Page:Interregional Highways.pdf/65

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From the resulting graph it was assumed that a maximum value of average daily traffic might have been attained in the 29,300-mile system. If this value could be exceeded it was conjectured that a maximum value might be obtained by a properly selected system of either 36,000 or 33,000 miles approximately, the mileages represented by other intersections of the straight lines of the graph.

Accordingly, a 36,000-mile system was formed by adding to the routes included in the 29,300-mile system, certain routes designed to connect relatively important cities not reached by the smaller system and by eliminating a few of the less important routes. The resulting system is shown by the solid lines of figure 25, the heavier lines representing the added routes. The dotted lines in this figure represent the routes of the 29,300-mile system that were omitted from the larger system. As shown in the middle section of table 13, this 36,000-mile system proved to have an average daily traffic volume on its rural sections of 2,580 vehicles—slightly less than the value for the 29,300-mile system and also less than the value indicated by the 36,000-mile intersection point in the graph, as shown by the lower solid dot.