Study On Signal Control Method Of Adjacent Region Between City Expressway System And Conventional Road Network

Along with the increasing of traffic demand, urban traffic congestion is getting worse and worse.City expressway system with the features of speediness and large capacity has taken a high proportion of traffic travel, however the congestion of adjacent region has greatly weakened the function of city expressway system.Therefore, based on existing road infrastructure conditions,it has an important practical significance to research the coordinated signal control of on-ramp, off-ramp and upstream and downstream sideway intersection in adjacent region for alleviating traffic congestion.Based on analysis of the function,characteristics,adjacent form and control method of the adjacent region,Xizhimen North Main Street from WenHui Bridge interchange to MingGuang Bridge interchange is selected as the research object and the traffic data are collected.First of all, fuzzy comprehensive evaluation method is used to evaluate the three operation states of smoothness,crowdedness and congestion for adjacent region through building evaluation index system of adjacent region.And the time interval of crowdedness state is confirmed and selected as research period in this study.Secondly, four single-point control schemes are determined by calculating metering rate of on-ramp and off-ramp sideway based on volume and time occupancy ratio model, and by adjusting the signal control scheme of upstream and downstream sideway intersection based on Webster model.Thirdly, the model of coordinated signal control for adjacent region is put forward based on single-point control schemes.More specifically, the coordinated control between on-ramp and off-ramp is determined by considering the length of expressway additional lane as control condition,and the signal control schemes of upstream and downstream sideway intersection are optimized by on-ramp and off-ramp sideway metering rate.During the exploration, all intersection signal adjustment schemes are listed, analyzed and compared one by one.In order to satisfy the traffic requirements of the two sides of expressway,a intersection control fusion method is proposed to integrate the intersection schemes.Besides, the optimized signal control scheme of adjacent region is determined by the intersection control fusion and sideway coordinated control method.Finally, after parameters calibration of the simulation model by traffic data and each point signal control scheme,the effectivity of the model is proved by t-test using traffic volume and average speed of expressway main road and sideway as variables.And the signal control of the adjacent region is simulated by VIS SIM to prove the reasonableness of the area coordinated control model.The result shows that after taken coordinated control, the traffic volume and average speed of expressway main road have averagely increased by 22.1% and 24.5% while that of sideway reduced by 30.9% and 22.0%.Hovever, the traffic running state of the whole adjacent region has averagely increased by 4.97% which proves the effectiveness and feasibility of the area coordination control model.