Incident detection using vehicle-based and fixed-location surveillance

Many recent intelligent transportation systems (ITS) deployments feature vehicle probes as prominent sources of information about traffic conditions in addition to, or in place of, fixed-location measurement devices such as inductive loop detectors. Several other technologies now used for traffic surveillance and deployed in fixed locations are reviewed and found to provide the same kinds of information as more complex probe vehicle systems. Recent experience with both fixed location and vehicle-based incident detection systems is summarized. Several incident detection algorithms calibrated with both fixed-location and vehicle-based traffic measurements from a simulation of a signalized arterial street are introduced. The performance of these algorithms, some of which use data from only one source while others use data from both sources, is compared. While the fixed-location measurements appear to be superior to the probe reports for detecting incidents when used alone, different incidents are detected by their respective algorithms. Algorithms using both sources of data perform substantially better than either single-source algorithm, indicating that there is value in collecting information using both methods.