Page:America's Highways 1776–1976.djvu/395

 The AASHO Committee on Standards and its offspring, the Committee on Planning and Design Policies, were destined to have a profound effect in stabilizing highway design by recognizing and advocating the best and most economical practices of the various highway departments and in promoting the results of research efforts that were soon to be undertaken.

Another development of the decade, 1920–1930, was the initial use of aerial surveys in highway location. Mention has been made of the “topographic method” pioneered by the railroads for selecting the most suitable alinement from among a number of alternatives. Initially the topographic method did not meet with much favor among highway builders for several reasons: (1) Alinement and profile were not as critical for highways as for railroads; (2) the method was slower and more costly than the conventional or direct method; and (3) most highway projects consisted of improving an existing or established route, which might be either a trail, a well traveled artery, or something in between. The penalty for using the direct method was the production of an inferior, unsafe highway.

When aerial photography became available on a commercial scale, it offered a means of overcoming the greatest objection to the topographic method of location, namely, heavy expense in time and manpower in making field surveys and preparing maps. The highway profession was quick to recognize the potential of aerial survey methods. An example of its use described briefly in the 1927 Aircraft Yearbook:

The Bureau of Public Roads of the Department of Agriculture has used the airplane in making of mosaics to show the route of a proposed road and to ascertain over what territory the proposed road will travel. The Army Air Corps has provided the equipment and personnel, and the Bureau has provided the films and paid the cost of operation.

During the past year aerial survey has been made of a proposed new highway from Washington to Mt. Vernon, Va. The survey showed the old road as well as the territory over which the new road would have to be laid. Surveys have been made in Connecticut along the coast line, and again between Boston and New York in the vicinity of the Boston Post Road, in an endeavor to find a new automobile route to take care of the crowded travel on the old Boston Post Road.

The article concluded that the saving in time and money on these and other projects was very satisfactory, and future use of this means of mapping and surveying was contemplated. This was a very conservative prediction.

A typical main highway of the early 1920’s. The major defects are the 16-foot concrete pavement width, narrow and poorly maintained shoulders, and the encroachment of utility poles. 389