Evaluation Of Weaving Section In Freeway Interchange With Respect To Traffic Safety Based On Traffic Conflict Technique

Followed with the rapid development of highway construction in China, a lot of traffic safety problems emerged. Because of its complicated structure, interchanges often become accident-prone sections, and especially weaving segments in them are the bottleneck of traffic safety for its unique operation features. Therefore, giving safety evaluation on the highway interchanges weaving sections to improve traffic safety more efficiently is of great significance. To overcome the difficulties of shortage in accident data, this article is based on traffic conflict technique to study the forming mechanism of traffic conflict and operation characteristics is analyzed, and the traffic safety evaluation method is established.This article first consult a vast amount of literature, and the definition, configuration, influencing factors and traffic conflict mechanism were studied. Considering the research purpose and human factors, detailed survey scheme was made. The Maqun hub crossed by G42 and G36 freeway was selected as the survey object. The data of road design and traffic volume, traffic composition, speed data of different vehicle types and different positions were collected. Using the aerial video, a set of traffic conflict identification method based on trajectory tracking software Tracker was put forward. Enough samples of traffic conflicts were obtained, and the traffic conflict type, threshold value, the weight and the integrated traffic conflict index RI (comprehensive conflict risk index)/RIS (comprehensive serious conflict risk index) were determined. And then the method of comprehensive traffic conflict risk characterization suitable for highway was formed.Based on the survey data, this article analyzes the operation characteristics of traffic flow and influence factors of the operation and the relationship between the traffic conflict index, which lay a foundation for the design of the simulation experiment.Due to the objective conditions, the operation of a variety of complicated weaving configuration is realized by VISSIM simulation software. Learnt form the existing VISSIM driving parameter correction method, and combined with the traffic conflict simulation needs, "traffic flow correction-traffic conflict correction" two step calibration process is put forward, as to get optimal driving behavior parameters collection which make simulation get in line with the actual survey. By validation it is found that the simulation error decrease from 29.3% (using default parameters) to 13.1%, thus the correction effect is obvious. Combining with the analysis of relationship between various factors and the integrated traffic conflict index from the survey data, simulation experiment is designed by using the orthogonal design method, and according to the result, their relations are further analyzed.Finally the fact that lane change rate can represent disturbance of traffic flow is considered a starting point, and "road traffic conditions-lane changing times-traffic conflict index RIS" the two steps traffic conflict model is put forward. It is found that the fitting effect is good by model test.Traffic conflict data based on orthogonal simulation experiment, is used in the classification of traffic safety, and thus completed the traffic safety evaluation method based on traffic conflict technique. An application example is given, and its actual traffic accidents record to some extent shows the effectiveness of the method.