Spatiotemporal Analysis of Traffic Congestion Caused by Rubbernecking at Freeway Accidents

In this paper, we present a well-specified analytical methodology for estimating capacity reduction that is attributable to accidents in the opposite direction of accident-the condition whereby drivers in the opposite direction of an accident, by virtue of their curiosity, tend to be distracted by the accident. The methodology is based on a binary integer programming formulation that is used to identify the spatiotemporal region that is affected by the influence of the accident. Thresholds measured against control sample readings from inductance loop detectors are used to determine the patterns and magnitudes of the delay. A key feature of the methodology is its ability to separate nonrecurrent delay from any recurrent delay that is present on the road at the time and place of a reported accident, to estimate the contribution of nonrecurrent delay caused by the specific accident. A case study that is based on historical inductance loop detector data from six major freeways in Orange County, California, is presented. Potential factors contributing to delay, including accident characteristics, geometric characteristics, environmental condition, traffic characteristics, and congestion characteristics, are analyzed for their effects by using the semiparametric Cox proportional-hazards model.