Estimation of detour rate on freeway during non-recurrent congestions

Traffic incidents have long been recognized as the main contributor to congestion in highway networks. Thus, contending with non-recurrent congestion has been a priority task for most highway agencies over the past decades. Under most incident scenarios, if proper diversion plans can be implemented in time, motorists can circumvent the congested segments and best use the available corridor capacity. To tackle this vital operational issue, transportation professionals have proposed a variety of advanced diversion control and route guidance strategies to optimally balance the volumes between the freeway and the arterial. In such a system, reliably estimated detour rates based on the predicted incident duration and queue length plays a key role in selection of strategies for mitigating incident-related delays and impacts. The ATTAP team is developing reliable models for estimating the detouring volume, with or without available ramp sensors. The results from those models will assist traffic agencies in making proper decisions regarding control and operation strategies.