Roads carrying less than an average of 1,000 vehicles per day average 20 feet in surface width, or 4 feet less than the width recommended for interregional highways of such traffic volume. The choice of surface type for these roads is generally consistent with the traffic served. The frequencies of occurrence of sharp curves, steep grades, and consequent restricted sight distances as a group average less for these most lightly traveled roads than for most of the heavier traffic-volume groups; and the existing right-of-way provided is more nearly adequate.
The close approach to adequacy existing on these lightly traveled roads results principally from three circumstances. First, many of the routes included are in sections of the country where most roads follow the straight lines of land sections established by the Government; second, many are located in sparsely settled rural areas of easy topography where the obtainment of reasonably satisfactory alinement and wide right-of-way has been a comparatively simple matter; and third, they generally received their initial improvement at a later date than the more heavily traveled roads and benefited in that improvement by more modern standards of design.
The relative adequacy of these lightly traveled sections, however, only serves to throw into stronger relief the grave inadequacy of the more heavily traveled sections, especially in right-of-way and pavement width and sight distance.
