Determining the start time of an incident from real time sensors

Travel time information is important for Advanced Traveler Information Systems (ATIS) applications. People traveling on urban freeways are interested in knowing how long it will take them to reach their destinations, especially under bottlenecks, congestion and incident conditions. Though many advances have been made in the field of traffic engineering and ITS applications, there is a lack of practical travel time estimation procedures for ATIS applications under incident conditions. The purpose of this research is to develop an algorithm for travel time estimation on urban freeways for ATIS applications under incident conditions. The algorithm is based on point estimates of traffic variables obtained from vehicle detectors. The focus of this paper is on determining the start time of an incident, which is a crucial input to determining the delays and consequently the travel times encountered by the travelers based on the sensors input.