Page:America's Highways 1776–1976.djvu/463

 essential program of construction and reconstruction of highways which had borne the burden of heavy wartime traffic with a minimum of maintenance or betterment activity.

This grader was designed to be as flexible as the human wrist. The blade shown here is especially useful for fine grading on slopes and ditches; a bucket blade is used for excavation work.

This period of 1944–64 was one of greatly expanded highway activity. Public Roads worked closely with the AASHO, the Highway Research Board (HRB), and the various industry associations, especially in the areas of coordination of construction practices, research, and the development of standard specifications.

In 1948, AASHO published its Policy on Maintenance of Roadway Surfaces (revised in 1961). Then in 1949, AASHO came out with its Manual of Highway Construction Practices and Methods. These two publications were a great help in distributing information to the States so that all could benefit from the successes that some States were having in their construction and maintenance procedures.

An elevating grader picks up material and conveys it to a waiting truck.

In 1960, AASHO published its guide on project procedures, and in 1963, it published the first Guide Specifications for Highway Construction, which became the national standard for highway construction specifications.

During this period, there were also tremendous advances in the productivity of highway construction. One of the big advances was the development, in 1945, of self-powered equipment for onsite material stabilization, which greatly increased the productivity and control of stabilized bases and subbase courses. The rubber-tired bulldozer, first placed on the market in 1947, and the vibrating roller, introduced in 1948, proved to be very successful. In rock excavation, the new carbide insert on rock bits was a tremendous help in lengthening the life of these bits. The application of hydrostatic drive to construction equipment was also being developed. In earthwork, as well as all phases of construction as a whole, the equipment manufacturers were continuously developing heavier and more powerful units to obtain more production at less unit cost for a better quality highway.

Compaction is important in preparing a firm highway foundation. This compactor has pneumatic-tired, vibrating rollers which are particularly effective in compacting granular soils. 457