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Rh in these same States approximately 1,155 miles of rural roads that were improved with pavements more than two lanes wide. On the basis of pavement width only, therefore, there may be in these 12 States some 3,000 miles of rural roads on which the traffic has reached such a volume as to suggest the possible need of greater pavement width than has been provided.

However, as suggested by the traffic volume profile on plate 56, it is probable that this entire mileage is located within a relatively short distance of the cities of the 12 States. The profile shows uniformly a rapid drop in the traffic with increasing distance from the cities, and generally quite moderate traffic volumes beyond the immediate environs of the cities.

Not only do the findings of the planning surveys show that beyond the vicinity of the cities there is no great mileage of the existing main rural highways that requires increase in the number of its lanes, but they also show the existence of a number of other conditions on a considerable part of the mileage that urgently require correction. Plate 56 shows graphically the nature and prevalence of these unsatisfactory conditions on the existing highway from Philadelphia to San Francisco.

Distances along the highways are represented in this graph to a greatly condensed horizontal scale. The character of the highway pavement or surface at all points is represented by the shading or hatching within the broad bands extending across the diagram; and information concerning nine other important conditions in relation to each mile of the highway is presented by various plottings to six conveniently enlarged vertical scales.

The width of the pavement or surface on each mile is represented to the indicated scale by the width of the hatched lower band. To the same scale the distance between the horizontal lines immediately adjacent to the hatched bands represents the width of right-of-way at all points.