Simulation-based Optimization of HOT Lane Tolls

This paper presents a real-time simulation-based control framework to determine dynamic toll rates in order to optimize an operator's objective, subject to various operational and contractual constraints, such as smooth toll rate changes and maintaining prescribed levels of service on the toll lane. The toll-setting system incorporates models to predict the vehicle arrival process upstream of the toll lane facility and drivers' choice whether or not to use the toll lanes as a function of the toll rate and travel times presented to drivers within the information system. A macroscopic traffic simulation model is used to predict the flow conditions within the prediction horizon. The travel times provided to users as information and the ones predicted by the traffic flow model are iterated until consistency between them is obtained. The whole process is embedded within an optimization algorithm that sets tolls that optimize a given objective function. Several case studies demonstrate the use of this framework and its potential to provide useful toll settings.