Optimization Of Transit Network Based On Equity

Social equity is fundamental requirement for building a harmonious society and key to maintain social stability and economic development. Equity from people oriented in the field of public transit remand to achieve the rational allocation and optimization of public transit resources, take into account of all the rights of equitable access to public transit resources and the difference among the different people and in different regions. Optimization of public transit network is an important means of allocation of public transit resources. The current optimization of public transit network, people usually optimum a system as the target without equity. Some happened such as transit system has been optimized, some areas or some people did not benefit even damaged. This will be a new problem for the scholars to guarantee the equity of passengers' travel interests in transit network optimization, prevent to appear two polarized phenomenon of "more excellent, poor worse" after optimization.This paper introduced equity to public transit fields just for this purpose. The connotation of public transit equity is to provide passengers'equal chance to participate in social activities, which essence is that passengers equally use the public transit resource and the convenience produced by the resource. The equity of public transit has two forms: Horizontal transit equity is the comparison of resource or interest between oneself and others, such as the comparison of transit resources among many people on the same network; vertical transit equity is the comparison of resource or interest owned by oneself in different time, such as the comparison of travel interests Before and after the optimization for the same individual or group. The paper focused the research on the last one according to the object of transit network optimization: It should avoid to sacrifice some OD's travel interest and make them worse than before in transit network optimization; If cannot avoid, it should control the extent of inequity within the some limits.The paper established the indicator of transit equity such as travel time equity, travel cost equity,travel accessibility equity and transit route equity. It could measure the degree of benefit or damage which passenger suffers after optimization It established the model of transit network optimization which contains equality constraints and other regular constraint, solved the model by Ant colony algorithm. The model aims to the maximum direct traveler density, first sets the sections of largest passenger density as candidate lines at in the algorithm; the equality constraints control the damaged interests of OD to a certain extent, them reflects the consciousness of "key priority, relatively equally optimization" for crowded section.Finally, an example was put forward to verify the optimization method in this paper. The results show that the equality constraints controlled the damaged interests of OD to a certain extent, when the overall benefit of transit network achieved, it also proved the feasibility of the method this paper.