Diagnostic Approach for Safety Performance Evaluation and Improvements of Highway Intersection

Highway safety is one of the most important issues in transportation. Intersections are the locations with higher traffic crashes compared with other highway locations. To evaluate or assess the safety performance of an intersection, traffic crash analysis is the most popular method and has been used for a long history. However, traffic crash analysis is based on a lot of crash data which needs to be accumulated through a long time period. Besides, sometimes, traffic crashes randomly happen with the impacts of human driving behavior. Therefore, without sufficient data and crash history, traffic crash analysis may not give an overall evaluation for the intersection safety performance. This paper introduces an approach to evaluate highway intersection safety performance. This approach is fully based on the existing conditions of the intersection, including geometrics, channelization, sight distance, pavement surface conditions, traffic control devices, traffic signal timing, and phasing, etc. The non-accident based approach is based on field survey to the conditions mentioned before. The approach will also result in a safety index to indicate the safety performance degree of the intersection. Meanwhile, corresponding countermeasures are ranked and recommended based on the cost-benefit analysis. The content of this paper is based on the research results from a part of a research project (entitled i°Safety Design of Highway Intersectionsi±) sponsored by China Department of Transportation. In this paper, the approach (called diagnostic approach) is practically applied to evaluate the safety performance of some intersections in Shan Dong Province and Jiang Su Province. Results from the real application indicate that the approach has good applicability and can be used by field safety engineers in real application. In addition, the approach is implemented into software with friend operational interface.