The Dirty Job Of Truck Movement Data Gathering: An Evaluation of Intercept Surveys

Many states have limited information on truck trips, their origins and destinations, routes traveled and commodities carried. The overall goal of this study was to identify a reliable data collection method capable of generating specific detail useful to Oregon Department of Transportation’s modeling and freight planning needs for data on truck movements at the metropolitan level. This report looks specifically at the use of interceptor surveys at different land use locations. Roadside interviews were conducted on an interstate highway, a port facility and a warehouse/distribution center. Results indicate that data captured at roadside interview locations do provide excellent trip detail for inter-regional movements (state and interstate highway locations) and also very good trip detail for intra- regional freight movements (warehouse / distribution center locations). It was found that the capture rate (number of vehicles sampled out of the total volume) is dependent upon available parking and survey personnel relative to the total truck traffic volume and undoubtedly will vary by roadside interview site. All three types of roadside interviews produced high response rates related to vehicle and trailer, carrier identification, route, and facility. Roadside interviews at the warehouse/distribution center and interstate highway weigh station provided high response rates related to commodity type, while the preponderance of container traffic at the port facility limited responses on payload information. Obtaining specific street addresses and zip codes for trip origin and destination is very difficult for all types of roadside interviews, but the best responses were from warehouse/distribution centers. Specific findings and analyses will be presented in the paper. Implications for costs and applicability are drawn.