Development of a Model for a Cordon Pricing Scheme Considering Environmental Equity: A Case Study of Tehran

Congestion pricing strategy has been recognized as an effective countermeasure in the practical field of urban traffic congestion mitigation. Despite the positive effects of congestion pricing, its implementation has faced problems. This paper investigates the issue of environmental equity in cordon pricing and a park-and-ride scheme. Although pollution decreases inside the cordon by implementation of cordon pricing, air pollutants emission may increase in some links and in the whole network. Therefore, an increase in air emissions in the network means more emission outside the cordon. In fact, due to the implementation of this policy, air pollutants emission may transfer from inside to outside the cordon, creating a type of environmental inequity. To reduce this inequity, a bi-level optimization model with an equity constraint is developed. The proposed solution algorithm based on the second version of the strength Pareto evolutionary algorithm (SPEA2) is applied to the city network in Tehran. The results revealed that it seems reasonable to consider environmental equity as an objective function in cordon pricing. In addition, we can create a sustainable situation for the transportation system by improving environmental inequity with a relatively low reduction in social welfare. Moreover, there are environmental inequity impacts in real networks, which should be considered in the cordon pricing scheme.