Cost-Effective Reporting of Travel on Local Roads

Abstract

The purpose of the Highway Performance Monitoring System of the Rural and Local Roads Reporting Project was to develop a more accurate, yet cost-effective, methodology for estimating vehicle miles traveled (VMT) on urban local roads, rural local roads, and rural minor collectors throughout Florida. A review of Florida's existing methodology, methodologies of five “peer” states, and available research was completed to develop specific evaluation criteria that could then be applied to several conceptual methodologies developed from the synthesis of information. The project team selected a preferred VMT estimation methodology that used census data and random sampling. The preferred methodology makes use of available census data and an intuitive correlation between travel and population density, job density, and roadway density, while it eliminates the dependence on volume groups that is part of FHWA's methodology for higher-order roadways. The density factors are used to group similar zip code tabulation areas (ZCTAs) into subregions to allow random samples taken in one subregion to represent similar ZCTAs statewide on the basis of any or all the following: population, job, and roadway density. A minimum number of random samples is selected to retain statistical validity while minimizing costs to conduct traffic counts. The methodology is flexible enough to allow adjustments (e.g., restratification based on indicators such as coefficients of variation) that improve the quality of the results from year to year. Implementing a test case of the methodology to determine real-world applicability is the next logical step in the research process.