Research On The Optimization Of County-level Bus Network Under The Guidance Of Low Carbon

With the development of county economy,residents travel demand continues to grow,however,the development of public transport is relatively backward compared to car,leading to a large optimization space for public transport system.In response to the goal of "Reaching the Peak of Carbon" in China Government Work Report and green development for new urbanization,the low-carbon travel has become a key research direction of transit system in counties and towns and public transportation shoulders the responsibility of reducing carbon emissions.This paper relies on Research on Network Configuration of Typical Facilities in County Towns Based on Total Carbon Efficiency(No.2018YFC0704704)under the national key R & D project Research on County-level Urban Planning Technology Based on Carbon Control System to carry out the optimization of county-level public transport network under the guidance of low-carbon,aiming to provide theoretical reference for improving transport efficiency and reducing carbon emissions of public transport in actual operation.(1)This paper fully analyses and summarizes the travel characteristics and public transportation status in the county based on the questionnaire survey and statistical analysis.Travel characteristics include travel structure,travel time distribution and travel distance distribution.This paper discovers county town bus network layout,bus network technical indicators such as line length,station distance and repetition coefficient,vehicle size,urban and rural bus passenger flow distribution and fuel consumption intensity.(2)This paper combs the calculation ideas,methods and formulas of carbon emission,corrects the carbon emission coefficient,estimates the carbon emission intensity of pure electric vehicles,LNG vehicles and diesel vehicles according to the operation situation,and calculates the carbon emission control indicators of each example county.Through comparative analysis,it is found that the total carbon emission of public transport in county is far less than that in big cities,but the carbon emission of single trip is greater than that of big cities.The total carbon emission between county towns depends on the scale of public transport network,and the carbon emission characteristics differ from routes significantly.(3)This paper discusses and summarizes the general development modes of county-level public transport from the perspectives of town type,transport structure,bus network forms and bus line types.It is verified that passenger volume is the key factor affecting the carbon emission of county towns through stepwise regression and the low-carbon scenario design.The lowcarbon development mode of public transportation suitable for the four counties is judged.The development path of low-carbon public transportation is analyzed based on planning process,and the optimization of bus trunk network is defined as the key point of carbon control in public transportation system.(4)This paper constructs the optimization model of County-level bus trunk network with the goal of minimizing the carbon emission of a single trip.Based on the node importance and service efficiency,the selection of initial and terminal stations and alternative routes is carried out,and the genetic algorithm is applied to solve the model to obtain the optimal layout scheme under the current parameters.In order to meet the demand of bus travel,the passenger flow conditions are tested,and the layout scheme that meets the conditions is put into the evaluation pool.The evaluation index system of public transport system is established with low-carbon as the guidance,and the comprehensive evaluation method is constructed with grey correlation method.The optimal scheme in the evaluation pool is compared and selected,and the optimization effect of the final layout scheme of public transport trunk is evaluated.