Study On The Capacity Of Comprehensive Waiting-area For Through Vehicles At An Isolated Intersection

The comprehensive waiting-area for through vehicles is a kind of intersection refinement method based on the improvement of the comprehensive waiting-area.By adding a parking line and a set of pre-signal lights to the entrance of the original intersection,the through vehicles can take full advantage of the waiting area formed between the parking lines,increase the capacity of the entrance of the intersection and effectively avoid many drawbacks of the traditional intersection reconstruction method.At present,the situation of the research on the comprehensive waiting-area for through vehicles is few,most of the research is mainly concentrated on the traffic organization of the comprehensive waiting-area,while the research on the capacity of it is very rare.So the paper analyses the research results of the comprehensive waiting area,focusing on the effect of setting up the comprehensive waitingarea for through vehicles on improving the capacity of the intersection entrance road.Firstly,the traffic flow characteristics of signalized intersections are introduced,and the similarities and differences of traffic flow characteristics after setting up waiting areas are analyzed.The geometric conditions,flow conditions and signal control conditions of setting up waiting areas are summarized.At the same time,after the waiting area is set,the vehicle will not be queuing twice as the basis for setting the length of the waiting area,and the critical setting length of the waiting area is obtained.The coordinated control of main and pre-signal and the green light interval time after the waiting area is set are studied,the optimization model of minimum effective green time of the import main signal is established and the influence of the setting of the waiting area on the green light interval is revealed.Then,VAGAS software is used to process the video of the survey intersection,and SPSS software is used to analyze the distribution law of headway,the saturation headway time,the saturation flow rate and the start-up loss time of the vehicles in different lanes before and after the waiting area,which provides data support for the traffic capacity enhancement model.The analysis of the survey results shows that there is no significant change in the distribution law of headway,the saturation headway time,the saturation flow rate and the start-up loss time of the straight-through vehicles.However,for the left-turning vehicle,the vehicle reached the saturation flow rate changed from the 4th to the 2nd.At the same time,the start-up loss time is reduced by about 3.43 s.Next,a model for improving the capacity of the comprehensive waiting-area for through vehicles was constructed which based on survey results.Finally,the intersection of Houhai Avenue and Haide Yi Road is analyzed as an example,and based on the previous analysis,the signal timing of the existing waiting area is optimized.Then,the comparative analysis is carried out to verify the improvement of capacity of setting waiting-area under different timing conditions.And at the same time,the change of the capacity of different waiting area lengths under the same signal timing conditions are studied.The results show that the straight-through capacity of the imported road is greatly increased by 133.8% after the waiting area is set,and the traffic capacity is improved with the increase of the length of the waiting area.For the left-turn capacity,the loss time is reduced after the waiting area is set.The ability increases slightly by 13.6% and is less affected by changes in the length of the waiting area.At last,to verify the applicability and accuracy of the model,the paper verifies the improvement of the capacity change from the perspective of simulation and model.The results show that the model can better describe the reality and prove the applicability and accuracy of the model.