Methodology for Estimating Vehicle Miles Traveled for Commercial Motor Vehicles at the State Level

Abstract

Described is one specific effort to better estimate commercial motor vehicle-related exposure at the state level in order to better determine commercial motor vehicle-related crash rates for state and federal programs. Limitations in the crash and exposure data affect the Federal Motor Carrier Safety Administration and a state’s ability to plan and assess operations and conduct ongoing analyses of program effectiveness. One important limitation has been the lack of reliable estimates of commercial motor vehicle exposure data at the state level. Exposure data, for the purpose of this report, are defined as the number of truck and bus vehicle miles traveled (VMT). Described is the methodology that was developed to calculate adjusted state VMT for commercial vehicles; results are presented for 1999 and 2000. The results support estimation of crash involvement rates for each state and provide exposure data for other analytical studies. The methodology to calculate adjusted state VMT for commercial motor vehicles has resulted in improved information resources in support of all crash analyses. The adjusted state VMT for commercial vehicles supports measurement of program effectiveness and development of countermeasures to promote motor carrier safety. The adjusted state VMT for commercial motor vehicles methodology and the commercial vehicle fatal-crash involvement rate reports enable state and federal agencies to better focus their safety programs and enforcement resources.