of this platform is at least eighteen inches above the top

of the entrance, as this is required for gravity control of the temperature

within doors. This eighteen-inch minimum difference relationship between the

level of the bed platform and the entrance is always strictly adhered to, other-

006a      |      Vol_IIA-0420                                                                                                                  

006b      |      Vol_IIA-0421                                                                                                                  


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EA-I. Roberts: Housing

wise a closure for the door would be required.

        For sleeping, the bed platform is covered with some good insulator, such

as a double layer of skins, with the fur side down on the bottom skin and up on

the top one. This arrangement prevents body heat, which would cause thawing,

from passing to the snow underneath.

        Warmth for the snowhouse is provided by the use of an alcohol or seal oil

lamp, or by a kerosene or gasoline stove. The colder the weather the hotter the

house may be kept without melting the roof, for the cold from outside penetrates

into the snow blocks to meet the heat from within and prevents melting. To glaze

the inner wall surface, the temperature in the house is raised high, immediately

after bedding has been placed in position; the inner surface of the walls, which

absorbs moisture like blotting paper, now becomes spongy. Then the fire is put

out, or a large hole is made in the roof, and the inner wall is allowed to freeze.

This glazes the inside with a film of ice, provides a hard protective inner sur–

face which does not crumble when the occupants touch it, and greatly increases

the strength of the dome.

        Ventilation is controlled by the gravity method. A wooden chimney or

vent is placed in the dome, a little off center. When the lamp or stove is not

burning, the vent is closed by stuffing mittens or a cloth in the vent, but when

fires are in use the vent is opened as required. The upward movement of warm

air through the vent allows cold air to enter from below through the door passage.

Through this method the rate of change of air and the temperatures of the room

are controlled.

        The interior of a snowhouse is sufficiently illuminated to permit the carry–

ing out of routine tasks during daytime hours by daylight passing through the

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EA-I. Roberts: Housing

translucent walls. The full moon in a clear sky also gives enough light inside

the house for dressing and even for cooking. During periods of darkness, the

inside of the house can be illuminated by one ordinary candle, for the light is

reflected from the many crystalline surfaces of the snow dome, diffusing uniformly.

        The principal advantages of the snowhouse are that the transportation of

building material or tent is not required, no additional equipment is needed for

construction, four men can build [ ?] a comfortable camp big enough for six in a

little more than an hour, any adaptable man can be taught snowhouse-building in

one day, a minimum of heating is required to maintain a livable temperature,

clothes stay dry, and the dwelling is practically soundproof to such noises as

men shouting or dogs barking, permitting more restful sleep.

        Though the dome snowhouse was probably an Eskimo invention, it was never

universally used by them. It seems likely that, before the coming of Europeans,

more than half the Eskimos had never heard of a dome snowhouse, or had learned of

it only by remote hearsay. Possibly less than twenty per cent of them had lived

in such houses, and then only during periods of intense cold. Perhaps another

ten per cent knew how to build snowhouses, but used them only in emergency.

Geographically, the dome d snowhouse was formerly unknown, unless by hearsay, to ✓

Eskimos in northeastern Siberia, in all of Alaska, and in all of Greenland except

the extreme northwest corner, north of Melville Bay. Nowadays all Eskimos know

of the snowhouse through reading, photographs, and movies. The best snowhouses

are built in the area between King William Island and Coronation Gulf, in the

Canadian archipelago , and on the mainland. ✓

        We cannot, therefore, expect that Eskimos in every area will be able to

009      |      Vol_IIA-0424                                                                                                                  
EA-I. Roberts: Housing

construct proper snowhouses. Accordingly, travelers and intending northern

residents should learn the art of constructing this type of temporary housing

themselves. In Sweden, since 1933, dome-shaped snowhouses have been successfully

used by skiers who tour the mountains, and they were early introduced to the

Swedish army; since about 1940, the construction of snowhouses has been taught

the armed forces of most countries that engage in exercises in polar and subpolar

regions.

        Tents have long served as dependable shelters, and both fabric and skin tents

have been widely used in the Arctic. While the warmth of a tent, like clothing,

depends on air spaces, it does not seem practical with fabric tents to have these

air spaces within the fabric itself. The desired insulation quality is therefore

secured by the use of lightweight windproofed double tents. Skin tents derive

their warmth largely from the air spaces between the hairs, and, in the case of

caribouskin tents, additional warmth is provided through the hairs themselves,

these being hollow and filled with air. Under extreme cold conditions, double–

layer skin tents are used and so erected as to allow about a one-inch layer of

air between the skins. This is accomplished by placing the fur sides of the skin

toward each other.

        Dome or umbrella-shaped tents are to be preferred over peak-shaped ones such

as the tepee (tipi), ridge, or pyramidal forms. Peak-shaped tents allow the

warmth to gather at the top of the tent where occupants do not have the benefit

of the heat. However, peaked tents are greatly improved in warmth if a false

ceiling of fire resistant fabric is placed not more than seven feet above the

floor, to prevent the heat from rising to the peak. Floors for tents, if provided,

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EA-I. Roberts: Housing

should be furnished as a separate piece, or pieces, from the rest of the tent.

Floors attached to the walls of tents soon become covered with frozen condensa–

tion and snow, and cannot be cleaned easily. Conventional flap-type openings,

with ties in the front of the tent, provide a more satisfactory entrance than the

door which ties shut like the mouth of a duffle bag. The latter works only when

the material is either not frozen or else frozen and dry. When moisture gets into

the entrance, at below zero temperatures, the mouth of the bag becomes increasingly

difficult to tie and finally becomes entirely inoperative.

        All tents for per s onnel should be provided with stoves, especially where ✓

driftwood is abundant on a coast or along a river, or where bushes and trees grow.

Asbestos insulation should be placed around the aperture in the overhead layers

of canvas or skin through which the stovepipe passes. This asbestos should extend

at least four inches beyond the stovepipe. For wood-burning stoves the top–

most length of stovepipe should have a medium-mesh wire screen to keep sparks

from falling on the tent and burning holes in it; or a fireproof material should

be used.

        Guy-rope fastening tabs should be reinforced. Guy ropes should be made of

nylon and should be provided with a toggle at the end of each rope. These toggles

may be buried and tamped into the snow or frozen into a trench out into the ice.

The use of deadmen is often advisable. If tent pins are used, a light weight

metal tent pin is preferred to wood or other such material, as the metal pin

may be driven into ice or moderately hard earth without damage.

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EA-I. Roberts: Housing

       

PRINCIPLES OF DESIGN OF TEMPORARY AND SEMIPERMANENT BUILDINGS

       

General

        Important factors which will influence the design of buildings are the

materials available; the temporary or permanent nature of the construction; the

time available in which to construct; the purpose for which the buildings are to

be used; and the location and orientation of the structures. The operational

requirements will, in many cases, determine the type of building that will be used,

but the fundamental principles that influence the design will apply to all build–

ings. All housing should provide adequate space, utility, heating, insulation,

ventilation, and , if required, portability. All building construction in the ✓

Arctic and Subarctic must meet certain basic - requirements peculiar to these ✓

regions. These requirements are fixed by the special climatic, geological, and

topographical conditions, such as low temperatures, high winds, drifting or

deep snow, long periods of cold, absence of direct sunlight in midwinter and of

darkness in midsummer; foundation conditions affected by permafrost and related

phenomena; and poor drainage. (See “Work Feasibility.”) As a consequence, all

polar building design and construction possess certain common factors and

characteristics.

        Foundations for buildings to be erected in permafrost or adjoining areas

should be carefully designed after considering all factors. (See “Engineering

Problems and Construction in Permafrost Regions” and “Excavations and Foundations.”)

        Surface and subsurface drainage under the buildings must be avoided entirely

or [ ?] else it must be adequate in all seasons for conveying surface and groundwater

away from the site.

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EA-I. Roberts: Housing

        Building frames must be designed and constructed to resist stresses caused

by high winds. Resistance to high wind velocity, where required, may be pro–

vided by designing for a 20 lb./sq.ft. wind load, and, in areas of extremely

high winds, roofs should be anchored by guys. Consideration should be given to:

1. Anchoring walls or structures to foundations by bolts, reinforcing
   
   steel, deadmen, cables, or cleats.
   
   
2. Tying roof trusses and rafters securely to the frame.
   
   
3. Using knee-braces to prevent the frame from leaning sideways.
   
   
4. Using diagonal sheathing for rigidity.
   
   

        Roofs must be able to withstand strong winds and heavy snow loads. Both

may occur at the same time. Roof framing should be designed for a snow load of

30 lb./sq.ft. and strengthened if partial clearing of snow is not possible.

        The outer shell of the building must be impervious to wind, rain, and snow.

High winds have a destructive effect on roof coverings, particularly on the low–

pressure leeward side. The best roofs are metal, laid from the leeward to wind–

ward side and coated with hot asphalt. Another satisfactory roof is the built-up

type, consisting of a base sheets of 30- to 90-lb. bituminous-saturated felt

nailed with large-head roofing nails spaced not more than 6 inches apart horizon–

tally and 12 inches apart vertically, followed by one or two layers of 15-lb.

bituminous-saturated felt mopped on to the base sheet with hot asphalt, over

which battens or wood strips must be nailed to hold down the covering.

        Eaves . Where there are extremely high winds, eaves should not be used.

        Insulation must be complete throughout walls, ceilings, and floors to insure

proper heat retention, and to prevent the thawing of the permafrost under the

building.

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        A ventilated air space must be provided between the building floor and the

ground, or an insulated cover must be placed on the ground, before the floor

is laid, to preserve the thermal equilibrium of the ground and prevent thawing

below the foundation base.

        Positive ventilation and circulation of air must be maintained at all times.

This may be accomplished by the proper use of windows, doors, and vents. Window

and door openings should be small and as near the ground as is possible, to

minimize the loss of heat, and aid in controlling ventilation. All ext r erior ✓

doors should open inward, as outward-opening doors may be blocked by snow, barring

egress, or blown off by high winds. Double doors or a storm vestibule must be

provided for each entrance, unless gravity control of air is used.

        Heating . All personnel, administration, and shop buildings, and many

storage buildings, require heating. Due to the cost of construction of distribu–

tion systems, and heat losses incident thereto, individual heating units are

preferred, except for large installations. In the Arctic, due to the scarcity

of wood, coal- or oil-burning stoves are used; south of the tree line, coal-,

oil-, and as well as wood-burning stoves also may also be provided. (See Mechanical-Electrical ✓

section for discussion on this subject.)

        Fire-fighting measures and fire prevention should be carefully considered

in regard to all buildings and installations.

        Clothes-drying facilities are required for all buildings housing personnel.

These may be provided near the entrance to sleeping quarters; where possible, warm

air used to dry the clothes should be exhausted from the building.

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EA-I. Roberts: Housing

       

Insulation

        By “insulation” is meant material used, in addition to ordinary building

materials, for the purpose of retarding the flow of heat through the walls,

floors, or roofs of buildings. (Insulation is also used to reduce the transmis–

sion of sound through walls, partitions, ceilings, or floors, but sound insula–

tion is not considered in this article. ) The primary purpose of thermal insula–

tion is to permit the maintenance of the desired interior temperature in an

economical manner, to keep buildings warmer in the winter by reducing heat

losses, and to keep them cooler in the summer by reducing the penetration of heat

from the outside. While maintaining the desired interior temperatures, insula–

tion is a major factor in retarding or preventing condensation and [ ?] decreasing

or eliminating drafts.

        Obviously, good insulation results in fuel economy during cold weather.

Heat losses occur in a building by conduction and by air passing through cracks,

doors, and windows. Insulation retards this flow of heat.

        Ordinary building materials have some insulating value, but are not nearly

as effective as the special insulating materials we shall discuss. For example,

1 inch of insulation board retards the flow of heat as much as 2 to 3 inches of

lumber, 15 inches of brick, 23 inches of cement plaster, or 37 inches of concrete

made of sand and gravel.

        Types of Insulation. Various substances are used as insulation material.

The substances most commonly used are vegetable or mineral products. As a general

rule, greater insulation is obtained from the lightest weight materials. Ordinar–

ily, lightness in weight is attained by entrapping tiny air cells in and between

the insulation substances. Heat travels relatively slowly through these air spaces,

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EA-I. Roberts: Housing

since air is a very poor conductor. Insulation materials are manufactured in

various forms and shapes for case in application. They fall into the following

general classifications.

        1. Flexible Insulation. This type of insulation is made of materials

manufactured into flexible blanket, quilt, or bat form, usually with a nailing

flap along each edge for fastening between ribs or studs. The materials most

commonly used for flexible insulation are: aluminum foil (see under “Reflective

Insulation”); animal hair, available as 100% pure hair or mi s x ed (felted) with ✓

other fibrous materials, such as asbestos or jute, and stitched between sheets

of kraft paper; cotton, flameproofed and backed with water-resistant paper;

eel grass, a marine growth, processed and stitched between kraft paper; glass

fibers, interlaced into a wool d -like mass and backed with water-resistant paper; ✓

mineral wool, felted from rock wool fibers and encased in water-resistant paper;

rock wool, blown from molten rock or molten furnace slag and encased in kraft

paper; wool fibers, manufactured into cre e p ed individual plies which are stitched ✓

together, treated for fireproofing, and encased in water-resistant paper, or

asphalt-treated and flameproofed.

        2. Loose Fill or Blow-on Insulation. This type of insulation is made in

loose form. Installation is accomplished by filling the spaces between ribs or

framing members or by blowing it onto the inner surface of the outer covering

and on structural members. The most commonly used materials for loose or fill

type insulation are: cellulose fibers, mixed with adhesives when blown on;

cork, granulated or in powder form; redwood bark, ground into fleecy fibers;

rock wool, granulated or in loose form for either fill or blow-on; vermiculite,

mica ore, highly expanded by heat; wood pulp, processed to resist fire, moisture,

and vermin.

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        This type of insulation is not recommended for use in walls where the outer

or cold wall surface is more resistant to the passage of moisture vapor than the

inner or warm wall surface of the building. This insulation is pri m n cipally used ✓

on horizontal surfaces, as above ceilings and for filling wall cavities where

access is a problem.

        3. Rigid Insulation. Materials are manufactured into rigid shapes of

varying thicknesses and marketed as corkboard, insulating building board, insulat–

ing lath, insulation plank, insulation sheathing, insulation tile, insulation

plaster or concrete, and roof insulation. The materials most commonly used are:

cane fibers, waterproofed and felted together; cork, compressed under heat; glass

fibers, compressed under heat and parcels coated with a waterproofing compound;

v V ermiculite, mica ore highly expanded by heat and mixed with plaster or cement; ✓

wood fibers, felted together and pressed into solid form, usually treated for fire,

moisture, and vermin resistance.

        Rigid insulation gives good results when used in temporary and prefabricated

building, as discussed in this article. It insulate d s the inner flanges of the ribs ✓

or studs, and, since it is rigid, generally serves as an interior lining as well

as insulation.

        4. Reflective Insulation. This type of insulation is distinguished from

the other types in that its effectiveness is based on its ability to reflect

radiant heat waves. Reflective insulation, therefore, should be installed with

the reflective surface exposed to an air space. Reflective insulation is made

into thin sheet or foil form and generally applied between the structural ribs or

studs and rafters. Materials most commonly used for reflective insulation are:

aluminum foil (thin sheets) or foil backed with a kraft paper; foil on one or

both sides of kraft paper laminated with asphaltum; foil separated by air cells

which are formed by crimped paper; foil laminated to [ gyp ?] gypsum wallboard,

017      |      Vol_IIA-0432                                                                                                                  
EA-I. Roberts: Housing

lath, or sheathing; steel (thin sheets) coated with a lead-tin alloy; paper,

laminated with asphaltum, reinforced with cords or fibers, and coated with

aluminum paint.

        This type of insulation generally provides a vapor barrier in addition to

its insulation qualities. Dust settling on the reflective surfaces reduces the

insulation values. It has been found that this type of insulation is most

effective when installed horizontally and when the flow of heat through the

insulation is downward. Therefore, this type of insulation is most effective

when used to keep out summer heat or if used to insulate the floor in winter.

        Insulation Values . The heat conductivity of a material is a measure of

its insulating value; the lower the conductivity the more effective (see Table I).

Thermal conductivity, k , is the amount of heat in B.t.u. which will flow in one

hour through a layer of material one [ ?] square foot in area, where the

temperature difference between the surfaces of the layer is 1°F. per foot of

thickness. Thus the insulating value of a layer of material depends upon the

thickness of the layer as well as the k value of the material. In general, the

various types and makes of insulation are rated by their ability to resist the

flow of heat. A resistivity value, r , has been established for the heat resis–

tance offered by a unit area and unit thickness of each type of insulation material.

This is equal to the unit thickness of a layer of material divided by the k

value of the material. The insulating ability of one material may be compared with

the insulating ability of other insulating materials by comparing their resis–

tivity values. The larger the r value, the greater the insulating ability.

        When making such comparisons it must be remembered that only the insulating

materials themselves are being compared and no consideration is being given to

the effectiveness of the entire installation. After application, the r value

018      |      Vol_IIA-0433                                                                                                                  
EA-I. Roberts: Housing

Table I. Thermal Conductivities and Thermal Resistivities of Building Materials.

Materials	Weight, lb./cu.ft.	Conductivity, k	Resistivity, r	Insulating rating
Flexible insulation
Animal hair (felt)	12.0	0.26	3.84	Excellent
Cotton bats	0.875	0.24	4.17	Excellent
Eel grass in paper	3.40	0.25	4.00	Excellent
Glass wool bats	1.50	0.27	3.70	Excellent
Jute fiber bats	6.70	0.25	4.00	Excellent
Kapok bats	1.00	0.24	4.17	Excellent
Kimsul bats	1.50	0.27	3.70	Excellent
Mineral (rock wool)	10.00	0.27	3.70	Excellent
Peat moss compressed	11.00	0.26	3.84	Excellent
Wood fiber bats	3.62	0.25	4.00	Excellent
Loose insulation
Ceiba fibers	1.90	0.23	4.35	Excellent
Cork granulated	8.10	0.31	3.22	Excellent
Redwood bark	3.00	0.31	3.22	Excellent
Rock wool	10.00	0.27	3.70	Excellent
Sawdust (various)	12.00	0.41	2.44	Excellent
Shavings (various)	8.80	0.41	2.44	Excellent
Vermiculite	6.20	0.32	3.12	Excellent
Rigid insulation
Asbestos fibers	48.30	0.29	3.45	Excellent
Cane fibers	13.50	0.33	3.03	Excellent
Cork, compressed asphalt binder	14.50	0.32	3.12	Excellent
Corn stalk fibers	15.00	0.33	3.03	Excellent
Glass fibers	-	0.40	2.50	Excellent
Wood fibers:
Exploded	17.90	0.32	3.12	Excellent
Hard W w ood	15.20	0.32	3.12	Excellent
Licorice R r oot	16.10	0.34	2.94	Excellent
Various	15.00	0.33	3.03	Excellent
Reflective insulation
Foil with air space with heat flow up:
1 air space	-	0.32	3.13	Excellent
2 air spaces	-	0.27	3.70	Excellent
3 air spaces	-	0.17	5.88	Excellent
Foil with air space with heat flow down:
2 air spaces	-	0.10	10.00	Excellent
3 air spaces	-	0.07	14.29	Excellent

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Table I. Thermal Conductivities and Thermal Resistivities of Building Materials.

Materials	Weight, lb./cu.ft.	Conductivity, k	Resistivity, r	Insulating rating
Other building materials
Asbestos millboard	60.5	0.84	1.19	Good
Asphalt roofing	55.0	0.70	1.43	Good
Brick, masonry (wet)	120.0 ±	5.00	0.20	Fair
Cement mortar	100.0	12.00	0.08	Poor
Concrete, typical	142.0	12.60	0.08	Poor
Concrete, cinder	97.0	4.90	0.22	Fair
Concrete (1:2:4)	143.0	9.46	0.11	Poor
Concrete, expanded vermiculite aggregate	20.0	0.68	1.47	Good
Concrete pumice aggregate (mined in California)	65.0	2.42	0.41	Good
Gravel, loose dry	106.0	7.50	0.13	Fair
Ice, fresh-water	57.5	15.10	0.07	Poor
Limestone	124.0	6.45	0.15	Fair
Snow, compacted 15.0 − + 0	50.0	1.48	0.67	Good
Soil, dry-packed	94.0	2.60	0.38	Good
Woods (across grain):
Balsa	20.0	0.58	1.72	Excellent
Douglas fir	34.0	0.67	1.49	Good
Hemlock	22.0	0.73	1.37	Good
Oak	38.0	1.02	0.98	Good
White pine	31.2	0.78	1.28	Good
Yellow pine (short leaf)	36.0	0.91	1.10	Good
Yellow pine (long leaf)	40.0	0.86	1.16	Good

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EA-I. Roberts: Housing

of the insulating material is but one factor in the over-all effectiveness of

the installation. The number of air spaces created, the resistances of the

various building materials themselves, and the surfaces exposed, all contribute

to the over-all effectiveness of the insulation provided for the building.

       

Condensation

        By condensation is meant the moisture which is deposited by the air on the

inside walls or roof of a building. It does not necessarily occur at all times

in buildings but is the more rapid the larger the temperature differences,

especially during periods of relatively high humidity. Air is a mixture of gases

such as nitrogen, oxygen, etc., and water vapor, all of them normally invisible.

The gases occur in comparatively fixed relationships but the amount of water

vapor in air varies greatly. This variation depends on the source of water vapor

and upon the temperature of the air. Air at higher temperatures can carry more

water than at lower temperatures.

        Condensation is caused when air, carrying water vapor, is cooled to a

temperature at which it no longer can carry all of the water which it previously

contained. This is the dew-point temperature. When the dew point is reached,

the excess water in the air changes from water vapor to visible liquid or solid

water. This transition is called condensation.

        Table II gives the maximum weight of water which one pound of air at various

temperatures can absorb and carry.

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Table II.

Temperat o u re, °F.	Carrying capacity of 1 lb, of air in grains* of water
−50	0.29
−40	0.55
−30	1.02
−20	1.84
−10	3.22
0	5.51
10	9.20
20	15.06
30	24.18
40	36.49
50	53.61
60	77.56
70	110.74
80	156.31
90	218.3
100	302.3
110	416.1
120	570.4
130	781.2
140	1,073.8
150	1,487.5 (0.21 lb.)

* 7,000 grains equal 1 lb.

        The moisture-carrying capacities shown are for the same air pressure so as to run in this para with preceding page

give comparative figures. Notice that a pound of air can absorb and carry

110.74 grains of water at 70°F. The same pound of air can absorb less than numbers changed in this paragraph to conform with numbers in table.

half of this amount at 50°, less than one-fourth at 30°, and less than one-tenth

(9.20 grains) at 10°F.

        The table gives the maximum amount of moisture that air can carry at the

temperature shown. When carrying this maximum , the air is called saturated and

has a relative humidity of 100%. Usually air is not fully sat i u rated with water

vapor and therefore seldom has a 100% relative humidity. The ratio of the amount

of water vapor in the air to the amount which it can hold when saturated is called

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EA-I. Roberts: Housing

the relative humidity. If the relative humidity is 50%, the air contains one–

half of the water which it can carry when fully saturated at the same temperature.

Outside air brought into a building and heated will have a drying effect, even

though rain is falling and the air outside is practically saturated. For when

saturated air is warmed, it is no longer saturated but becomes capable of carry–

ing more moisture.

        At this point it is perhaps well to consider the sources of this water vapor.

Water may exist in three forms. We usually think of it in liquid form. It also

exists in solid form, which is called ice, or it may exist in a gaseous form,

which is called water vapor or steam. Steam is invisible; the white cloud

commonly called “steam” actually is condensed steam and consists of visible

particles of water.

        With no water vapor in the air, condensation could not take place. One hun–

dred per cent dry air is difficult to obtain even in a laboratory and such air is

not desirable from the human living standpoint. All outside air, even that in

a desert, carries a certain amount of water vapor; the air of warm deserts is

seldom as deficient in water as that of a fifty-below-zero day of the northern

winter. During a rainstorm, the outside air is practically saturated. The amount

of moisture in outside air, therefore, varies greatly depending on the surround–

ings, the temperature, and the atmospheric conditions.

        In addition to the moisture which is in the outside air, water vapor may be

liberated inside of buildings from the bodies of the occupants or through other uses

of the building. Because water vapor is low-pressure steam, any operation such as

cooking, washing, bathing, or drying clothes adds to the amount of water vapor in

a building. Potted plants give off moisture. Animals and humans also give off a

023      |      Vol_IIA-0438                                                                                                                  
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certain amount of moisture, depending upon how fast they use their energy. A man

at rest liberates 0.2 lb. of water per hour while a man at normal work liberates

0.6 lb. per hour. A man walking 4 miles per hour liberates 0.9 lb. per hour.

        In addition to the moisture in outside air and moisture from building uses,

water vapor is also produced by damp surroundings, wet floors, etc. If condensa–

tion problems persist within any building, it is advisable first to determine if

the sources of water vapor can be controlled. If these are not subject to regula–

tion, it becomes necessary to control the water vapor itself.

        Methods of Condensation Control . Condensation may be controlled or entirely prevented in buildings by main–

taining the inner surfaces at or above dew-point temperatures, or by reducing the

relative humidity. These two objectives are attained by various methods.

        1. Insulation. From a review of the moisture-carrying capacities of air

at various temperatures, it is obvious that if interior air does not become

cooled when it comes in contact with the walls or roof of a building, it will not

lose its moisture-carrying capacity, so condensation will not occur. This method

of control requires insulation to keep the inner surfaces of the walls and roof

near room temperature. In such installations, the moist [ ?] inte r ior air comes in

contact with the inner surfaces of the insulation and not with things like cold

metal in walls or roof. Condensation is prevented because the interior surfaces

of the insulation are near room temperature. Care must be taken to install a

vapor barrier on the warm side of the insulation, as described below, in order to

retard the filtering of water vapor through the insulation itself.

        2. Ventilation. It is obvious from the above that condensation will not

occur if there is no difference in temperature between the inside and the outside

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of a building. This sameness of temperature inside and outside is most easily

maintained by ventilation, merely by keeping doors, windows, louvers, or venti–

lators open. However, in certain instances, forced or mechanical ventilation

may be required. It is obvious that this type of control is a summer method; due

to the low temperatures involved in an arctic winter this method is not satis–

factory at that season if warm buildings are required.

        3. Humidity Regulation. Condensation can be controlled by reducing the

amount of water vapor in the air (relative humidity), since condensation will

not occur if the amount of water vapor is kept within the air’s ability to carry

the vapor at the lowest air temperatures. Certain uses of such buildings as

kitchens, laundries, and bathrooms create a great amount of water vapor as a by–

product of operation. In such installations, the increasing amount of water vapor

has a tendency to saturate the air and finally to condense, if not removed. Fre–

quent changes of interior air are [ ?] recommended to prevent the accumulation of

these vapors. It is desirable, in certain installations, to remove the excess

vapor at its source by installing special exhaust ducts. However, the excess can

be removed in most instances by opening windows, ventilators, louvers, or by the

use of exhaust fans. By such operation, the cooler outside air enters the build–

ing; when warmed, it is able to absorb additional moisture. As it leaves the build–

ing, in its warmed condition, it carries out more water vapor than was brought

in by the cooler incoming air. In the Subarctic and Arctic, where extreme tempera–

tures of −50°F. may be expected, the relative humidity may be as high as 80 or

90%. The actual moisture content of the air at this temperature is slight. Air

with a temperature of −50°F. if taken into a building and warmed to 70°F., without

moisture being added, will have a very low relative humidity, possibly less than 5%.

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        The amount of water vapor in the interior air may also be reduced by dehydrat–

ing agents such as silica gel, etc., or by mechanical dehydration processes. De–

hydration by these methods is a relatively expensive procedure.

        4. Vapor Barrier. If the water vapor, which is in the air, is kept from

coming in contact with the cooler walls and roof, no condensation can occur.

Keeping the moisture of the interior air from the cold walls and roof is accomplished

by installing a vapor barrier such as a waterproof membrane or diaphragm between

the interior air and the walls or roof. Obviously, the vapor barrier must be

kept at a temperature above the dew point or else the water vapor will condense

on the barrier itself. It is, therefore, necessary to place the vapor barrier

on the warm side of the insulation.

        Table III lists the vapor transmission rates of the better-known materials;

the lowest transmission rates [ ?] how the most effective vapor barriers.

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Table III.

Materials	Transmission of water vapor in grains/sq.ft./hr./in. of mercury pressure difference
Double-faced aluminum foils surfaces	0.085 - 0.129
Roll roofing (smooth surface);
40# to 65# per 100 sq.ft. roll	0.129 - 0.171
Asphalt-impregnated sheathing paper:
50#/500 sq.ft. roll	0.213 - 0.770
35#/500 sq.ft. roll	0.171 - 2.060
Insulation back-up paper, treated	0.660 - 3.420
Gypsum lath with aluminum foil backing	0.085 - 0.385
Plaster and wood lath	11.000
Plaster and 3 coats lead and oil paint	3.680 - 3.850
Plaster and 3 coats flat wall paint	4.280
Plaster and 2 coats aluminum paint	1.150
Plaster and fiberboard or gypsum lath	19.700 - 20.600
Plywood, ½ in. (5-ply Douglas fir)	2.670 - 2.740
Plywood, ¼ in. (3-ply Douglas fir)	4.270 - 4.620
Plywood and 2 coats asphalt paint	0.430
Plywood and 2 coats aluminum paint	1.290
Mineral wool, 4 in., unprotected	29.100
Blanket insulation, ½ in. and 1 in., between coated papers	1.920 - 2.000
Brick masonry, 4 in	1.100

        Insulation is recommended for keeping the inner surfaces of the walls and

roof at near room temperatures. Because water vapor filters through nearly all

types of insulating material, as shown in Table III, a barrier should be placed

on the interior warm surface of the insulation material. This will keep most

of the moisture from filtering through the insulation to the colder part of

the well.

        Asphaltic lining or coating is effective as a vapor barrier. Thin sheets

of metal, well joined at seams, make excellent barriers. Many insulation materials

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are manufactured with a vapor barrier on one surface; some insulation boards

have a vapor barrier on both surfaces.

        Two coats of oil paint or varnish over a well-sized smooth surface is an

effective vapor barrier; aluminum flakes added to the paint [ ?] make it still more

effective. It must be remembered that this type of barrier is effective only

as long as it is free from cracks and checks, and that filling cracks by repaint–

ing or otherwise will renew effectiveness.

        Special vapor barriers are required in the design of buildings for the Arctic

because ordinary building materials are vapor permeable. Under extreme tempera–

ture conditions, creating wide differences of air pressures at temperatures like

−50°F. and 70°F., there is a natural tendency for the unbalanced to equalize.

The warmer interior, having the higher vapor pressure, loses moisture at a ratio

in accordance with the vapor permeability factors of the wall structure material.

To eliminate this condition a barrier consisting of a layer of waterproof membrane

or other highly impervious material should be installed on the warm side of the

interior, usually under a layer of wallboard or other interior wall finish.

        The vapor barrier must be kept at a temperature above dew point or else the

vapor will condense on the barrier. Care must be taken to assure that bolts,

nails, or other metal fasteners do not extend through the barrier into the outer

wall or center air space provided in the wall section or roof. The absence of an

effective vapor seal will allow moisture to condense and freeze within walls or

under roofs. Alternate freezing and thawing under such conditions will cause

buildings to deteriorate rapidly.

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Ventilation

        Ventilat ing ion needs depend on the type of housing and the use to which the ✓

housing is put. Wherever men live and operate within doors, the gaseous products

of respiration and combustion should be removed as quickly as possible. This may

be accomplished either by natural or by mechanical methods of displacement of

the vitiated air and its replacement by fresh air.

        Natural Ventilation . The two natural forces for moving air into, through,

or out of buildings are the wind and the gravity forces. The incoming air mixes

with and dilutes the foul air to a point suitable for healthful respiration.

        In considering wind forces, the velocity and direction of wind and the near–

ness of hills and other obstructions must be considered. However, the ventilation

of most of the housing discussed in this article is induced mainly by gravity —

that is, by the thermal head produced by the difference between the density of

the column of air in the outlets and in the outside atmosphere. The size,

location, arrangement, and control of the inlet and outlet openings of a build–

ing should therefore be such that these two forces act together to provide

positive ventilation rather than in opposition. The most effective gravity

ventilation is obtained by the use of roof ventilators. The largest flow per

unit area of openings is obtained when the outlets and inlets are equal, but in

the Arctic that condition is not desirable because too much loss of heat would

result.

        In mechanical ventilation the movement of air is positively maintained by

means of various types of fans, driven by an engine or by an electric motor.

This type of ventilation finds wide use in the Arctic for garages, shops, hangars,

mess halls, kitche sn ns , theaters, and special buildings, requiring rapid air change. ✓

029      |      Vol_IIA-0444                                                                                                                  
EA I. Roberts: Housing

        It must be remembered that ventilation imposes a load on the heating plant

of a building. When the heated air is replaced with air from the outside, the

incoming air must be heated. In the Arctic this is a major factor in the total

heating load. For example, under extreme arctic winter conditions for a building

20 ft. wide, 48 ft. long, and 8 ft. high, one complete air change per hour in–

creases the heating load something like 25%, so that four complete changes would

mean a 100% increase. It is, therefore, necessary to hold ventilation to the

minimum consistent with physiological requirements. The following absolute

minimum ventilation requirements should be considered.

        Garages: supply or exhaust one cubic foot per minute per square foot of

floor space.

        Shops: same as garages, except that paint shops should be provided with

supply and exhaust fans for year-round operation, and should be capable of

effecting 20 changes of air per hour.

        Hangars: 1 change of air per hour supplied usually by infiltration.

        Kitchens: 10 air changes per hour.

        Mess Halls: 2 air changes per hour.

        Residences: 1 air change per hour.

        Theaters: 10 c.f.m. per person fresh air introduced. Chapels and auditoriums

same as theaters.

        Barracks: 1 air change per hour or 10 c.f.m. per person if men are crowded.

        Toilets: 10 changes per hour.

        Laundries: 3 0 changes per hour.

        Hospitals: 12 changes per hour.

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TEMPORARY HOUSING

        The preceding discussion has dealt with the general principles of design of

housing for arctic and subarctic regions with important considerations regarding

insulation, condensation, and ventilation. It must always be remembered that

restrictions imposed on the weight and the cubage of construction material by

transportation facilities act as a checkre in on elaborate design. Even more

critical is that building in the Arctic is accomplished in an area in which snow,

earth, and a meager supply of wood are usually the only local materials available,

though rock materials do abound in some places. Simplicity of design, therefore,

is the factor that influences all buildings and particularly those that are to

be temporary.

        Temporary buildings can be constructed from snow and from other more stable

[ ?] local materials. Such buildings are the domed snowhouse, and the house of

earth and wood. These two dwellings, with skin tents, are the basic types of

housing used by most of the Eskimos since ancient times. The domed snowhouse

and skin tents have been described under “Emergency Housing.”

        The earth and wood house may be built with driftwood along the coast, and

along rivers, or with the use of felled trees in the northern forest. The size of

the house will be determined largely by the availability of wood; the Eskimos

usually have a long alleyway and one proper room from nine to sixteen feet square,

with a seven- or eight-foot ceiling at center. Where two rooms are used, the first

is usually the smaller and considered to be a storage room; the inner or larger

room is the house proper.

        The site for the house should be on a rise, not in the lee of a hill, with

Fig. 5 4 drainage away from the building (see Fig. 3 4 ). Posts are erected forming the ✓

030a      |      Vol_IIA-0446                                                                                                                  

031      |      Vol_IIA-0447                                                                                                                  
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corners of the house. In selecting the posts, ones with crotches should be used.

Posts are set in place by thawing the ground through alternately building a fire

over the spot and then excavating. If equipment is available, holes may be sunk

by using a steam point, the steam supplied by a hose from a low-pressure boiler.

With either method, when the hole reaches the desired depth, the post is set;

thawed earth is packed around and tamped. It is sometimes necessary to brace

each post until it freezes in position. Logs are now placed between the crotches,

forming the plate or top of the walls. Sticks and split logs are set off the

vertical between the ground and the plate, leaning slightly toward the center

of the building and forming vertical sheathing. This is necessary, as the wall

framework leans slightly inward to support the earth that is later to be heaped

against it.

        Four posts are now erected in the center of each room, forming a three–

to five-foot square. These posts should be longer than the posts used in the

walls, to provide a slope to the roof of fifteen to thirty degrees. The tops of

the posts are connected by logs which become the ridge members. The square

formed by the ridged logs becomes a skylight. A particularly strong log, the

hip rafter, is placed between the corner of the skylight frame and each corner

post. Other rafters are placed between the plate and the ridge members or the

hip rafters. Roof sheathing should be placed over the rafters to support the

earth covering. Small sticks, tall grass, moss, or fluffy vegetation may be

used for this purpose as only a two-, three- or four-inch layer of dirt is re–

quired on the roof.

        An outside entrance or doorway is then excavated from a point about ten

feet away from the wall of the house. This trench should slope gradually to a

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point just outside the wall of the house, and then run level into the house.

The walls and roof of the trench may be of light material. The doorway to this

entrance need not be airtight, for it is not intended that this alleyway be heated.

        Broken sod and loose earth are then piled against the framework of the

building, sloping from about four to five feet at the bottom to about twelve

to eighteen inches at the cave. The rafters are then covered with earth to a

thickness of about six inches at the cave to about two or three inches at the

edge of the skylight. The floor of the house may be earth, split logs, or brush

matting.

        In former times, the skylight had a cover made by [ ?] sewing together strips

of seal, walrus, or bear intestines; nowadays a thin oiled cloth is used. During

the winter, an ice pane may be used for a subsidiary window, placed low down in

the wall, usually facing south. This windowpane may be cut from a fresh-water

stream or pond. Sea ice may be used, but then the pane will be milky instead

of clear and will not admit as much light.

        The vent is installed to one side of the skylight. This pipe may be made

of wood or a hollow log and should be from five to ten inches in width, depend–

ing on the rate of change of air required. The control of temperature and venti–

lation can then be maintained by the gravity method by stuffing a wad into the

vent, thus varying the size of the opening, and controlling the rate of change

of the air that wells up through the trap door from the alleyway, which is never

closed, unless barred to keep dogs out.

        For heating the house a small stove is nowadays used; formerly the heating

was by the same whale or seal oil lamps which lighted the house. When using a

stove, a pipe must be installed through the roof. If the house is in a forest,

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where wood is plentiful, an open fireplace, a hearth of stones, may be built in

the center of the house. The stones absorb heat and aid in controlling the

temperature of the house. When the open fireplace is in use it is necessary to

remove the skylight. After cooking, the fire is quickly removed and the skylight

replaced, whereupon the stones become the active heating agency, giving out

warmth for several hours.

        Various types of earth houses may be constructed; the larger bones of whales

and other large sea mammals, especially ribs, shoulder blades, and (whale) jaw–

bones, may be used in place [ ?] of wood. In that case, however, the size of the

house will be much smaller than just described.

        Sod houses, American prairie style, with skin or brush roofs, and caves ex–

cavated into hills, may provide adequate shelter when no other materials are

available.

        Wanigans . For units such as reconnaissance and initial construction crews,

and for over-ice freighting parties, operating away [ ?] from camps with heavy

equipment such as tractors, wanigans may be used to advantage. These mobile

structures possess great versatility, can be built of frame or prefabricated

materials, and lend themselves to use in isolated areas. Wanigans serve as

galleys or cook shacks, mobile hospitals, repair shops, water and fuel carriers,

sleeping quarters, offices, and warming shelters for personnel engaged in work

out of doors in cold weather.

        A wanigan is a rugged structure, usually about eight feet by twenty feet,

which may be mounted on a sled or “go-devil” and towed by a tractor or other

prime mover. The walls, roof, and floor are insulated, with windows and doors

provided for ventilation and egress. Each unit is heated by a stove. The heavy

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braced construction of the wanigan enables it to withstand damage from twisting,

vibration, and impact while being towed over a rough terrain.

        Jamesway-Portabilt Huts . This type of portable insulated temporary building

has proved to be one of the most flexible and satisfactory prefabricated units

developed to date. The Jamesway hut is versatile in that it is light in weight

and, therefore, can easily be transported by air, sea, and over ice or land.

It can be erected or dismantled quickly by inexperienced personnel and provides

a comfortable building which can be used for temporary housing of personnel,

administration, or storage. These buildings were originally built for the U.S.

Army Signal Corps, during World War II, by the James Manufacturing Company of

S Fort Atkinson, Wisconsin (see Fig. 4). They are now known as the “Portabilt

Shelters” and are manufactured by Portabilt Structures, Inc., of Fort Atkinson,

Wisconsin.

        These standard units are sixteen or twenty-four feet wide and may be erected

in any length that is a multiple of eight feet. The framework consists of a

series of laminated wood (glued with urea-formaldehyde resin) or steel arches,

which when erected are attached to the floor panels. Each floor panel consists

of an exterior plywood surface fastened to and supported by a braced plywood

framework. The underside of the panel is faced with a blanket of fireproofed

rock wool or fiber-glass insulation, one and one-half inches thick, protected

by a vinylite resin impregnated, surface-coated fabric. In extreme cold a double

floor is required. The outside layer or roof blanket coverings are made in

eight-foot widths and of the correct length to extend in a continuous covering

over the full arch from base at one side of the building to base at the opposite

side. The roof blankets and end enclosure blankets are reinforced to withstand

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severe wind and snow-load stresses and consist of an inner and outer surface of

vinylite resin impregnated and surface-coated heavy fabric, which encloses a

one and one-half inch layer of fireproofed rock wool or fibre-glass insulation.

The protective coating windproofs and waterproofs the fabric and does not become

brittle or sticky under extreme cold. These coatings are furnished in any color

desired. Vestibules and storm doors are available and should be included if the

buildings are to be occupied for a prolonged period. Gasoline or oil-burning

heaters are provided with each building.

        The site selected for the erection of a Jamesway hut should be one where

natural drainage is away from the building. A level gravel mat should be provided

and well tamped before the end wall base sections and the floor rafters are set

in place. Hardwood or steel stakes are required to anchor the building base

sections and guy ropes. A Jamesway hut may also be used as a wanigan by mounting

it on a sled, “go-devil,” or on timber or pipe runners.

       

SEMIPERMANENT HOUSING

       

Prefabricated Housing

        Prefabricated housing or portable buildings of a semipermanent nature lend

themselves to future use and large-scale development for the Arctic. South of this

vast polar area, and within reach by air and water-shipping facilities, lie broad

virgin forests, where the demand for prefabricated housing will inevitably foster

the growth of a prefabricated building industry.

        The use of prefabricated houses in the polar areas is not new. The first oc–

casion we find on which an arctic expedition equipped itself with a prefabricated

building was also the first modern attempt at colonization in North America. In

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1578 Sir Martin Frobisher was directed by Queen Elizabeth to undertake a “Thyrd

Viage to the Northwest to fitch 2000 Toones of Oore and to vittal and keepe there

100 Men 18 Monethes.” Writing a “True Discourse” about this abortive excursion

after a gold ore which turned out to be iron pyrites, George Best records that

distributed among the fifteen ships “there was a strong forte or house of timber,

artificially framed, & cunningly deuised by a notable learned man here at

home, in ships to be carried thither, whereby those men that were apointed there

to winter & make their abode ye whole years, might aswel be defended from the

danger of ye falling snow and colde ayre, as also be fortified from the force or

offence of those Countrie people, which perhaps otherwise with too greate

companyes & multitudes might oppresse them.”

        Frobisher, gathering his fleet in the proper place, started the miners to

work. “The ninth of August, the Generall with his Captaynes of his counsell

assembled togither, beganne to consider and take order for the erecting vp of

the house or forte, for them that were to inhabite there the whole years, and

that presently the Masons and Carpentees might go in hande therewith. First

therefore they perused the Bils of ladyng, what euery man receiued into his

shippe, and founde that there was arriued only the eastside, and the South–

side of ye house, and yet not that perfecte and intier, for many peeces thereof

were vsed for fenders in many shippes, and so broken in peeces, whyles they

were distressed in the Ise.”

        The craftsmen were called in and asked how long it would take to build a

smaller house for Captain Fenton and only sixty men. They answered eight or nine

weeks. “Wherefore it was fully agreed vppon, and resolued by the General and

his counsell, that no habitation shoulde be there this years.” What remained of

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this building was then buried beneath the gravel on Countess of Warwick Island,

where Hall found it two hundred and eighty-three years later. So, unable to

winter, Frobisher sailed his laden ships home.

        Whether discouraged by the fate of Frobisher’s crucial house, or unwilling

to allow that Cathay could not be reached in one season, northwest passage

expeditions for the next three centuries did not supply themselves with pre–

fabricated buildings. True, it is written that Hans Egede brought a portable

house with him to Greenland in 1721, but he came to stay as a missionary. Nearly

every other expedition relied upon converting its ship into winter quarters,

or , like Barents, else, in an emergency , built a house from the boards of the ship . or from driftwood found on shore.

The Russian hunters, who exploited Svalbard after their abandonment by the

whalers, lived in European-style sod huts. As Greenland was Christianized and

slowly developed for trade with the Eskimos, whole villages were erected with

mater ai ia ls, partially prefabricated, sent from Denmark. ✓

        By the latter part of the 19th century the attainment of the North Pole

became a sporting venture involving a good deal of national pride. In 1877

Captain Henry W. Ho w gate, U.S. Army, proposed that the United States establish ✓

a polar colony in northern Ellesmere Island which might serve as a base for

a dash to the North. Lacking support, his project failed; but not before a

prefabricated house had been sent as far as Godhavn, Greenland. There it was

picked up in 1881 by Greely’s Lady Franklin Bay Expedition, which took it north

to Discovery Harbor, Ellesmere Island, where it was erected as “Fort Conger.”

        The Fort Conger building was 60 by 17 feet and divided into three rooms, a

large living quarters for the enlisted men, a smaller one for the officers, and

a kitchen. Double-walled by half-inch planks, a one foot nonconductive air space

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was left between. Both inside and outside walls were covered by the heaviest

black tarpaper, the first by tongue-and-groove paneling, the latter by secure

battening. The peaked roof was treated in the same manner as the outside wall,

but beneath it was a ceiling of more tongue-and-groove boarding. The black tar–

paper served to absorb solar heat, while the air space reduced heat conductivity,

and, outside, brumal snowbanks effectively minimized heat loss through radiation.

A bathroom, replete with tub, abutted against the chimney, insuring comfort at

all times. Within two weeks the building was ready for occupancy.

        One of the best prefabricated houses used by a late 19th century arctic

wintering party belonged to the Frederick Jackson Expedition to Franz Josef

Land, 1894-1897. A Russian log hut, it had been purchased by Jackson in Archangel

where, to check it, he had ordered it completely set up before taking it north.

Every piece was carefully numbered, and a Russian carpenter was brought along

to erect it.

        The central living space of Jackson’s house was only about 13 by 12 feet,

and was surrounded by pony stables and two small bedrooms. The exterior of the

building was thoroughly calked with oakum, and the interior wall covered with

green felt. On the floor lay sheets of heavy brown paper overlaid by patterned

felt, and the seven-foot ceiling was covered by gray felt. The windows were all

double-glazed. Ventilated by two apertures, one consisting of a series of per–

forations low in the south wall and the other a 4 -1/2 ½ -inch hole in the roof, ✓

each easily plugged, it was heated by a large Russian oven and a small slow–

combustion stove. In one corner stood a snow-melting tank, heated by the warmth

of the main room.

        The chief drawback of the building was that a site was chosen for it beneath

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a cliff where dwelt the god, Aeolus, and the continual winds and strong gusts

frequently got a fingerhold on the roof planking, flinging it far and wide.

By no means cast down, Jackson said of “Elmwood:” “Ours is without doubt the

most suitable, best, and most comfortable house ever put up in this latitude.”

To the retreating Nansen, who sought refuge there, it seemed like high civilization.

        If “Elmwood” was the most successful of the early prefabricated arctic

quarters, then certainly, in an esthetic sense at least, Peary’s famous “Red - +Cliff House”

cliffe” house was the least so. With tarpaper crudely fastened helter-skelter

on the exterior and weighted down by rocks, surrounded by a low and broken turf

wall, and with various pipes and cans jutting out from unexpected places, it

resembled nothing so much as a kitchen midden. Yet it was shelled by heavy

cardboard and lined with red blanketing which created an intershell air space.

Warm and comfortable, it took but six days to erect.

        These early prefabricated buildings for the Arctic left a great deal to be

desired in the way of efficiency. Often erected in permafrost areas, their

internal heat caused the ground to thaw beneath them, resulting in the tilting

or sinking of the structure. Insulation was inadequate, and though the houses

were acclaimed as cozy or warm, excessive amounts of fuel were required to main–

tain comfortable temperatures. None of the buildings were fireproof, an un–

warranted risk in regions where replacement was impossible.

        Perhaps the most significant point, however, is that the prefabrication of

these buildings was only partial at best. More often than not it consisted of

supplying merely the required materials, cut and numbered, with erection instruc–

tions. Here the 20th century was to see progress. The first mass production of

prefabricated buildings was carried out by a German firm, Christophe and Unmack,

which shortly after the Franco-Prussian War manufactured dormitories, cottages,

and barracks, sending them to many parts of the world.

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Modern Prefabricated Buildings

        Today there are many prefabricated structures being utilized in the

Arctic to provide housing. Such buildings are in use mainly because they

are easily transported, quickly erected with a minimum of skilled labor,

require a minimum of shipping space, and, while not supplying the o c omplete ✓

answer to the housing problem, have proved worthy under arctic conditions.

Any of these buildings can be improved or modified, depending on the need and

ingenuity of the user. The principal types are the Quonset Hut, the Stressed

Skin Plywood Building, and the Military Arctic Hut.

        ✓ Quonset Hut . This building (see Fig. 5), which saw universal service with

the U.S. Armed Forces during World War II, was developed by the U.S. Navy and

resulted from the improvement of the British World War I M N issen hut. These ✓

buildings are now manufactured by the Stran-Steel Division of the F g reat Lakes ✓

Steel Corporation, Detroit, Michigan. The huts are primarily a metal structure

with an arch-rib framework supporting corrugated steel sheet covering material.

        The basic arctic unit is a building twenty by forty-eight fest, interior

size, with a four-foot vestibule extention on each end of the building. Fixed

wood end walls were provided, framed with steel studs. The end walls now are

built entirely of steel. An additional end wall is required for each end to

form the vestibule. The units are provided with inner insulated walls and the

resistance value of these walls may be controlled to meet the design dictated

by the climatic factors.

        The over-all resistivity, r , for a Quonset building may vary from 4.82 to greater than 9.70, depending on the insulating and building materials selected

to meet the design requirements. A typical section of Quonset buildings in use

at Point Barrow, and elsewhere in northern Alaska, provides a total resistivity

040a      |      Vol_IIA-0457                                                                                                                  

041      |      Vol_IIA-0458                                                                                                                  
EA-I. Roberts: Housing

✓ of 9.63 and a total conductive factor of 0.103 (see Fig. 6 5 ). The floor ✓

consists of four- by eight-foot plywood double panels with insulation in

the space between the two thicknesses of plywood. Doors, windows, interior

wall partitions, adjustable vents, and end wall louvers are furnished with

each building, as well as such miscellaneous materials as foundation anchor

bolts, screws, bolts, nuts, washers, clips, and nails. All framing members

receive one coat of rust-resisting paint.

        The Quonset hut is simple to build, requiring about one hundred man-hours

to erect the bare structure, with additional time required to provide either a

gravel mat or pile foundation and to install the insulating materials.

        Larger buildings of the arch-rib design are available for use. These buildings

are forty feet wide and one hundred feet long, and lend themselves well to use

as storage or recreation buildings as well as for shops. They are easy to

develop into two-story units for administrative or dual-use buildings. The

walls are insulated tih with kimsul and wallboard to meet the design requirement. ✓

        A building of the arch-rib type may be erected on a gravel mat, concrete, or

timber pile or sills on top of block-type construction. Concrete or wood

floors may be used and should be insulated to eliminate the transfer of heat

from the building to the foundation or soil below. (See Civil Engineering

Section for subjects related to foundations and construction.)

        Stressed Skin Plywood Buildings . Several types of these buildings are

manufactured by the Tower Company of Toronto, and have been set up on the ✓

mainland and islands of the Canadian Arctic from Aklavik to Labrador. They

are light in weight, comparatively inexpensive, and can be quickly erected

by a small crew. Such buildings are prefabricated throughout and consist

of floor, wall, and roof panels, each highly insulated, which when nailed and

screwed together form a rigid frame structure. It is desirable to set the

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building on top of a gravel bed, two or three feet in depth. The site

selected should be well drained and any vegetation should be left undisturbed.

The building panels consist of a stud frame on which exterior or marine-type

plywood layers are glued and nailed. Between the outer plywoods the panels

contain a sandwich of triple insulation of fiber glass aluminum foil, and

fiberboard to obtain the highest possible insulation against convection,

radiation, and conduction. The panels are held together by special connectors.

All outside joints are covered with felt-lined joint strips which help to

make the buildings airtight. The standard size of the panels is four feet

by eight, and they are light enough to be easily handled by two men. In

special cases, where only a small aircraft may be available to fly the building

components to the site, these panels have been made as small as two feet by

eight feet.

        The outside of the building is painted with high-grade aluminum paint which

has proved very resistant to weather action in the Arctic. Aluminum sheet

roofing covers the roof. The gable ends and corners have specially made

flashings to keep the building snowtight. All overhangs, jut-outs, or sharp

corners are avoided to prevent finger-lift action by the wind; because of their

smooth exterior, the buildings withstand storms up to 65 m.p.h. without having

to be tied down. At locations where higher wind velocity and gusts are

expected, tie rods with turn buckles are used to anchor the buildings to the

ground.

        The chimneys are either of precast, lightweight concrete, in which ground

mica is used, or galvanized pipe chimneys of the Yukon type. The triple-glazed windows ✓

cannot be opened. Above them is a built-in ventilator with a refrigerator-type

door which provides the necessary ventilation. The buildings are heated with

043      |      Vol_IIA-0460                                                                                                                  
EA-I. Roberts: Housing

oil-fired space heaters which are placed at a central point to insure

even heat distribution. The floor is covered with colored linoleum and

the walls and ceilings are painted with bright fire-resistant paint.

        For larger structures of an industrial nature, like powerhouses, garages,

and warehouses, a different variant of the floating construction method is

used. These buildings generally have no panel floor. They lose, therefore,

the principle of the rigid frame as the floor panels no longer tie the buildings

together. Wherever possible, a reinforced-concrete slab is used as a floor.

Solid bedrock with no water veins or decomposed upper layer is the best

foundation for such a slab; but sometimes a slab can be laid on a gravel

fill which carries a special insulation of celboard (a two-inch thick concrete

insulation material made out of shavings which are sprayed with concrete).

Where the slab is not practicable, the gravel bed itself is used as the floor

of the building. In this case special ballasted outriggers have to be spaced

alongside the building to prevent it from moving or being blown over by the

wind. The outriggers consist of heavy timbers and tie rods which start at the

caves and spread about five feet away from the building. At the bottom they

are connected with horizontal wooden beams to the wall panels. They are spaced

eight feet apart and are ballasted with gravel, and are similar in action to

the outriggers used on South Sea boats. During the winter these outriggers

will catch the snow; the resulting snowdrifts on each side will keep the

building stable and warm.

        Military Arctic Hut . A prefabricated hut, light enough to be air-borne,

has been designed to serve as a sixteen-man barracks, or for equipment storage,

in frigid zones, (Fig. 7). It will make possible, with a small outlay of S ✓

fuel, an interior temperature of 70°F. when outside temperatures are as low

as −65°F.

044      |      Vol_IIA-0461                                                                                                                  
EA-I. Roberts: Housing

        In recent tests, the hut was erected in one hour and forty-five minutes

by twelve Naval personnel (Seabees) using arctic mittens. Low temperatures

and the usual white-man type of arctic clothing will probably slow the

assembling operation to more than four hours. However, even under adverse

conditions, it will be more rapidly assembled than any type of hut so far

tested.

        This hut, built by the Douglas Aircraft Corporation of California, is

made up of panels consisting of a resin-impregnated paper honeycomb core

sandwiched between two 1/50-inch aluminum skins. The wall panels are 3 inches

thick, the roof and floor panels 5 inches thick. Panel edges are of a plastic

fiber glass laminate, and the shiplap joints are fastened with pins approxi–

mately 6 inches long and 7/8 inch in diameter. The pins are of plastic

reinforced with fiber glass, to prevent conduction of heat. They are held in

place by metal wedges.

        Twelve 4- by 8-foot panels form each side of the hut, which is 20 by 48 feet

(inside measurement) with a clear floor area of 960 square feet. The structure

weighs about 10,000 pounds or approximately 10½ pounds per square foot of usable

floor area.

        The roof is slightly pitched, so the five panels at each end graduate from

8 feet 4 inches to 9 feet 4 inches in length. One panel at each end contains a

door, one being the entrance, the other for emergency use only. The corner panels

have mitered joints, and all joints throughout the hut are covered with felt

sealing strips. For permanent or semipermanent use, the joints are sealed

with mastic.

        Except for the two center end panels, each panel contains a round window,

16 inches in diameter, consisting of two panes of plexiglas separated by a

1-inch air space to reduce heat lose through the windows. Plexiglas was used

045      |      Vol_IIA-0462                                                                                                                  
EA-I. Roberts: Housing

in preference to ordinary glass to reduce breakage during shipment and

erection operations.

        Because of the hut’s excellent insulation, the heating and ventilation

system should provide adequate heat and air intake with low fuel consumption.

        Inside the building a bulkhead has been installed to form an entry

vestibule. This bulkhead may, however, be erected at any 4-foot station in

the building except at those stations where the roof beams are located.

        The roof beams and other elements of the hut’s basic framework are made

of aluminum. A sectional roof bean along the longitudinal center of the hut

rests on a support at each end, and on three evenly spaced transverse beams

in between. The transverse beams in turn are supported by st e a nchions fastened ✓

to the side panels. This structure rests on 2-foot-high foundation beams

which follow the outside dimensions of the hut, and has in addition a founda–

tion beam running longitudinally along its center.

        Large holes have been provided in the foundation beams as closely as

possible without affecting beam strength, to allow plenty of air to circulate

under the building. This will prevent melting of frozen ground and consequent

undermining of the foundation. An added advantage is decreased weight of the

beams.

        Assembly of the new Arctic Hut has been made extremely simple by the

designers. All parts, including the beams and supports, are easily connected

with pins and wedges. The only tools necessary for assembly are a mallet

and a socket wrench, the latter serving also as part of the door handle.

        The largest panel is about 4 by 10½ feet and the foundation beams are

12 feet long. The three 20-foot transverse roof beams, the heaviest units

046      |      Vol_IIA-0463                                                                                                                  
EA-I. Roberts: Housing

in the structure, weighs only 147 pounds. The shipping volume is 1,600

cubic feet.

        Since the structure may have to be assembled and disassembled under

severe weather conditions, the parts are all large enough to be handled easily

with mittens; there are no blind holes from which ice cannot be removed.

The use of plastic and fiber glass on all parts which connect the outside

and inside of the structure prevents the formation of ice on the inner

surface and reduces heat loss.

047      |      Vol_IIA-0464                                                                                                                  
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---

BIBLIOGRAPHY

1. American Society of Heating and Ventilating Engineers. Heating,

Ventilating, Air Conditioning Guide . N.Y., The Society, 1948.

2. Browne, Belmore. “Let’s Build a Snowhouse,” Natural History Magazine ,

Vol.55, No.10, pp.460-65, 486.

3. ----. ----. Reprinted for The Boy Scouts of America by special

permission of Natural History Magazine . (n.d.)

4. Close, Paul D. Building Insulation . Chicago, American Technical

Society, 1945.

5. Esbach, Ovid W. Handbook of Engineering Fundamentals . N.Y., Wiley,

1936.

6. Gilder, William H. Schwatka’s Search. Sledging in the Arctic in

Quest of the Franklin Records . N.Y., Scribner, 1881.

Describes camping and residing in snowhouses among Eskimos

who, on some occasions, had no fuel for warming them.

7. Jenness, Diamond. “The Life of the Copper Eskimos,” Canadian Arctic

Expedition, 1913-18. Report . Vol. 12: The Copper Eskimos,

Southern Party — 1913-16. Pt.A. Ottawa, Acland, 1923.

Describes pre-white Eskimo housing in Victoria Island and on

the [ ?] Canadian mainland opposite.

8. Koppes, Wayne F. Report on Characteristics of Snow Houses and Their

Precticability as a Form of Temporary Shelter. A Report to

the Subcommittee on Shelter and Clothing, Committee on

Sanitary Engineering and Environment, National Research

Council . Wash., D.C., Division of Medical Sciences, The

Council, 30 November 1948.

9. Murdoch, John. “Ethnological Results of the Point Barrow Expedition,”

U.S. Bureau of Ethnology. Annual Report , 9th, 1887-1888. Wash.,

D.C., G.P.O., 1892, pp.72-86. This publication, and the one by

John Simpson, describe Eskimo housing at Point Barrow, Alaska,

[ ?] as it was before E ru ur opean fashions came in. —

10. Peary, Robert E. Secrets of Polar Travel . N.Y., Century, 1917. This

book discusses snow houses, Eskimo houses of earth, bones , and — —

stone, and European-style winter quarters as built by Peary

himself.

048      |      Vol_IIA-0465                                                                                                                  
EA-I. Roberts: Housing

11. Petitot, E É mile. Les Grands Esquimaux . Paris, Plon, M— or N?ourrit, 1887. —

Describes pre-white Eskimo housing in northwestern arctic Canada.

12. Simpson, John. “Observations on the Western Esquimaux and the Country

They Inhabit; from Notes Taken During Two Years at Point Barrow...”

Great Britain. Admiralty. Further Papers Relative to the Recent

Arctic Expeditions in Search of Sir John Franklin, and the Crews

of H.M.S. “Erebus” and “Terror. ” London, 1855, pp.917-42.

13. ----. “The Western Eskimo,” Royal Geographical Society. Arctic

Geography and Ethnology. A Selection of Papers on Arctic

Geography and Ethnology. Reprinted, and Presented to the Arctic

Expedition of 1875, by the President, Council, and Fellows

of the Royal Geographical Society. London, Murray, 1875,

pp.233-75.

14. “Snow Caves,” The Polar Record , Vol.4, No.25, [ ?] pp.26-27,

January, 1943.

15. Stefansson, Vilhjalmur. Arctic Manual . N.Y., Macmillan, 1945.

16. ----. The Friendly Arctic . N.Y., Macmillan, 1921. This and the

previous book give — by explanation, description, photograph — ,

and diagram — explicit directions for the building and use of

snow houses. —

17. ----. The Stefansson-Anderson Arctic Expedition of the American Museum;

Preliminary Ethnological Report . 1914. N.Y., The Museum, 1919.

Its Anthropological Papers Vol. 14, Pt.1. This book contains

descriptions and diagrams of pre-white Eskimo earth and wood

houses in northwestern arctic Canada.

18. ----. “Corrections and Comments,” American Museum of Natural History. —

Anthropological Papers . Vol.14, Pt.2, pp.445-57. N.Y., The

Museum, 1916.

19. Teal, Jr., John H. Personal Communication November 30, 1949.

       

Palmer W. Roberts

       

Considerable parts of this

paper are based on the pub–

lished and unpublished writ–

ings of Vilhjalmur Stefansson.