Study On Traffic Operation Characteristics Of Small Interval Interchange In Urban Roads

Interchange is an indispensable part of urban road traffic,which plays a crucial role in sorting out urban traffic flow and improving the conversion efficiency of traffic flow.With the denser of the road network,on the one hand,interchanges on urban roads have become denser,on the other hand,interchanges have become more difficult to maintain.In some cities,limited by terrain conditions or existing road network conditions,interchanges with small spacing become an inevitable choice.Although there are auxiliary lanes between these interchanges,the interleaving area is still the bottleneck of traffic operation.Therefore,it is necessary to study the traffic operation characteristics of the interleaving area of the urban interchange with small distance in operation.This paper takes the intersection area between no.9 overpass and Xinhua overpass in Dadukou district,Chongqing city as an example.On the basis of traffic investigation,the traffic capacity of the intersection area is studied by means of simulation analysis method:Firstly,the analysis of the survey results shows that when the length of the interleaving area is small,the interleaving vehicles will change lanes in the upstream of the interleaving area and enter the lane nearest to the target lane in advance.The lane change in the interleaving area is mainly the lane change of the interleaving vehicles,which reaches more than 90%.In the middle of the interleaving area,about 80% of the interleaving vehicles have completed the lane change.In the middle section of the interweaving zone,the location of the outer lane and the first auxiliary lane presents a skewed distribution of vehicle speed,and the potential accident probability is greater in these two lanes.In the interleaving area,the vehicles in the non-interleaving lanes follow the shift negative exponential distribution,while the vehicles in the two interleaving lanes follow the improved M3 distribution.The quadratic relation of velocity and flux and the quadratic relation of flux and density are obvious,but the linear relation of velocity and density is not obvious.Secondly,the traffic capacity of the interleaving area of the simulation model is used to analyze.The analysis shows that for the class B overpasses of urban roads,part of the turning traffic has a plane intersection,and there may be more transverse interference at the entrance ramp or the connection part between the ramp and the main line,thus affecting the traffic operation in the interleaving area.At the same time,the capacity of interleaving zone under different flow ratio and truck ratio is obtained by simulation solution,which can be used as a reference for engineering design.Finally,three measures are put forward to increase the length of interleaving area,add auxiliary lanes and strengthen traffic management.The model verifies the feasibility and effect of adding auxiliary lane.