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22 volved. The relation of each section of the routes with respect to all possibly competing highways was carefully studied and a judgment was formed as to the part of the known traffic using such competing roads that could be attracted to the new facility. Mathematical exactness in such judgments was an impossibility; and to avoid underestimation there was studied effort to maintain a liberal bias. The resulting estimates, therefore, are believed to represent the maximum traffic that could reasonably be expected to make use of the proposed facilities if operated as free limited-access routes.

Having considered every section of the proposed routes from this point of view, the next step was to convert the estimates made upon the assumption of free use into estimates of the probable toll-paying traffic.

A consideration of the ability of people to pay tolls, as indicated by the distribution of automobile owners by income groups, and further consideration of actual fees which would be charged for specific trips over various sections of the routes, led to the conclusion that not more than about one-third of the vehicles that might use a typical free road of limited access could be regarded as potential traffic for the same road operated as a toll facility.

The general estimate of one-third as the proportion of users of a free limited-access facility who would use a similar toll facility and estimates of toll-road traffic based thereon were submitted to responsible highway authorities of all the States with a request that they comment upon the reasonableness of the assumptions and the resultant traffic estimates. In arriving at the final estimates of traffic likely to use the proposed routes, if operated as toll facilities, comments received from the State officials were considered together with a firsthand review of the particular attractiveness of each section of the routes and of the ability of the potential users in each section of the country to pay a toll of 1 cent per mile for passenger cars.

On the basis of this further study various factors, ranging from 0.167 to 0.40, were decided upon for application to the estimated free-facility traffic to convert it to an estimate of traffic on the toll facility. In densely populated areas, where highway congestion in considerable degree has already been experienced and where there are relatively large numbers of potential users who are able to pay tolls, factors as high as 0.40 were used. This value was used, for example, on the section of route 1 between New York City and central Connecticut. In sparsely populated areas, where thus far little or no congestion has been experienced and existing modern highways afford excellent service, factors in the lower range were used. For example, a factor of 0.20 was used for the section of route 4 between Evanston, Wyo., and Rock Springs, Wyo.

The estimates thus made of the traffic that would have used the various sections of the selected routes, if operated as toll facilities in