TESTING FOR SIGNIFICANT INDUCED TRIP MAKING AND TRAVEL IN PROVIDENCE, RHODE ISLAND

The research reported in this paper was conducted in order to determine whether or not increased highway supply causes increased travel or trip making or both. In order to make this determination, data from origin-destination travel surveys conducted by the Rhode Island Department of Transportation in Providence for the years 1961 (before construction of I-95) and 1971 (after I-95) were used. For each year the origin-destination survey data from the Providence area were divided into two groups--samples representing households inside the I-95 corridor and samples representing those outside it. For the resulting four groups of households, cross-classification matrixes were developed using household size and auto ownership as independent variables; the dependent variables were vehicle-kilometers of travel (VKMT) per household, vehicle-hours of travel (VHT) per household, and auto driver trips per household. The comparison of the resulting matrixes revealed that the highway did not increase trips or VHT, but it did increase VKMT. This allows the tentative conclusion that travelers increase their VKMT until they use up a given amount of travel time. This conclusion supports the standard system-insensitive approach to trip generation as well as the use of travel time as an impedance in trip distribution. /Authors/