1940: Civil Engineering

Trite but true is the phrase that 'Construction is the spearhead of our defense effort.' As a result of defense work, 1940 was the biggest year in history for construction of the heavier civil engineering type, bigger even than 1929. Residential work exceeded that of any year since 1929, but fell considerably short of a record. Total construction for the year was about $8,000,000,000 compared with $7,000,000,000 in 1939. More than $2,500,000,000 in new construction reached the contract stage in the last half of the year, largely as a result of the speed-up of defense construction.

Private and public construction awards both participated in the gains over 1939. Public volume set a new high mark, exceeding by 34 per cent the record established in 1939; the tremendous Federal total, nearly $1,500,000,000, also a new all-time high, was responsible for the public gain, and topped the preceding year by 311 per cent. Private awards climbed to the highest point reached in 1930 and increased 31 per cent over 1939.

Industrial building construction was the important factor in the private gains. The total, $594,000,000, eclipsed the record of 1929 and more than doubled the volume of 1939. Industrial building included factories for aircraft, engines, machines and machine parts, all products closely allied to defense.

The gains in the public construction field were more widely distributed, and three new high marks were established in individual classes of work. Public buildings rose to unprecedented heights, topping the previous high of 1939 by 102 per cent. Some of this was due to cantonment work and some to Government-owned manufacturing plants which, if they had been financed by private funds, would have been in the industrial building total. Air-base, airport and shipyard construction aided materially in boosting unclassified public construction to a new pinnacle, 52 per cent over 1939. The third record established in the public field was in streets and roads, which increased 5 per cent over the record high of 1939.

There were losses. But in view of the great emphasis placed on national defense construction, only one of these is surprising, namely, bridges, which attained only 80 per cent of the 1939 total. The other two drops were in waterworks, which registered 43 per cent of the 1939 total, and in sewerage, which registered 57 per cent.

Not for a decade have construction prospects been so promising as they are for 1941, though they result in the main from a war boom and are liable to the hazards succeeding such activity. The tempo is already established, and only such an unexpected event as Germany's sudden and complete collapse could slow down our defense preparations, which in their present stages are predominantly construction. Of the $2,000,000,000 for construction in the Federal defense appropriations, nearly one-half remains as a backlog for 1941 contracts. Additional Congressional appropriations for shipyards and industrial plants are certain. More money for airfields may reasonably be expected. Highway building will not decline in amount and could increase. Steel mill expansion, already begun, may be greatly extended. Though predicting trends is risky, it seems reasonable upon the best available information to expect about an 11 per cent increase in construction for 1941.

Civil engineering and construction activities are most easily considered if divided into the various types of work involved, namely, buildings, highways, bridges, sewage disposal, water supply, etc. These are considered in turn below.

Building Construction.

The year 1940 was dominated by building construction of the factory type. Huge plants for the manufacture of powder, shells, tanks, airplanes and ships got under way and are supplemented by Army and Navy warehouses, ammunition depots, airplane hangars and cantonments. Technically, there were few important advances recorded because the objective was speed, which leaves little time for innovation.

Both the Army and Navy tried out thin concrete shell roofs for a few hangars, but for the most part such structures used steel frames. These steel-framed hangars, however, reflect great advances since World War days. For one thing, the maximum 110-ft. hangar width of the World War has been replaced by openings up to 250 ft. wide. The Army is building three types of hangars, the most common being the tied steel arch of 275-ft. span, 200 or 250 ft. long, and having unobstructed door openings 250 x 37 ft. And to accommodate the tail of the planes, which in the largest machines reaches a 45-ft. height, a lift door 15 ft. square is placed over the center of the main door openings. In Alaska the interior of the hangars is vestibuled by placing sliding doors similar to the main door at mid-length so that the inner or working compartments can be kept at a reasonable temperature.

The Navy uses simple trusses of long span rather than arches to support the roofs of its hangars. The standard seaplane hangar has a net floor area 240 x 320 ft. in plan, with two 160-ft.-wide door openings. Land-plane hangars are 200 x 220 ft. in plan with two 110-ft. door openings. Concealed or protected hangars are not favored as yet. The principle is that the place for planes is on the field ready for instant service. Accordingly, the hangar enclosure is built for weather protection only and not to resist bombs.

Most spectacular of the buildings at Navy air stations are the huge assembly and repair shops. These are being built initially with such plan dimensions as 640 x 580 ft., and all are so laid out that floor area can be doubled if needed. The Army also uses huge buildings particularly at supply and repair depots at one depot, for example, an engineering shop is 770 x 640 ft. in plan, and there is a supply building 480 x 860 ft.

Permanent barracks are of all types and utilize every conceivable material. Not only are they well built but considerable attention is being paid to make their appearance attractive.

Housing at naval shore stations utilizes many of the advances incorporated in the best of low-cost housing projects developed over the past few years, including insulation, acoustic ceiling and poured concrete foundations. Even the Army cantonments, which are of more temporary nature, are many times more convenient and livable than the 1917 variety.

Following closely on the changes in the New York City building code to permit welding, several buildings of this type were constructed. Most notable is the airlines terminal on East 42nd Street containing five stories and three basements in which all of the framing is arc welded. Several trusses of 70-ft. span weigh as much as 30 tons each. Because buses, which take passengers to the airports, are handled within the building by means of ramps and elevators, there is much complicated framing which required the development of many ingenious welded details.

Several important office buildings were completed during the year. In Des Moines, Iowa, the Bankers Life Co. moved into a new seven-story building notable for its 55-ft. clear span working area, enameled steel interior finish, radiation from pipes in the walls, ventilation through perforated metal ceilings and an exterior of granite and limestone. In Houston, Texas, the 16-story Mellie Esperson building was given a complete air conditioning installation; to fit the ducts into the building with greatest economy and least damage to architectural appearance, a special shallow beam framing was developed for the corridor buys down which the ducts were laid. Most notable reinforced concrete building of the year was Wesley Memorial Hospital on the Northwestern University downtown campus in Chicago. The central unit is a 21-story steel frame building; radiating from it are four 16-story wings of reinforced concrete.

Auditorium buildings were not so numerous as previously, but Buffalo completed one with a seating capacity of about 15,000 persons. Covering an entire block, the roof is supported by pin-connected trusses of 258-ft. span weighing 62 tons each. Numerous office buildings were built in Washington, D. C., one of the largest being the War Department building. Seven stories high and of steel frame construction the new building has 310,000 sq. ft. of floor space, which it is planned to increase to 1,200,000 sq. ft.

Great emphasis was placed upon defense housing toward the end of the year, the most interesting phase being the decision to utilize pre-fabricated units on some of the projects. The USHA slum clearance program continued to turn out well-planned and permanent quarters in a number of cities. Most spectacular of all housing during the year was the Parkchester development of the Metropolitan Life Insurance Co. in the Bronx, New York City. Consisting of 51 buildings ranging up to 12 stories in height, it is a self-contained community for about 40,000 residents. Apparently as a result of the success of this initial venture, the company awarded contracts late in the year for a similar though smaller housing development in San Francisco.

Aircraft factories turned in the best record of rapid construction, many of them doubling and tripling their floor space in a matter of months. Most notable of technical developments was the wide utilization of basement corridors in the Boeing plant at Seattle to take workmen from the factory gates to the point in the building where their job was located. Also, a number of windowless aircraft factories, given the wartime name of 'blackout' factories, were started, notably North American Aviation at Dallas and Grumman Aircraft at Bethpage, L. I. Such factories require controlled conditions of lighting and ventilation and are claimed by their proponents to promote the efficiency of the workmen. Because most aircraft factories have large expanses of glass in roof and side walls and thus would make prominent bombing targets at night, there was some talk of installing masking devices to shut in the light, but nothing of note in this direction has yet been done. (See also HOUSING DEVELOPMENTS.)

Highways.

More money was spent for roads in 1940 than in any other year in history; this same statement was true for 1939, so that the road building tempo is gradually being increased. The 33,000 miles of roads built in 1940 (in 45 states reporting) is an 11 per cent gain over the 1939 mileage. Some 52 per cent of the total is 'dustless' and only 11½ per cent is real 'pavement.' 'Non-dustless' surfaces accounted for 17½ per cent of the mileage while the balance of the 1940 total was merely 'graded and drained' and not surfaced.

Per capita spending for roads was $6.60 west of the Mississippi, $6.25 in the Far West, $6 in the South, $4.54 in the Middle West, $5.24 in New England, and $3.54 in the Middle Atlantic States. In New England 43 per cent of the highway money is spent on maintenance, in the Far West 38 per cent, in the Middle West 33.6, in the Middle Atlantic States, 31.5, west of the Mississippi 29, and in the Southern States 29.

Despite much talk about defense roads, little was done in 1940 to implement some of the plans that had been developed. Three major road problems raised by the preparedness program still need to be solved; how to finance the construction of access roads to the new Army camps; how to prevent serious congestion around plants engaged in military orders; and how to bring the system of strategic highways up to military requirements without neglect of normal commercial needs. Most urgent and simplest is that of camp access roads. It requires, however, funds from Congress and these have not been appropriated. The strategic road system will probably be taken care of in the normal course of highway development, but congested roads in industrial areas will need special attention.

Completion of the Pennsylvania Turnpike between Harrisburg and Pittsburgh, a toll road of the super-highway type incorporating every modern development for the rapid movement of traffic, was the outstanding highway event of the year. After three months of operating experience, the road is considered a distinct success, and plans are under way to extend it to Philadelphia when and if financing can be arranged. The most unusual operating result is that few automobiles can stand the sustained high speeds that are possible on the Turnpike; mechanical failures have been high and tires have been seriously damaged. The Turnpike consists of four 12-ft. lanes, two in each direction separated by a 10-ft. median strip in which shrubs are to be planted to form a separating barrier. Through the mountain tunnels, of which there are seven aggregating a total length of 6.8 miles, there are but two lanes 11 ft. wide. Experience to date has shown that the two-lane tunnels do not delay passenger vehicles by requiring them to merge with truck traffic because the trucks travel at the maximum speed permitted, which is 50 miles per hour approaching a tunnel and 35 within the tunnel. The 161-mi. road cost about $67,000,000.

Another great road-building job of the year was New York City's Belt Parkway. A little over 31 miles long, it cost about $28,000,000. Both highways give some indication of the tremendous cost of providing highway facilities that adequately meet traffic requirements. The Belt Parkway is being extended from its western terminus in Brooklyn to a connection with the Battery-Brooklyn tunnel now under construction under the upper bay at New York City. With the completion of this link the entire city of New York can be circled on a grade-separated highway.

Bridges.

The most important bridge development of 1940 was not bridge building but a bridge collapse. On Nov. 7, wind wrecked the 2,800-ft. main span of the Tacoma Narrows suspension bridge which had been in service less than six months. The bridge had been one of the achievements of the previous year, notable for its extreme slenderness and shallow stiffening members which were of plate girder type. From the time it was opened the bridge had exhibited disturbing lengthwise oscillations in its deck, and these were being studied by models when the collapse occurred. The collapse, however, resulted not from these up-and-down oscillations but from the fact that they suddenly changed to a twisting and sidewise rolling motion under aerodynamic influences. This twisting and rolling eventually tore the suspended deck loose from its suspender cables, dropping it 200 ft. into the waters of Puget Sound.

The failure has been likened to the failure of airplane wings under a type of vibration known as flutter. This vibration, not previously encountered in engineering structures, raised important new problems. Until studies now under way are complete, little can be said as to the cause of the collapse other than that the bridge was too flexible. The solid stiffening girders may have played a part in building up the irresistible forces, but on other bridges where they have been used — Bronx-Whitestone in New York City, Thousand Islands across the St. Lawrence River, and Deer Isle in Maine — and where vertical oscillations have also occurred, such oscillations have been reduced or eliminated by installing inclined stay cables at the towers. Plans are under way to rebuild the Tacoma Narrows bridge, salvaging, if possible, the tower, main cables and side spans which are still standing.

The Washington Toll Bridge Authority, owner of the Tacoma Narrows Bridge, is also the owner of the Lake Washington floating concrete bridge which was opened to traffic during the year. This novel structure consists of large concrete boats 350 ft. long and 60 ft. wide, placed end to end and carrying a four-lane roadway nearly 7,000 ft. long. At the shipping channel two of the pontoons are built to telescope providing an opening through which the boats can pass. Also on the Pacific Coast the great Pit River bridge on the railroad and highway line around Shasta Dam progressed to the point where steel erection began. This bridge contains the tallest concrete piers in the country, two of which exceed 350 ft. in height. It will carry the highway on the top deck and the railway on the bottom deck of a truss bridge having spans varying from 140 to 650 ft.

Four bridges were completed across the Mississippi River during the year, one each at Baton Rouge, La., at Natchez, Miss., at Greenville, Miss., and at Rock Island, Ill. The Natchez bridge with an 875-ft cantilever span contains the longest span of any Mississippi River bridge. The Rock Island Bridge is notable because it consists of a series of steel tied arches, varying in length from 394 to 539 ft. Such spans are uncommon, but the year witnessed start of construction of another bridge utilizing them, located on the DuPont Highway over the Chesapeake & Delaware canal at St. Georges, Del. This structure, which will have a span of 540 ft., replaces an old lift span.

Plate girder bridges continued to increase in length of span. The record at present belongs to a 271-ft. span in the lakefront approach to Cleveland's new Main Avenue viaduct. Work, however, has begun on a new bridge at Hartford, Conn, across the Connecticut River in which plate girder spans up to 300 ft. will be used. The most extensive use of plate girders and one of the most unusual occurred in the Thomas A. Edison Bridge built by the New Jersey Highway Department over the Raritan River at Perth Amboy. Opened during the year, this bridge contains eight 200-ft. spans and one 250-ft. span raised to a height of 135 ft. over the shipping channel. The 250-ft. span girder is 21 ft. deep over the supports, a maximum for this country.

In Lorain, Ohio, the country's longest double-leaf highway bascule bridge, 333 ft. between trunnion pins, was finished late in the fall. The other notable movable bridge of the year was built over the Piscataqua River at Portsmouth, N. H. A 224-ft. lift span, it is notable for the fine architectural appearance of the towers. It is a double deck structure with a highway on the upper deck and a railway on the lower.

Another New England bridge that deserves important mention is the Merritt Parkway crossing of the Housatonic River. Two unusual features characterize this bridge — the use of one-leg bents and of 1,824 ft. of open steel grid flooring, the largest installation of this type of flooring to date. The bridge is of plate girder type and the one-leg bents were adopted to give increased width in the shipping channel where conventional two-leg bents would have formed an obstruction or made it necessary to increase the span length unduly.

Sewage Disposal.

Following a decade of great activity, sanitary engineering dropped back to more nearly normal dimensions. Instead of an expenditure of $150,000,000 for sewage disposal as in 1939, the year 1940 witnessed only $91,000,000 worth of new facilities. Technical advance, however, kept up a reasonable pace. The high rate shallow filtration process — a novelty just a few years ago — received great impetus by forty new installations said to be 30 per cent lower in construction cost and as much as 40 per cent lower in operating cost than the standard trickling filter system.

Combined disposal of garbage with sewage, talked of for many years and experimented with for several, came into prominence with the completion of major plants at Rock Island, Ill., and Gary, Ind. The pioneer installation was made in Lansing, Mich. in 1938. Other plants are at Goshen, N. Y., Findlay, Ohio, and Marion, Ind.

Considerable controversy arose during the year over the utilization of sludge for fertilizer. Many new converts were obtained by those favoring sale of sludge as fertilizer; but experience at Milwaukee, one of the biggest and oldest producers of fertilizer from sludge, dispels the thought of profit. In Milwaukee it costs $23 to produce a ton of fertilizer, while the net return is about $15. Chicago, however, has been shipping sludge to Florida, and this has captured the imagination of some major cities.

Not much progress was made in stream pollution abatement but a step forward was registered when Congress approved the formation of interstate compacts for the control of pollution in the Ohio and Potomac Rivers. An extensive study of river uses and abuses is being made of the Ohio River, looking forward to a program of remedial measures for stream cleanup in a 14-state area involving 200,000 sq. mi.

Progress in sewage disposal as measured by new plant construction will continue to be slow because sewage disposal is not a prime national defense need. Several of the larger cities, notably Philadelphia, Boston, Louisville and Los Angeles, have plans for major expenditures but these will not materialize this year. The biggest jobs under way are the $10,000,000 addition to Chicago's Southwest plant and the $6,000,000 program for several plants in New York City.

Water Supply.

Outstanding among the new technical developments in the field of water supply in 1940 was the introduction of break-point chlorination for the elimination of taste and odor. The new technique involves the application of chlorine to a predetermined dose, at which point a change of condition will occur resulting in a sudden drop of residual chlorine. If more chlorine is applied this is followed by a breakdown of taste producing substances. A different form of attack on taste and odor problems, using ozone, was launched at Denver, Pa., where a 300,000 gal. filter plant was built and provisions made to apply ozone gas to the water.

Big water supply undertakings included the Baltimore tunnel, the Boston aqueduct, the Chicago filter plant, the Delaware aqueduct for New York City, and the softening plant for Colorado River aqueduct water in southern California. Also Toledo, Ohio completed a 108-in. intake conduit three miles long into Lake Erie, which is supplemented by 9 miles of 78-in. pressure main to a new 80,000,000 gal. daily purification plant. Wichita, Kans., draws water from a new prairie well field to its new plant through a 48-in., cast-iron pipeline. Work on the 320,000,000 gal. South District filtration plant in Chicago has progressed rapidly, and the substructure of the plant is substantially complete.