In China, safety evaluation for highway safety performance has been based on traffic crash analysis or traffic conflict analysis. However, it is very difficult and time consuming to obtain historical crash data or traffic conflict data, mainly due to the lack of routine procedures and strict requirements for traffic data managements in China. A research project was performed to develop a procedure for highway intersection safety performance evaluation with limited requirements for field crash and traffic data. In that research, the concept of level of safety service was introduced and corresponding models were developed. The variables included in the models for level of safety service are intersection geometrics, traffic conditions, and roadway and environmental conditions. Conceptually, evaluation models under idea conditions are only based on intersection conflict points (not number of conflicts) between motorized traffic, motorized traffic and non-motorized traffic, and motorized traffic and pedestrians. The variables related to geometrics and traffic control conditions under prevailing conditions are used to adjust the level of safety service under idea conditions so that level of safety service under prevailing conditions can be obtained. Field data and questionnaire survey were conducted to obtain model parameters and expert panel field evaluations were performed to validate the performance of these models. Similar to traffic level of service, six levels (from A to F) are used to evaluate intersection safety performance with Level A indicating the best safety service and F representing failure of safety performance of the intersection.
Abstract