Study On The Model Of The Traffic Evacuation In The Mountainous Cities Based On Large-scale Activities

With the growing of our economic strength and international influence,it is more frequently for the central and western mountainous cities to hold large-scale activities,which brings lots of traffic pressure to the limited resources of the mountainous cities.In order to ensure the large-scale activities are held successfully in the mountainous cities,we should take full account of the unique road network characteristics of the mountainous cities,and combine the traffic characteristics of large-scale activities and the road network of mountainous cities to solve the traffic evacuation during the large-scale activities.Based on the analysis of the research actuality at home and abroad,this paper considered comprehensively both two factors of road network characteristics of the mountainous cities and the traffic characteristics of large-scale activities,quantified the scope of traffic impact of the large-scale activities that held in the mountainous cities,and researched on the model of the traffic evacuation in the mountainous cities during the large-scale activities.Firstly,the characteristics of road network in mountainous cities and the traffic characteristics during the large-scale activities are analyzed in this paper.The unique natural barrier in mountainous area restrict the freedom extending of mountainous road network,which makes the road longitudinal slope of the mountainous city is relatively large,the non-linear coefficient is large and the road network reliability is poor.The characteristics of road network in mountainous cities were analyzed from three respects including the characteristics of network layout,transit travel characteristics and traffic flow characteristics in this paper.The traffic trip is different from regular trip during the large-scale activities,the traffic characteristics during the large-scale activities were analyzed from two respects of the characteristics of traffic demand and traffic flow in this paper.Secondly,in this paper the traffic characteristics during the large-scale activities and the characteristics of road network in mountainous cities were combined,the qualitative and quantitative methods were used to quantify the scope of traffic impact of large-scale activities that held in the mountainous cities.According to the experience identified the preliminarily scope of traffic impact of the large-scale activities,using the road service level(V/C)as the threshold of traffic impact to analyze the boundary road of the preliminarily scope of traffic impact quantitatively,and compared the changes of the road service level of boundary road before and after the activities.Thirdly,the traffic distribution law during the large-scale activities was analyzed from two aspects of pedestrian and vehicle,combining with the features of road network in mountainous and introducing the idea of bi-level programming to establish the bi-level programming model of the traffic evacuation during the large-scale activities in the mountainous cities.Then,using the genetic algorithm toolbox of MATLAB to solve the model,and put forward the traffic evacuation optimization control measures during the period of large-scale activities.Finally,the Chongqing Olympic Sports Center was taken as an example.The methods of identifying the scope of traffic impact of large-scale activities that proposed in the paper was used to identify the scope of traffic impact of large-scale activities that held in the Olympic Sports Center,and the bi-level programming model of the traffic evacuation distribution which was established in this paper to distribute the traffic during the period of large-scale activities.Then the results were compared with conventional TransCAD traffic assignment to verify the feasibility of the bi-level programming model for the allocation and put forward the corresponding measures of traffic evacuation for the Olympic Sports Center.