Research On Merging Area’s Capacity Of Chang’aninterchange Based On VISSIMSimulation

As the node of the urban expressway networks,the traffic capacity of urban ring roadsalternative interchange is the key to improve the traffic capacity of the whole roadnetwork.Nowadays, urban express road system were built in many city of china, especiallyurban freeway system is achieved considerable development in these years.However,thecorresponding theoretical research is relatively backward, especially in terms of research onthe part of the various components and the overall the traffic capacity freeway interchangesystem even less,This is adverse to the planning and design and type selection evaluation ofexpress road alternative interchange system.And the merge area of alternative interchange is avery important part of it, because of merge of cars in acceleration lane leads the disorder ofmainline traffic, further more low the speed of cars. In the end this area become a bottleneckof express road system. Therefore, it is very necessary to make a future study.This article in connection with the merge area of the second ring of south Xi’an andcarry out the study on the capacity of interchange merge area.and through different statisticalintervals comparative analysis, then get the statistical interval time which is suit with thetraffic characteristics in the merge area of the interchange in Chang’an. Then based on thestudy to have a further analysis, further more get the relationship between the speed andcapacity of the same place in different roads. Based on those actual observation data and theanalysis of the relationship between speed and traffic flow, get the result that the traffic flowis about5500pcu every hour and the critical velocity is about34.79kilometer every hour.The study on the capacity of merge area in the southeast of the second ring of Xi’an, thenuse the simulation software of VISSIM to simulation it, and rely on the traffic flow to test andverify the effect of simulation model. Through increase the input capacity value, ultimately,get the biggest merge area capacity is when the capacity in mainline get4300pcu/h, and1350pcu/h in import ramp. Finally the real capacity value in merge area of Chang’aninterchange bridge is5650pcu/h.