An analysis on the impact of rubbernecking on urban freeway traffic.

An incident influences traffic not only in the incident direction but also in the opposite direction. There has been research on the influence of incidents on the traffic in the incident direction. However, research relating to the influence on the opposite direction of traffic is rare. Previous research has shown that congestion due to incidents accounts for 60% of the total congestion on a freeway system. These incidents cause the freeway system to operate inefficiently. By determining which variables contribute to the “non-recurrent” congestion and also the impact on traffic, mitigation techniques may be applied to minimize these effects. In this study the impact of incidents on the traffic in the opposite direction was investigated with focus on rubbernecking likelihood, delay, and capacity reduction. To achieve this study certain objectives were met. First, a database consisting of incident information, traffic and other related variables was developed. The next step was to determine whether the rubbernecking impact on the opposite direction traffic was significant. Factors that influence the impacts of rubbernecking likelihood were identified. Recommendations of effective countermeasures were developed to possibly reduce rubbernecking impacts. Traffic data was investigated while congestion delay as well as capacity reduction calculations were performed. This study is the first attempt to evaluate the rubbernecking impact of accidents on traffic in the opposite direction based on archived traffic and accident data.