Page:Highway Needs of the National Defense.pdf/104

84

Ton-mileage hauled

Table 8 gives the ton-mileage hauled by single-unit trucks and truck combinations from 1936 to 1947, inclusive. From 1941 to 1943 the total ton-mileage declined about 25 percent, but the ton-mileage moved by combinations declined only about 7 percent. Prior to the war the ton-mileage was divided almost equally between single-unit trucks and truck combinations, whereas, beginning during the war and continuing subsequently combinations have carried about twice as much as single-unit trucks.

Heavy loads

The heavier wartime loads were due in part to the lifting or relaxing of restrictions on sizes and weights by the States, in order to permit the maximum possible utilization of our trucking capacity during the emergency. The result was greatly to increase the frequency of heavy gross loads and heavy axle loads, thus increasing the strain on pavements and bridges.

Figure 14 shows the number of heavy gross weights per 1,000 trucks and combinations in a prewar period (1936-38) and each year from 1942 to 1947, inclusive. Of each thousand vehicles using the highways, the number weighing 30,000 pounds or more was almost three times as great in 1943 as in the prewar period, and the number weighing 50,000 pounds or more increased fivefold, from 3 to 15 per thousand.

igure 15 shows that the increases in heavy axle load frequencies were of similar proportion, and that this trend has persisted into the postwar period. Thus the upward swing in heavy axle load frequencies, which was started by the relaxation of weight limitations during the war, has not yet been arrested.

BUS TRANSPORTATION IN WARTIME

The sharp reduction in the use of passenger automobiles during World War II imposed unprecedented loads on public transit facilities. The numbers of busses in city and suburban service increased from 37,855 in 1941, to 45,610 in 1948, and 48,525 in 1944. Intercity busses increased in number from 18,420 in 1941 to more than 28,000 in 1943 and 1944. The Office of Defense Transportation reported that intercity motor carriers of passengers transported 209 percent more persons in 1944 than in 1941; and that local transit operations