Mode Split Model And Its Application On Urban Passenger Transportation System

Passenger traffic structure, which is an important index for reflecting the mode of passenger traffic system, stands for the mode split of different travel mode in a passenger traffic system. The adjustment of passenger traffic structure fully embodies the emphasis of urban transportation policies. It reflects the reasonability and efficiency of utilization of resources in specific region.The urban development patterns and policies of typical urban cities in China were analyzed in this paper. Generalized Cost Model based on service characteristics (SCGC model) was built by studying the influences of supply-demand balance and travel characteristics of urban transportation. On the basis of the SCGC model, modal split model based on service characteristics (SCGC-STM model) was built. The SCGC-STM model was calibrated and tested by using Beijing Resident Trip Survey data over the years. The elasticity of mode share rate with respect to the factors was modeled and analyzed by SCGC-STM model. A mathematical elasticity model based on factor characteristics was built, and it was used for quantitative analyzing of the elasticity of factors. Finally, comparison of the comprehensive transportation system under different policies was analyzed and the ideal aim of the development of the traffic structure policy system was discussed. The main research contents and results of this paper are:(1) On the basis of referential review of domestic and foreign bibliography, research methods of comprehensive traffic structure, mode split model and modal share mechanism were summarized and analyzed, and shortcomings of existing research were present. The developing patterns and evolution mechanism of traffic structure in domestic and foreign urban indicate that Travel Demand Management is an effective measure for building perfect service system and sustainable-developing traffic structure. From the standpoint of policy makers, during the pre-stage of urban planning, it is a good way to appreciate the importance of expecting target by making effective travel demand management policies and grasping the change of traffic structure under certain policies.(2) Distribution fit of travel distance, travel speed and travel time of each travel mode was made by studying the probability density function. The study showed that k-order Erlang distribution function presented good fitness. In the respect of travel time, the randomness of bicycle travel time was the lowest. The randomness of car and taxi travel time was higher, and the randomness of bus travel time was highest.(3) Mode Split Model based on service characteristics (SCGC-STM model) was built. The service characteristics of each travel mode were quantized as time or fare, and the generalized costs were then calculated. Four indexes of service characteristics were chosen:Economic Cost, Time Cost, Service Accessibility, and Comfort Factor. After the generalized costs were calculated, the SCGC-STM model was calibrated and its fitness was tested by using existing data. The result showed that the relatively error of SCGC-STM model for forecasting modal share rate was less than 10%, presenting good fitness.(4) A mathematical elasticity model based on factor characteristics was built. The factors, which influence mode share rate, were divided into two categories:factors with randomness characteristic and factors without. The elasticity of each factor was separately analyzed as random elasticity and direct elasticity. The basic and variation characteristics of each elasticity type were then analyzed trough actual cases. The analytic results of random elasticity showed that:along with the decrease in the randomness of the factor, the randomness of mode share rate elasticity with respect to the factor decreased correspondingly.(5) The city center in Beijing was chosen as research object. The person km, average travel time etc. of the region during AM peak under bus speed policy, bus capacity policy, road charge policy and comprehensive policy were quantitatively analyzed. The main results included:increasing bus travel speed would greatly reduce the average travel time, and increasing bus capacity would greatly promote bus person km, but both policies had little impact on the average travel speed of the region. Road charge policy reduced the trip ends in city center, urged car group to turn towards other travel mode such as public transport etc, relieved the traffic load and traffic congestion of the city center. Each single policy has its limitation, comprehensive policy which synthesizes each single policy can have a better outcome and realize ideal strategic target for optimizing traffic structure.