USING PROBE VEHICLE SPEED DATA TO ASSESS THE ACCURACY AND RELIABILITY OF THE TRAFFIC MONITORING STATIONS ON FREEWAYS

摘要

Freeway performance measures are extracted from Traffic Monitoring Stations which gather traffic volume and speed data. Reported freeway speeds are usually aggregated over a period of 20 or 30-second or 1, 5, or 15-minute by traffic agencies. This paper evaluates how various aggregation intervals impact accuracy and reliability of the reported freeway loop detector speeds and determines the optimal aggregation interval. The study compares speeds collected by probe vehicles equipped with Global Positioning System versus aggregated detector speeds. Results indicate the need to archive 20-second detector data in addition to current 15- minute data archiving by the Utah Department of Transportation.