Study On Traffic Demand Management Strategy And Scheme Optimization During Bridge Maintenance In Mountainous City

Mountain cities are affected by mountains and rivers,and the Bridges and tunnels are widely distributed and numerous.As the traffic link between various groups in the city,Bridges are the core part of the road traffic network,and also the weakest part of the road network.With the increasing total number of motorized trips and the increasing demand for river crossings,Bridges are often overloaded with problems such as aging bridge decks and falling facilities.Therefore,bridge overhauling has become a thorny problem faced by mountain cities.Most of the roads along the bridge are concentrated distribution zones of congested sections and nodes,and the form of overpass between the entry and exit nodes is complex and diverse.Therefore,its maintenance is bound to have a serious impact on the roads along the bridge and even the urban road network.It is difficult for traditional traffic organizations to meet the requirements of bridge construction organizations.By reducing the traffic demand,the contradiction between supply and demand can be alleviated to ensure the traffic operation during the construction period.Traffic demand management provides a new idea for the balanced distribution of bridge maintenance and construction.In this paper,research methods including induction method,qualitative analysis and quantitative calculation method,questionnaire survey method,and analytic hierarchy process(AHP)are used.On the basis of systematically reviewing domestic and international construction transportation organization and demand management measures,this paper focuses on the following research.Firstly,from the urban spatial layout,traffic infrastructure,traffic operation and other aspects of the mountain city dynamic and static characteristics,and from the construction difficulty,traffic impact and other aspects of the mountain city bridge maintenance traffic organization of the key points and difficulties.Secondly,the advantages and disadvantages of current construction traffic organization strategies are systematically sorted out,the adaptability analysis of traffic demand management for major bridge repair in mountain cities is carried out,and the implementation conditions of traffic demand management strategies are put forward.Thirdly,combined with the road network structure,traffic operation and the travel characteristics of citizens within the construction bridge itself and its influence area,the detailed program formulation process covering the restricted driving area,the restricted driving period and the restricted driving model was proposed,and the plan was preliminarily formulated.Fourthly,travel purposes were divided into home-based travel for work(HBW),home-based travel for school(HBS),home-based shopping(HBSH),home-based other travel(HBO),and non-home-based travel(NHB),and the model was optimized.The "four-stage method" was used to output the main evaluation parameters,and a road network evaluation model was constructed,which included eight impact factors such as operating speed,flow equilibrium value,difficulty in implementing the number limit and mass influence.AHP method was used to determine the judgment matrix and the weight of each indicator,conduct a comprehensive quantitative analysis of each restriction scheme,recommend the implementation scheme according to the evaluation results,and put forward Suggestions for node optimization.Through the example of Chongqing Jialing Bridge’s tail-limiting traffic,it proves the correctness of the Traffic demand management strategy of using the motor vehicle tail-limiting traffic during mountain bridge repairs.According to the evaluation results of the model,Chongqing traffic management department finally implemented the plan of "limiting 3 Bridges".According to the data of the road monitoring system in the main urban area of Chongqing,the relative error of the model in predicting the operating speed is 5.2%,and the relative error of the congestion mileage is 5.7%,both within 6%.The model has high accuracy."One ban and three restrictions" in the main urban area is the first attempt of traffic demand management in Chongqing,a typical mountainous city.The implementation effect was unanimously recognized by the government departments and the public.It provides an important reference for the development of Traffic demand management strategies and plans during bridge or important arterial roads maintenance in other mountain cities.