Traffic Delay Studies at Signalized Intersections with Global Positioning System Devices

Traffic delays at signalized intersections are difficult to measure manually. This paper presents methods for applying global positioning system (GPS) devices to study these delays. In this study, vehicle positioning data were recorded with a GPS device at selected intersections on several roadway sections in Indiana. At the same time, stopped-time delays were measured manually by observers at some of the intersections following conventional procedures, so that stopped-time delays measured both by GPS and manually by observers could be compared. Findings showed that the GPS measurements provided the same accuracy as manually measured stopped-time delays with much less time and labor intensiveness. These results indicate that GPS can be an effective tool for traffic delay measurements and analyses.