A multi-class toll-based approach to reduce total emissions on roads for sustainable urban transportation

High toll charges force trucks to avoid quality roads, leading to increased emissions. We propose a model in this study to find an effective toll charging scheme to minimize total network vehicular emissions while maintaining reasonable revenue for investors. A bi-level modeling approach is used, where toll prices for multi-class vehicles are decided in the upper level and user response to toll charges are predicted using user equilibrium conditions with multi-class traffic assignment in the lower level. The model takes into consideration both toll revenue and total vehicle operating costs to produce an acceptable solution for both investors and road users. All major components of hazardous emissions were considered and estimated using secondary data, quantifying their impact on human health and the environment. The application of the model was illustrated using two networks considering different toll charging scenarios and near-optimal solutions were found for each toll-charging scenario. The results revealed that commonly used toll schemes are inefficient with respect to multi-stakeholder objectives. The optimized toll charging scheme was able to reduce the total emission costs of the network by 12 % compared to the toll scheme currently used by a toll facility in a real network in Melbourne, Australia.