| As an important means to connect urban center and metros,regional rapid rail transit should play a leading role in transforming city structure,promoting development along the line and facilitating residents’ commuting and travelling.with the metro system in urban has been built and perfected in Beijing,Shanghai,Guangzhou and other big cities,regional rapid rail transit’s construction will become the main battlefield of urban rail transit.Different from metro lines,regional rapid rail transit has its unique service range,functional positioning and line features,so the full play of its function is closely related to its planning technical indexes.Based on the technical analysis of regional rapid rail transit’s characteristics and aimming at two aspects of passenger travelling time and operation net benefits,the coupling optimization model of three technical indexes for regional rapid rail transit’s line planning—rail line length,average station spacing and maximum design speed,has been built,and a quantitative analysis method for the selection of the main technical indexes is constructed.The main contents and achievements of this paper are described as followed:(1)On the basis of the further research on regional rapid rail transit development and research status at home and abroad,this paper defines the definition and connotation of regional rapid rail transit.Deviding regional rapid rail transit into three kinds from the perspective of connecting with urban rail transit network,and combining the network structure of three typical cities-Paris,Tokyo,New York to illustrate.Combining regional rapid rail transit practice at home and abroad,the characteristics are analyzed including functional orientation,the characteristics of passenger flow,technical standard and the operation organization.(2)The influence factors and reasonable range of the three main technical indexes-rail line length,average station spacing and maximum design speed are analyzed.Based on the theoretical research and the analysis of four typical methods for single index calculation,this paper points out the strong coupling between the three indexes.and proposes the necessity of establishing a coulping optimization model for rail line length,average station spacing and maximum design speed.(3)By constructing the function of passenger flow demand density,taking the shortest travelling time and maximizing the net benifit of operator as the targets,and taking rail line length,average station spacing and maximum design speed as the decision variables,this paper establishes a multi-index nonlinear coupling optimization model.The optimization model realizes the coupling analysis of the three indexes,while overcoming the defects in existing research mole,such as only considering the pedestrian,ignoring the distribution of passenger flow,too many experience values of parameters,and the optimization objective is too simple,etc.Then,this paper converts double objectives to single objective by introducing social net benifit and time value.Finally,the method of solving the optimization model is given by using the genetic algorithm,and the solution is realized by programming.(4)Taking the Beijing Fangshan line as the example,the coupling optimization model is used to caculate and analyze.The calculation result shows that the optimal solution of the main technical indexes of Fangshan line is that:rail line length,22.8km;average staion spacing,3.8km;maximum design speed,120km/h.When comparing with the planing scheme of Fangshan line,the rail line length is reasonable,but the average staion spacing and maximum design speed is too conservative.If the coupling optimal solution is adopted,it will increase 38.01 million yuan of operational social net benifit per year.The sensitivity analysis of passenger traffic and time value is also been carried out for the model,and the result shows that the sensitivity of rail line length is relatively high and the sensitivity of average station spacing is general.The coupling optimization of main technical indexes for regional rapid rail transit line planning can be used to calculate the coupling solution of rail line length,average station spacing and maximum design speed under the dual tagets of passenger travelling time and operation benifit,which can provide a reference for the planning of the regional rapid rail transit. |
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