The existing routes which would be improved by the proposed system are shown by the traffic map, plate 59, to be in each locality the most heavily traveled, as a whole, of all routes in the numbered United States Highway System.
Compared with the selected toll road system, conforming to the congressional definition, this suggested Primary Highway System of the United States, is nearly twice as large, made so by the essential inclusion of all routes of primary importance and interregional utility, not possible within the limits set by the act.
Improved as a system of public roads along lines chosen to facilitate the important traffic awaiting its service, it will attract traffic and generate new activity, in contradistinction to the traffic-repelling tendency of the proposed toll-road system.
With the aid of all State highway departments the significant conditions of all present highways approximating the lines of the direct system, including the average daily volume of traffic in 1937 on all such highways, have been ascertained and diagrammatically recorded for further study on straight-line diagrams, of which that reproduced in plate 56 is a typical sample. No such precise and acceptance-compelling information has ever before been available or possible of assembly with reference to a projected highway plan of comparable magnitude. Either already compiled or quickly available, there are ascertained facts to answer whatever questions may be asked as to the need for, and manner of making, the important improvements suggested.
The existing routes most nearly conforming to the direct routes suggested now serve somewhat less than 10 percent of the total vehicle-mileage on all rural highways. The suggested more direct routes would lose little of this traffic, and attract from other highways considerably more than they would lose, besides generating a large amount of new movement. Although in mileage they would represent as a system less than 1 percent of the total rural highway mileage of the country, they would unquestionably accommodate at least 12.5 percent of the total rural vehicle-mileage. This may be compared with the utilization estimated for the selected toll-road system which amounts to about 1.2 percent of the total rural vehicle-mileage.
These roads would directly substitute for substantially all of the most heavily traveled of present rural routes and would subtract heavily from lesser traffic streams now following other roads. By providing ample capacity and every safety device known to modern highway engineering, the construction of these roads would effect a greater reduction in the highway accident rate than could be made by an equivalent sum spent for highways in any other way.
Wherever it may be done, consistent with the purpose of direct routing and other essential considerations, the suggested routes should follow the alinement of, and incorporate the improvement of, existing highways. Reasonably direct connection between the major cities along their general lines should be the controlling thought in choosing revised location. Deviation from such direct lines should not go far for any purpose, and should be accepted in limited degree only to pick up the largest intermediate towns.
The routes should enter and traverse all large cities by means of facilities adequately designed to promote free movement of. traffic to and through the center of the city. At large cities, wherever
