Page:America's Highways 1776–1976.djvu/462

 In other developments of construction equipment, the front apron was first placed on scrapers in 1933, making a 12-cubic yard load possible. Hydraulic controls were placed on power shovels in 1937, then in 1938 the self-propelled scrapers made it possible to move earth at a much faster pace. The compaction of earth was also keeping pace as the ballastable rollers were introduced in 1936. Paving equipment was being revolutionized as the traveling concrete paver, introduced in 1926, made use of the skip lever to activate the water measurement and the timing of the mix. In 1932, the dual-drum traveling paver helped to increase production of concrete for pavements. Internal vibrators for portland cement concrete were patented in the United States in 1935 and soon used widely to assist in the consolidation of concrete in the forms. Bituminous paving equipment was being developed as the road mix machine was introduced in 1929, and the bituminous paver placed on the market in 1932. This equipment provided more rapid construction of improved asphalt pavement at lower cost.

As can be seen, many of these developments took place during the Depression years, when so many industries were virtually shut down because of the national economic situation. The highway industry was probably one of the industries that was least injured by the Depression. By using highway work as one of the “make work” projects of this period, the National Recovery Act brought employment close to the homes of the unemployed. It was estimated that for every person directly employed on road work, there were two others employed in the manufacture and transportation of road materials and equipment.

Thus, while being used as one of the “tools” to fight the unemployment of the Depression, an added benefit was that the highway industry grew in capacity and was ready for the program of interregional highways that was recommended by the report Toll Roads and Free Roads in 1939. The program discussed in the report became the basis for the plan of the National System of Interstate and Defense Highways as we know it today.

A self-propelled, self-loading scraper.

The Interstate program had to be postponed, however, as the country plunged into World War II. The Nation’s roads took a hard beating during the war years, as construction and maintenance were slowed considerably. The road work accomplished was largely composed of correction of critical deficiencies on main highways essential to war transportation.

All noncritical highway work was deferred, and the use of critical materials was reduced to a minimum. New construction was largely confined to access roads to new military installations, defense plants, ports and the like. World War II left its imprint on the highways. Many miles of the oldest highways, already worn and obsolete and scheduled for replacement, were kept in service. This situation, already bad, was accentuated by the wear and tear of continuous streams of war traffic. Thus, the mileage of roads no longer adequate for the traffic carried and difficult to maintain in service, grew in size throughout the war.

Due to the loss of personnel by State highway departments to the military forces and defense plants and the unavailability of new equipment, spare parts, tires and fuel, it was necessary for most States to sharply reduce their maintenance activities. The quality of maintenance suffered. Only routine surface maintenance, resurfacing, and resealing were intensified to preserve the existing surface, whatever type it happened to be. Operations to maintain shoulders, clean ditches and culverts and mow the weeds were performed only as time, manpower, and equipment allowed.

As the war in Europe neared an end, Congress passed the Federal Aid Highway Act of 1944. This was a far-reaching piece of legislation. It authorized $500 million for each of the first 3 postwar years; it authorized, for the first time, the use of Federal-aid highway funds in urban areas ; it provided authorization for the construction of a Secondary Road System; and it directed the designation of a National System of Interstate Highways. The funds authorized in this legislation made possible an expanded and 456