Determining trip information using GPS data

Abstract

With the development of lightweight, high sensitivity Global Positioning System (GPS) devices, there has been increasing interest in their use as a means to measure people’s travel for travel surveys. Data-logging enables a person’s position, speed, and heading to be recorded on a second by second basis. GPS devices cannot, however, collect data on the mode or the purpose of travel, both of which are frequently required for transport planning purposes. This paper describes a set of heuristic rules developed by the authors for determining both the mode of travel and the purpose of trips recorded on GPS devices. This processing utilises comprehensive GIS databases for the areas where the GPS surveys have been conducted. These include information on all public transport routes in the region of interest. The rules developed consider the average, maximum and minimum speeds when determining mode of transport. They also use information about the transport network and the availability of bicycles and cars to the survey participants. Data-cleaning procedures are incorporated to eliminate erroneous information obtained from the devices themselves. To determine the purpose of a trip, it is necessary to have full land use records for all locations in the survey area. The addresses of all workplaces, schools, and most frequently used grocery stores visited by household members are also collected. Our procedure checks trip origins and destinations against these locations, and also the amount of time spent at the destination. We have applied our procedure to data obtained from a survey in Adelaide. The procedure gives results which are comparable to those obtained using a more burdensome travel diary.