Research On Signal Control Optimization At The Urban Intersection Based On The Meteorological Conditions

This paper aims at the typical poor weather condition in Chengdu-fog(haze)and explores signal control optimization at the urban intersection based on meteorological conditions under poor weather conditions,to mitigate the adverse effects and improve traffic safety and traffic efficiency.First of all,taking the traffic flow parameters of through lane collected in the field as the research object.Using Shapiro-Wilk test and independent sample t-test to extract the saturation headway and then saturation flow rate and total start-up loss time are calculated.Through statistical analysis,correlation analysis and regression fitting,the impacts of the poor visibility conditions caused by fog(haze)on the saturation headway,saturation flow rate and total start-up loss time were quantitatively studied.The three-exponential regression model of saturation headway,saturation flow rate and visibility are given.It is verified that the model accuracy is high and can reflect the rule of influence in real state.And compare the model with the research results of related literature at home and abroad.Then,proposed parameter correction process of the microscopic traffic simulation model VISSIM.Single-factor sensitivity analysis and X-Y scattergram method were used to select the final calibration parameters and the range of values.The calibration parameters were calibrated by orthogonal test,and the values of the expected speed,the average parking distance,the additional part of the safety distance and the multiple part of the safety distance under the ideal and poor weather conditions were clarified.Taking the percentage of average absolute error as the simulation accuracy index of saturation flow rate.It is verified that the corrected model is credible and reliable and can reflect the actual traffic conditions in China.Based on the parameters correction of the microscopic traffic simulation model,the influence of signal timing with the ideal visibility conditions on traffic flow under the poor visibility conditions is studied.It is found that the signal control of the ideal visibility conditions is not applicable under the poor visibility conditions.It may be considered to optimize signal control under the poor visibility conditions.Finally,taking the intersection of Xinhua Avenue and Renmin Middle Road in Chengdu as an example,the research on signal control optimization based on meteorological conditions is carried out.Select the vehicle average delay output by VISSIM as the optimal target.The genetic algorithm is used to optimize cycle time and green time.The VISSIMbased genetic algorithm achieves automatic calculation from microscopic traffic simulation to signal control optimization under poor visibility conditions.The optimized signal control is compared with unoptimized signal control under poor visibility conditions.It is found that the optimized signal control is more adaptable to the operating characteristics of traffic flow under poor visibility conditions and can reduce the vehicle average delay of the intersection by 7.1%.