Safety Evaluation Method On ETC System

ETC(Electronic Toll Collection) system which is a mature subsystem of ITS(Intelligent Transportation System) not only offers solution to the problems caused by toll collection such as congestion, delay, energy waste and environment pollution but also lays the foundation for the implementation of the following policies and correlative technologies(such as Weigh-in-motion and Variable pricing). However, the safety benefits of ETC system are not clear by far, to say nothing of a whole system of ETC safety evaluation.The main purpose of this paper is to present the evaluation method of ETC and, moreover, build its safety evaluation framework. Based on the methodologies used to evaluate the safety impacts of other traffic facilities, a direct evaluation approach based on accidents and an indirect evaluation approach based on traffic conflicts are chosen as preparatory methods evaluating the safety impacts of ETC. These two approaches have their own characteristic and applying conditions so it should be in accordance with the real situation choosing the direct or/and indirect approach.After summarizing the safety factors of toll plaza and analyzing the safety impacts of ETC, it begins to establish the safety evaluation system of ETC. First of all, the direct approach is discussed which includes small-sample evaluation approach and great-sample evaluation approach according to the sample size. Then the field data collection procedure is presented after describing the definition and types of conflicts in toll plaza and conflict identification. The safety impacts of ETC system can be achieved by comparing the numbers of various types of sever conflicts before and after the implemention of ETC. Though the direct approach and the indirect approach is not brought into effect thoroughly because of the limitation of the data in the field, it is still helpful for us to understand better the applying conditions and evaluation procedures of the two approaches according to the demonstrating projects which are respectively appended following with the introduction of these two approaches.