Research On The Redundancy Setting Method Of Urban Trunk Road Ttaffic Signs Considering Vehicle Occlusion

As an important infrastructure in urban road system,traffic signs mainly convey traffic information to road participants through symbols and words.However,traffic signs belong to road ancillary facilities and have not been given the necessary attention like the main projects.Traffic signs are set blindly in accordance with national standards,while ignoring the impact of traffic flow on the setting of traffic signs in urban trunk roads,such as traffic signs are blocked by large vehicles.The purpose of this paper is to analyze the relationship between the failure probability of traffic signs and the influencing factors,study the redundancy setting method of traffic signs,and provide scientific suggestions for reducing the failure probability of traffic signs,so as to improve the safety and efficiency of drivers.According to the main layout forms and characteristics of traffic signs,this paper chooses side column and cantilever traffic signs as the research objects.This paper studies the process of drivers' recognition of traffic signs,analyzes two kinds of traffic sign occlusion forms:side pillar type and cantilever type.The relationship between occlusion failure and occlusion of traffic signs is finally identified.The occlusion time model is introduced for the defect of occlusion space model.Based on the geometric relationship of small cars,large cars and traffic signs on the visual section and the limitation of VISSIM software,the starting counting condition,termination counting condition and occlusion judgment condition of traffic sign occlusion are studied.According to the setting criteria of traffic signs and the process of driver's recognition of traffic signs,the simulation section length,simulation step length and other related parameters are determined.Several data of simulation time,vehicle number,route number,vehicle type and vehicle head coordinate are obtained by VISSIM simulation,and the failure probability of traffic sign is calculated according to the three conditions of occlusion and the calculation formula of failure probability of traffic sign.Aiming at the problem of vehicle occlusion traffic sign,this paper introduces the concept of redundancy,and puts forward four methods for the redundancy setting of traffic sign:repeated settings for multiple locations,prompt information decomposition for complex traffic signs,complementary traffic sign setting for the same location,and combination setting of signs and markings.Combining the process of driver's recognition of traffic signs and the analysis results of traffic signs occlusion,two assistant measures are put forward:optimizing the layout of traffic signs and controlling the number of large vehicles in lanes.Through theoretical analysis and experimental verification,the effectiveness of several setting methods is analyzed,and the results show that the proposed method is feasible to reduce the failure probability of traffic signs.