Distinguishing between incident congestion and recurrent congestion : a proposed logic.

A key element of freeway traffic management systems (FTMSs) is the detection of incidents. The problem with most incident-detection algorithms is that they do not detect incidents as such; rather they detect congestion, whether it is caused by an incident (incident congestion) or by a recurrent bottleneck situation (recurrent congestion). The purpose of this paper is to present a logic for distinguishing between incident congestion and recurrent congestion. The logic uses 30-sec volume and occupancy summaries at each FTMS detector station to classify traffic operations into one of four states. If congestion is detected at one detector station, the cause of this congestion is defined on the basis of the traffic state at the downstream detector station. Results from a preliminary evaluation of the proposed logic are promising.