Developing a Statewide Travel Demand Model from a Person-Based Time Series Household Survey

Balancing the funding needs of data collection and model development is a recurring problem for state departments of transportation and metropolitan planning organizations throughout the country. To address this problem, the Delaware Department of Transportation (DelDOT) and the University of Delaware have developed an innovative and cost-effective person-based time series household survey that has been conducted annually since 1995. The survey diverges from traditional household travel diary surveys in that it is a telephone survey that collects detailed demographic information on all household members but collects trip information from only one randomly selected household member. While the survey costs between 20% and 50% less than a typical household travel diary survey and greatly reduces nonresponse bias, this survey poses two complications. The first is that household trip generation rates must be synthesized if trip productions are to be estimated on the basis of household cross-classification tables; the second is that the data must be normalized to represent a data set for a single year. A description is provided of the procedure by which this survey was used to perform a major update of DelDOT's statewide travel demand model in 2003. The survey was relied on to provide key information in the first three steps of the four-step travel demand modeling process. This survey method has the potential for widespread application, particularly for microsimulation models, which would not require the household synthesis step.