Evaluation of the SCATS Adaptive Traffic Signal System in Oakland County
William C. Taylor, Department of Civil and Environmental Engineering
Oakland County, Michigan was selected for a Federal ITS Demonstration Project on the effect of adaptive traffic signals on system performance. This study, which has been ongoing for nearly ten years, considers both the delay and the safety impacts of the system.
Data from detectors using Video Image Processing technology provide information on traffic movement at over 500 signalized intersections in the country. This information is transmitted to a Traffic Control Center located in the Road Commission for Oakland County offices, and is used to vary the cycle length, phase plan and signal offset at these intersections to minimize delay. The processed video image data, data on the signal response (changes in cycle lengths, phasing and offsets) and travel time and delay data collected in the field are used to conduct the evaluation of the system. The safety impact is evaluated by analyzing the crash data before and after the system was implemented.
The results have shown that the adaptive signals are effective in reducing delay on major corridors throughout the network. The percentage reduction in delay is a function of the corridor attributes and the time of day, with the most significant reductions occurring in the non-peak periods when the re-allocation of green time is possible.
Department of Civil and Environmental Engineering
3546 Engineering Building
Michigan State University
East Lansing, MI 48824-1226