University of California Transportation Center

While characteristics of daily travel behavior have been determined from analyses of the reconstructed household travel behavior recorded in travel diaries, such reconstructions are subject to criticisms. Respondents in a survey may lie or falsely recall information about destinations, times of travel, trip purpose, trip destination and other critical characteristics, such as under-reporting of short trips and the number of stops in a trip chain (Brog, et al., 1982; Purvis, 1990). In 1997 the Department of Transportation carried out a one-week study in Lexington, Kentucky in which the cars of 100 households were equipped with GPS and in-car computers. Every stop was logged by the GPS receiver, and the purpose of the stop was recorded in real time on an in-car computer. The final report of the study gave descriptions of travel behavior but performed little analysis on the data so collected. Although the new GPS-involved data collection methodology is not expected to replace the traditional data collection method in behavioral science within a short period of time, it does provide a more robust alternative for defining personal travel than the current methods. After being provided with a CD data record of all the transactions by DOT, a variety of analytical techniques and methods were used on the GPS-collected survey data.