Research On The Optimization Of Multilane Expressways Traffic Sign Based On The Occlusion By Heavy Vehicles

With the sustained and rapid economic development,the road traffic grows rapidly,a lot of four-lane highway which is built completion in the early year has gradual emerged serious traffic congestion and expansion of them has become eight-lane highway.Because of the existence of various vehicles in traffic,vehicles in eight-lane highway are running significantly faster,the number of them is increased greatly while the driver of a light vehicle will not be able to read a sign due to occlusion by leading heavy vehicle,there are two cases: one is the light vehicle drive on the fast lane of the highway,their sight to the traffic signs set on the right side of the highway are usually obscured by heavy vehicles driving on the slow lane,another is the driver of a light vehicle will not be able to read a sign because of a leading heavy vehicle.Clear signs can provide road information,guide the direction of action and make the correct driving action in a timely manner,so it’s important to estimates the probability of a sign being occluded by heavy vehicle set a reasonable traffic sign.This paper analysis the high-speed exit safety,lead two kinds of occlusion phenomenon through the different lane function program,and analyze the relevant factors related to occlusion,mainly including the following four factors: vehicle type,traffic condition,driver visibility and sign parameters.Next,the key research is model of roadside traffic sign,in this paper,for the first time solve the problem of occlusion by heavy vehicles with VISSIM software,and there will have different models respectively the roadside traffic sign and overhead sign.In the process of modeling,determine critical conditions that sight of light vehicle obscured by heavy vehicle within the legibility zone firstly,and the critical condition can by some dynamic basic data,including link coordinate,following distance and so on,and these data is obtained with VISSIM simulation.Then simulation of vehicle operation under different road traffic conditions,statistical analysis of simulation results shows the target data such as occlusion time and occlusion probability.Finally,focuse on the problem of occlusion,combined with the defect of traffic signs on multilane expressways,and according to the calculation of the probability of occlusion,Put forward a number of measures to improve traffic signs,such as mark the deflection angle,simplified layout design,in addition,can take the appropriate measures to compensate for the role,such as traffic signs repeat settings,combination signs and markings and so on,so that the driver can identify the expressway traffic signs information more fully and accurately.