USING GPS FOR MEASURING HOUSEHOLD TRAVEL IN PRIVATE VEHICLES

Personal travel and how it changes is of continuing concern to transportation planners and policy makers. Information about daily travel patterns are generally captured using self-reported information using a written diary and telephone retrieval. This project developed a small, user-friendly, mailable unit including a Global Positioning System (GPS) receiver to capture vehicle-based, daily travel information. The unit is a Sony MagicLink (registered trademark) 2000, a Personal Digital Assistant (PDA) with a backlit screen, weighing about 1.5 lb (0.68 kg). A Garmin (registered trademark) GPS antenna/receiver is attached through the PDA serial port. Finally, a power cord connects the data collection unit to the vehicle electrical system via the vehicle cigarette lighter. The vehicle driver uses a touch-screen menu to enter variables such as trip purpose and vehicle occupancy, but other data such as date, start time, end time, and vehicle position (latitude and longitude) are collected automatically at frequent intervals. Finally, after mail-back return of the units, the data are processed using a geographic information system (GIS) to include calculated results such as travel speed, trip distance, and trip time by road classification and other variables. This method of data collection has two potential benefits: (1) improving the quality of travel behavior data, and (2) reducing respondent burden, for example, interview time on the telephone for reporting travel. Using GPS technology, while increasing privacy concerns, is expected to improve overall survey responses in travel behavior studies. The proof-of-concept field test, conducted September through December 1996, placed the units in 100 household vehicles in Lexington, Kentucky. Respondents were asked to use the unit to record personal travel information for six days. Respondents were also asked to participate in a post-usage telephone interview that included a recall interview about travel information for one day of machine usage and also captured information on ease of use and the respondent's attitudes and reactions to this data collection technique. Technical issues related to hardware, software, field implementation, and analysis and comparison of results between self-reported travel and machine-recorded travel are provided.