Can using global positioning system (GPS) improve trip reporting?

In the United States, information about daily travel patterns is generally captured using self-reported information using a written diary and telephon e retrieval (or mail-back of diary forms). Problems with these methods incl ude lack of reporting for short trips, poor data quality on travel start an d end times, total trip times and destination locations. This project combined a hand-held computer (Personal Digital Assistant or P DA) with a Global Positioning System (GPS) receiver to capture vehicle-base d, daily travel information. The vehicle driver uses a menu to enter variab les such as trip purpose and vehicle occupancy, but other data such as date , start time, end time, and vehicle position (latitude and longitude) are c ollected automatically at frequent intervals. The field test was conducted in Lexington, Kentucky in fall, 1996, with 100 households to use the equipment for six days. Respondents also completed a telephone survey for one day of travel (attempted for day 5). The field te st was a test of equipment and willingness of the general public to partici pate, rather than to obtain a statistically valid travel behavior dataset f or the Lexington area. One improvement to the hardware would be for the equ ipment to turn on automatically. There are limitations to the dataset and a nalyses that are discussed where appropriate. Although the dataset is small , this paper compares the results of the machine-recorded trips to self-rep orted trips captured by telephone interview. Self-reported distances are much longer than distances recorded by the PDA/ GPS. A recalled distance of 10 miles was, on average, only 6.5 miles when t he GPS points are matched to a positionally accurate base file. Similarly, recalled times generally exceed median measured values, but the differences are much smaller than for distances. Respondents reported that data entry of 1 min at the beginning of each trip over the six-day survey period was n ot burdensome. Recommendations for improving the hardware and software for conducting othe r travel surveys using GPS, and improving the utility of travel data collec ted using GPS are provided. One of the benefits of incorporating a GPS devi ce into the survey process was the ability to collect information on route choice and travel speed. However, this paper does not address these topics. Published by Elsevier Science Ltd.