Investigation of an empirical methodology for linking value of time with census tract median income

Abstract

This research examines a new methodology for prospectively estimating the willingness of travelers to use a toll road by combining travel time saved with the income of the prospective customer base. The purpose of the research is to facilitate network level planning by allowing some reasonable predictions of acceptable toll rates from readily available data and estimation techniques. Methods of estimating user benefit resulted in simulated distributions of value of user time. Values of time are linked to census tract income data for the user population to produce value of time as a percentage of income as an indicator. As relevant literature acknowledges the tendency toward increased toll road usage at higher income levels, it is hypothesized that linking estimates of value of time directly to household income would produce a more useful indicator of the travel market than do conventional indicators. Techniques for prospectively estimating the travelshed of a toll road are compared with the actual travelshed, as reflected in user home census tracts, as a means of evaluating the efficacy of those techniques in estimating the market area of a prospective toll road. Results show that considering value of time as a percentage of census tract median income provides an improved portrayal of the toll road market, as usage of the toll road increases with increasing income. Using census tract median income as the income parameter has shortcomings, in that it produces anomalous results at very low population levels. Of the two methods of estimating the travelshed, the visual estimation approach was not satisfactory, leaving the analyst to use select link analyses instead.