Study On Optimization Of Urban Road Network Characteristics Considering Fuel Consumption

With the acceleration of urbanization in China,urban traffic problems ars becoming more and more serious,especially traffic congestion and energy waste,and the unreasonable structure of urban road network is one of the main causes of traffic problems.However,the reasonable urban road network structure,can not only meet travel demand,improve network efficiency,but also reduce the total fuel consumption of the network.Therefore,it is necessary to consider the influence of urban road network structure on the whole urban traffic system,in the urban planning and design.From the viewpoint of energy consumption,the rationality of the macroscopic structure of road network is analyzed in this paper.First of all,from the macro point of view,the local network analysis of the microstructure of intersection is carried out.The fuel consumption of the intersection can be calculated,by defining the capacity and impedance functions of the intersections,and using the steering flow matrix and impedance matrix to record the flow distribution results.Besides,the calculation model of fuel consumption can be obtained,on the basis of determining the relationship between fuel consumption and fuel consumption index function.Secondly,Taking the road network structure characteristics as the research object,and the total travel time and the total fuel consumption of the road network as the optimization objective,a bi level programming model is established to evaluate the rationality of road network structure,combined with the fuel consumption calculation model of road network,which was established before.In the lower level problem,the improved SUE model is used to allocate the network traffic,and the route choice behavior is constrained by the total fuel consumption;and the total fuel consumption of the road network is constrained by the minimuml travel time in the upper level problem.Finally,road network spacing and road network gradation are optimized combined with the bi level programming model of road network structure.According to the assumed road network conditions and the recommended spacing values of all kinds of planar intersections,the optimal spacing of main road network and secondary road network are given by the numerical examples.What’s more,the optimization strategy of road network gradation under different road network spacing is analyzed.Thus,the validity of the model and its algorithm are verified.