Freeway Database Storage and Loop Detector Validity

摘要

The research project developed a data error detection algorithm for the Washington State Department of Transportation's electronic surveillance system, which is located at the Traffic Systems Management Center in Seattle. The algorithm compares 20-second volumes and 20-second volume/occupancy ratios with threshold values to determine the reliability of detector data. The algorithm will operate on the central computer system for the electronic surveillance system. Tests of the algorithm proved it to be very successful at detecting data errors caused by short pulses (hanging off) from detectors, chattering detectors, and intermittent malfunctions of detectors. The algorithm did not detect errors caused by long pulses (hanging on) from detectors. The false alarm rate was very low (24 false alarms out of approximately 3,500 observations).