Research On Setting Method Of Traffic Guide Signs On Expressway Based On Fault-Tolerant Concept

People always go wrong, which is inevitable in the process of driving. The improper operation, negligence and carelessness condition of drivers caused by unreasonable setting of traffic guide signs is one of common traffic accident causes. The optimal setting of traffic guide signs on expressway based on fault-tolerant concept is a reflection of humanization and tolerance and an important way of improving movement efficiency and ensuring traffic safety.This study used the fault-tolerant theory in computer field for reference and applied fault-tolerant concept to road traffic system. The principles and exsiting problems of traffic guide signs setting on expressway were discussed, then the necessity of applying fault-tolerant concept to set traffic guide signs on expressway was analyzed.The key point of whether traffic guide signs on expressway have fault tolerance is that their visibility are good or not. The study took visual cognition time and missed reading rate of rout-guiding information to characterize the visibility of traffic guide signs on expressway quantitatively. The impacts of information quantity of traffic guide signs and vehicle speed on visual cognition time and missed reading rate of rout-guiding information were studied respectively to find the overload threshold of traffic guide sign information was studied and analyze the reasons and rate of missed reading by indoor and outdoor experiments. The specific setting requirements were given to improve fault-tolerant performance of traffic guide signs on expressway and then serve firstly for drivers who are not familiar with road network.Through studying single sign's visibility, the setting method of traffic guide signs on expressway was studied by using redundancy techonology on the purpose of decreasing the missed reading rate. Based on the interactive relationship between redundancy technology and fault-tolerant ability of a system, the redundant degree and their space of traffic guide signs setting were studied and the method of determining redundant degree was given. Besides, combined with the setting location of guide signs and the selecting rules of rout-guiding information, the setting methods of traffic guide signs on expressway based on redundancy technology were put forward. Moreover, this study gave a setting example based on redundancy technology in Beijing.This study established the evaluation index system of fault-tolerant performance on traffic guide signs setting from the angle of man-machine engineering, and applied AHP to determine the weight of each index. The fuzzy comprehensive evaluation method was selected to establish a comprehensive evaluation model. Furthermore, the study took an expressway in Harbin as an evaluation example so as to make a fuzzy comprehensive evaluation on its fault-tolerant performance. Finally, according to weak sections which were reflected in the evaluation example, the improvement measures of traffic guide signs on expressway based on fault-tolerant concept were proposed.