چكيده به لاتين
Abstract
Traffic congestion is one of the main economic costs that is created by choosing the wrong path by users in the network. One of the tools to reduce traffic congestion is cordon pricing scheme that is as an effective approach for travel demand management. But always cordon charging issue, due to its inequitable effects especially on drivers, hasn't been acceptable by drivers and policy makers. Our study shows that two inequalities are created by the implementation of cordon pricing, including the spatial and the environmental inequity. In first type of spatial inequality, some drivers for travelling to a destination with in the cordon or should pass through it will face with increasing in travel time. In second type of inequity, drivers whose origin is located within the cordon will face with inequality. Because the home location of these drivers is located within the cordon, they have to pay toll and they cannot change their path and choose longer toll free pass. Therefore, these drivers face with inequities. Furthermore, although air pollution emission is reduced by the implementation of the cordon pricing, but air pollution emission may increase in some links and the whole network. Increase in emissions in the network, due to its reduction within the cordon, means a further increase in emission in the out of the cordon. In fact, by the implementation of the cordon pricing policy, air pollution emission may be transfer from within the cordon to its outside. Therefore, this problem creates environmental inequity to people (users and non-users of transportation systems). Finally, considering mentioned inequities, a bi-level multi-objective optimization model with constraint has been developed. The proposed model has been applied on Sioux Falls network as a numerical example. The results of the developed model show that:
• The final proposed model is able to consider the objective functions including the social welfare, the spatial equity, and the environmental equity at high level problem and act as a multi-objective model.
•The final proposed model is able to consider a multi-class multi-modal traffic assignment as at low-level problem.
•The final proposed model is able to consider the effect of Park & Ride around the cordon to show drivers’ behavior for mode shifting from private cars to taxis and buses.
•The final proposed model, by using a method based on Pareto front, instead to provide an answer, is able to generate a set of suitable answers. Therefore, decision makers can choose a suitable answer based on the importance of problems such as social welfare, spatial equity, and environmental equity.
•The final proposed model, by using a heuristic method, is able to solve the logical constraint problem of meta-heuristic methods to generate random answers for cordon location.
•The spatial and environmental inequity problems create in the real world by the implementation of cordon pricing policy and the proposed model is an appropriate tool to solve these problems.
•The final proposed model can reduce the inequity problems and increase public and policy makers acceptance to implement this policy.
•The results of proposed model indicate that, by the formation of Pareto front, the equity functions are in contrast to the social welfare function and therefore the multi-objective approach is reasonable.
•The results of proposed model indicate that, by researching in solution space and choosing another answer, we can reduce inequity problems with low reduction in social welfare in many cases.
Keywords: Cordon Pricing, Spatial Inequity, Environmental Inequity, Bi-level Multi-objective Optimization Model, SPEA2.