1941: Civil Engineering

Defense construction dominated the civil engineering field in 1941 as in 1940, but to a much greater degree. Due to defense work, the total construction volume exceeded $11,000,000,000, as compared to $8,000,000,000 in 1940, which in turn had broken the all-time record set in 1928 and 1929.

Defense Contracts.

Contract awards for engineering construction for the year as compiled by Engineering News-Record totaled $5,868,700,000 as against $3,987,000,000 for 1940 (these figures do not include small house construction, nor any waterworks, drainage or irrigation work below $15,000, other public works below $25,000, industrial buildings below $40,000, and other buildings below $150,000). The principal classifications covered in the above totals are as follows: Waterworks, $76,698,000; sewers, $88,719,000; bridges, $111,628,000; earthwork, $245,221,000; streets and roads, $582,847,000; industrial buildings, $496,176,000; commercial buildings, $485,683,000; public buildings, $2,785,585,000; unclassified, $996,142,000.

Predictions as to the construction prospects in 1942 are difficult to make. The Department of Commerce, before the start of war with Japan, estimated that construction would decline from $10,500,000,000 to $8,500,000,000, due to priorities on defense material and curtailment of non-defense construction. However, before the year closed the Government had inaugurated a speed-up of defense work that is expected to produce a further increase in defense construction that will more than offset the cut in non-defense work. The Office of Production Management now estimates the 1942 total at $11,250,000,000, slightly more than 1941. Early in December, a few days after war was declared, Congress passed a $10,000,000,000 appropriation act to speed up the nation's war effort and is expected to appropriate more money for further expansion of war activities early in the new year. That will further curtail both men and materials available for nondefense work and will mean almost complete stoppage of all building work not directly connected with defense or the housing of defense workers, drastic curtailment of street, highway and bridge building except to serve war industries and military bases and elimination of all water supply and sewage disposal operations except those made necessary by new communities of war workers. Power projects that can be brought into service this year or next will be speeded up but most other power work will be stopped. Similarly, flood control projects other than those protecting essential industries are expected to be postponed. Over against these curtailments there is to be an expansion of civil airport construction because a large number of high-grade airports is essential to air defense of the nation and both military and civil needs can be met by one airport in most instances.

Building Construction.

Building construction during 1941 centered mainly in defense activities, and it is in structures erected for such purposes that most of the noteworthy developments occurred. The industrial type of building dominated this work, with high one-story structures for the manufacture of airplanes, engines, tanks and trucks making up the larger group. These buildings, covering as much as 20 acres in area in some instances, were simply framed except in the case of plants for the manufacture of airplanes where wide unobstructed areas were called for. They are notable chiefly for the improvements in wall design that they produced and for the greater use of basements and underground ducts and passages to facilitate the movement of men and materials free of the manufacturing operations on the main floor.

Wall types vary widely, some being solid and some being provided with sash or panels of glass brick. Wall materials may be brick, concrete, plywood, asbestos, cement, fiberboard or steel, frequently faced on the inside with layers of insulating and sound absorbing materials. Much attention was given to insulating both walls and roof areas, primarily because air conditioning was accepted almost as an essential element of such structures to increase the efficiency and add to the comfort of the workmen.

Improved lighting also is an outstanding characteristic of these new factories, fluorescent lighting being most commonly used.

A few plants were designed for blackout, and some were designed specifically to afford a large measure of protection to employees in bombings. The more extensive use of basements and underground passages was due in part to recognition of the protection they would afford in air raids.

Airplane plants are notable chiefly for their large roof spans designed to give wide, unobstructed floor areas, the largest being the 300-ft. roof trusses of the Boeing plant addition at Seattle. In that plant production advances longitudinally through the 300-ft. wide bays to end doors having a clear opening 295 ft. wide and 35 ft. high.

At the Boeing plant in Vancouver, bc, columns and roof trusses are of timber, the trusses having a span of 128 ft., and side walls are of plywood panels treated to be weather resistant.

A distinct departure from past practice in factory design is the 400 x 1,000-ft. airplane plant for the Glenn L. Martin Company near Baltimore. Its 400-ft. width is made up of two 200-ft. trusses, the heavy columns at midspan being designed to carry the lateral force of a wind on a 100-ft. section of 66-ft. high wall. The 200-ft. trusses are pin connected to the wall columns, supplemented by welding after the dead load is in position. Longitudinal trusses are of cantilever design and 100-ft. span.

Other unusual structures built for war purposes include a variety of special buildings at munitions plants designed to limit the effect of explosions to a single building or to a cell where the explosion occurs. Generally, these buildings are characterized by heavy walls and light roofs that blow off easily. Other structures are large warehouses with roofs of thin reinforced concrete barrels carried by overhead concrete beams, and large concrete hangars in which deep arch ribs over the roof support a thin arch roof of 294-ft. span and 84-ft. rise.

Unrelated to war work are two notable structures of steel, both experiments in applying designs developed for industrial purposes to other uses. One is a recreation center for the Chicago Bridge & Iron Co. consisting of an elliptical welded steel plate dome, 80 ft. in diameter, supported only on steel plate side walls. An annular lean-to of welded plate accommodates the air conditioning plant, kitchens and other services. The interior surface is lined with an insulating and acoustical material sprayed directly on the steel and built up to a thickness of 2 in. The other structure is a recreation hotel in north Georgia, completed by the R. G. LeTourneau Company late in 1940, consisting of a 100-ft. diameter domed lobby with radiating wings one story high, the whole structure being frameless and built of welded cellular units made of rust-resisting steel.

Housing.

Defense housing took a dominant position in the house-building field in 1941. In all, the Federal Government allocated over $1,000,000,000 to such work and by giving encouragement to those with sound ideas as to how speed and economy could be obtained, produced some quite radical innovations. Private house building, except units costing at or below $6,000 in defense areas, which could get priorities, was badly checked toward the latter part of the year.

The Government insisted that all Federally financed defense housing built near military bases or to serve workers in defense industries be demountable. This stimulated prefabrication and encouraged the use of materials not common to house building. Prefabrication ranged from simple precutting and notching of lumber to factory fabrication of wall units, assembly line methods being applied to some of the larger operations. The Tennessee Valley Authority carried prefabrication to the point of building complete sections of one-story houses on an assembly line and shipping them to the site on trucks where the only remaining operation was bolting the units together on foundations built in advance of delivery.

The Public Buildings Administration set up a housing project at Indian Head, Md., as a sort of laboratory and gave ten fabricators an opportunity to show what they could do in the construction of prefabricated houses, including a demonstration of demountability through the transfer of 168 houses to Quantico. Va.

In addition to lumber, materials used included steel, plywood, compressed fiber, repulped newspapers, combinations of plaster and asbestos, and a small amount of concrete. Some units were made with wall panels of a single slab of insulating material having a weather-resisting exterior surface and an appropriate material for interior finish on the other face.

Bridges.

Defense work resulted in little curtailment of bridge construction in 1941 as compared with 1940, primarily because most bridge projects were on the strategic highway network and so were entitled to high priorities. Contracts totaled $120,000,000, only slightly below the 15-year average. Considerable curtailment is in prospect for 1942.

Progress in design centered chiefly in steel arches, three notable structures being the new Rainbow Arch at Niagara Falls, replacing the old bridge that was wrecked by an ice shove in 1938; a new bridge over the Chesapeake & Delaware Canal at St. Georges, Del.: and a bridge over the Mississippi River at Dubuque, Iowa. The Niagara bridge is a 950-ft. hingeless arch, longest of its type in the world. The bridges at St. Georges and Dubuque are tied arches, 540 and 845 ft. long, respectively. Simplicity of detail and ease of erection are the major advantages of the tied arch, which is relatively new to American practice.

Long plate girder spans continue to gain in popularity with American bridge builders. Most conspicuous among those started in 1941 is the Connecticut River crossing at Hartford where the three main river spans are to be formed as a continuous plate girder composed of a central 300-ft. span flanked by 270-ft. spans on each side, making it the longest continuous plate girder in this country. This bridge met with a serious accident on Dec. 4 when collapse of falsework under the first 270-ft. span as it was nearing completion dropped the erected steel and the large erector derrick into the river, killing 16 men.

Erection of the Pitt River bridge in California, conspicuous chiefly for its 350-ft. high piers, which are to be almost entirely submerged in the reservoir behind Shasta Dam, was substantially complete in 1941. Another bridge conspicuous for its piers is the new toll bridge over the Thames River at New London, Conn. The bridge has a clear height of 137.5 ft. above mean low water and the deepest piles under the piers are 155 ft. below water level. Use of steel H-column piles, a relatively new development, greatly simplified this bridge job.

Plans for reconstruction of the Tacoma Narrows bridge that collapsed in November 1940, have progressed to the point of applying to the War Department for a permit to build a new bridge having a wider deck and higher towers but somewhat less clearance over the navigable channel. Its design will incorporate the latest developments in knowledge of aerodynamic stability.

Three large lift bridges were completed during the year, a 365-ft. span at Jacksonville, Fla., a 332-ft. span over the Passaic River near Newark, N.J., and a 224-ft. double-deck bridge over the Piscataqua River at Portsmouth, N.H. Work is well along on the double-leaf bascule bridge on State St. in Chicago, 120-ft. wide and of 245-ft. span.

One leaf of the 27-year-old double-leaf bascule bridge of the Canadian Pacific Railway over the navigation canal at Sault Ste. Marie, Mich., longest of its kind in the world, collapsed under a locomotive in September, due, it is believed, to failure of the interlocking system. The bridge was not seriously damaged and is back in service.

Highways.

Highway building in 1941 fell below the all-time record for new construction set in 1940, due chiefly to delays growing out of priorities on war materials. Reinforcing steel was especially difficult to get, and as a result some state highway departments abandoned its use in concrete pavements, increasing the thickness of the concrete somewhat to offset the lack of steel.

Highway legislation passed in 1940 called for expenditure of federal-road funds as far as possible on the strategic highway network, a nation-wide system totaling 75,000 miles and designated by the War Department as important to the defense of the nation. Early in 1941 the Public Roads Administration reported to the President that about 14,000 miles of this system needed strengthening, that 2,436 bridges were substandard and that 2,830 miles of access roads to military camps were needed. This was expected to increase road building, but the President did not ask Congress for money for the work until July, and because of a disagreement between Congress and the President as to the handling of the money, legislation was not finally approved until November. No money for defense highway work was appropriated until after war was declared in December. Work under the normal Federal-aid appropriations continued at a reduced scale.

Further curtailment of new highway construction is anticipated in 1942 due to war work, but as the war effort is expected to add greatly to the heavy trucking on highways, maintenance expenditures will have to be materially increased.

Specifications for highways of the strategic network were issued by the Public Roads Administration in March to aid in insuring that road surfacing and bridges will be adequate to carry Army tanks and heavy motorized equipment. These specifications call for almost no precautionary measures on highways built to meet the H-20 loading of the American Association of State Highway Officials, now used in New York and in some metropolitan districts in other states, and few precautionary measures are needed on roads built to the H-15 loading, now standard for new construction in most states. Notable in the specifications was the recommendation that 8-ft. wide shoulders be built on all highways carrying more than 1,800 vehicles per hour, to permit mechanized military units to clear the traveled road when not in motion.

The Pennsylvania Turnpike, first major toll road to be built to modern standards, completed its first year of operation in November. The total income was close to the preliminary estimate but operating costs were about double the estimate. Despite this increase, the road earned enough to pay interest and amortization charges on the bonds issued by the state, but when the Federal grant of 45 per cent of the cost is included, the road is far from being a self-liquidating undertaking. Extension of the Turnpike west to the Ohio or West Virginia line was authorized by legislation passed in Pennsylvania in June but no work has been undertaken.

Connecticut continued work on Wilbur Cross Parkway, an extension of the Merritt Parkway which, with that parkway, when completed will give a superhighway across Connecticut about on an airline between New York and Boston.

Additional sections of New York's great East River Drive were opened during the year, but some of the more difficult work remains to be done before the whole drive can be opened. Work was begun on twin vehicle tunnels from the lower end of Manhattan Island to Brooklyn following completion of construction shaft started in 1940, but completion of the project, originally scheduled for 1944, will be delayed by the war. Work on the second tube of the Lincoln Tunnel at New York was resumed during the year due to rapid increase in traffic passing through the single tube that was opened in 1937.

A vehicle tunnel 3,400 ft. long having a two-way roadway 21-ft. wide under the Mobile River at Mobile, Ala., was opened on Feb. 20 as a toll facility.

Philadelphia has begun work on a system of express highways across the city on lines of major through travel to relieve congestion on existing streets, the state sharing in the cost.

Completion of a highway across the Isthmus of Panama, beginning and ending in the Canal Zone but largely in the Republic of Panama, is actively under way with the object of completing the work before the spring rains.

Water Supply.

Construction of water supply and sewage disposal facilities in 1941 continued at the high record of previous years despite the curtailment of normal public works that came with the defense effort. This was due to the establishment of new communities to house defense workers or the expansion of old communities for a like purpose, and also to meeting the need for water supply and sewage disposal facilities at the many cantonments being built by the Government.

A major addition to the nation's water-supply facilities is the 100-mgd. water softening and filtration plant at the western end of the 280-mile aqueduct that brings Colorado River water to the Los Angeles metropolitan area. Tunnel driving on the aqueduct for New York's new Delaware supply lacked only one half mile of completion of the 85-mile total at the end of 1941, and lining is in progress. Late in the year a start was made on the 145-mile steel pipeline across the Florida Keys to reinforce the limited supply at Key West, now the site of a great naval base.

The largest installation yet made of so-called radial well water collectors was that made at the big smokeless powder plant at Charlestown, Ind., 16 units of 10 mgd. capacity. In this system, underground sources are tapped by pipes projected radially from a large central well.

Technical progress in water purification was noteworthy. Rapid advances were made in adoption of break-point chlorination (briefly noted in 1941) for the control of tastes and odors, and two installations of 'potential chlorination' were made. This is a method of electro-chemical control of the application of chlorine which automatically regulates the supply of chlorine to the correct amount regardless of changes in flow or in chlorine demand. Further developments in the use of ozone also were reported, including the demonstration of a mobile ozonator for use of troops in the field.

Sewage Disposal.

Much sewage disposal work found its origin in defense, meeting the needs of new defense housing or serving military camps. In this latter field, the relatively new method of high-capacity filtration recorded the most extensive use it has yet attained, due doubtless to its flexibility, ruggedness under varying loads and lower construction and operation costs as compared with standard trickling filters.

New developments include perfection of equipment for automatic control of chlorination which uses a new principle involving electrical potential measurement of the sewage as a direct indicator of its chlorine demand.

Important improvements in settling tank design are being included in the new Bowery Bay plant for New York City; at Springfield, Mo., the first installation was made of multiple-tray clarifiers, a new device in sewage treatment.

Recovery of by-products from sewage disposal was advanced during the year by studies at Atlanta relating to use of compressed sludge gas to drive motor vehicles. Estimates showed a possible saving of $8,000 annually to the city, but the war stopped plans for putting the proposal into effect. The gas is now being used as fuel in a nearby pumping plant.

In Baltimore, the Bethlehem Steel Company is using 40 mgd. of the highly purified effluent from the city's disposal plant for industrial purposes to replace a depleted ground-water supply. See also ARCHITECTURE.