Page:America's Highways 1776–1976.djvu/456

 by the various States. The information was passed on to the other States for their mutual benefit. All of the construction work was supervised and inspected by State engineers. Public roads field engineers made periodic inspections to assure compliance with the approved PS&E. All changes in the plans or extra work that became necessary during the life of contracts were reviewed by BPR. A final review and inspection of all engineering features of the completed project was made by BPR before payment of the final reimbursement for the Federal share of the work done.

This road was surfaced using the penetration method. Aggregate was spread on the roadbed first and the bitumen poured on top.

In the early twenties, the average length of Federal-aid projects was just over 5 miles, and the average cost per project was roughly $85,000. The average cost per mile was about $17,000. Of the roads completed during this period, about 25 percent were paved, and the rest were surfaced with gravel, sand-clay, or other select material. On the paved roads, about 65 percent was spent on surfacing, 20 percent on grading and nearly 15 percent on structures. The Federal share of these projects was approximately 50 percent.

The unit prices for the various items of road construction, such as excavation, concrete pavement and structural concrete, were, in general, more expensive in the twenties than they were in the thirties. Of course, this was partly due to the Depression of the 1930’s, but it was also due to the development of equipment to replace more expensive hand methods. This enabled roadbuilders to move more earth and pour more concrete for the same amount of money in the thirties than they could in the twenties.

The cost data were compiled on all projects and forwarded to the BPR Washington office for analysis to determine the trends in highway construction cost for various types of construction. This information has proven to be of such general interest through the years that it has become the basis of a quarterly index, showing the relative movement of highway construction costs over a period of years.

During the early twenties, important advances and experiments were made in all phases of management techniques and standardization development in the construction and maintenance of roadways. This work by the BPR and private organizations increased the capability to produce cheaper, more efficient, quality roads.

A steam roller rolls a second coat of bitumen with chips on a macadam street in 1922. First a coat of bitumen was spread, then a layer of large stones, followed by another coat of bitumen, and, finally, a layer of smaller stones to fill in the voids. 450