Robust Tolling Schemes for High-Occupancy/Toll (HOT) Facilities Under Variable Demand

摘要

High-Occupancy/Toll (HOT) lanes have become an increasingly prevalent form ofcongestion management pricing in the U.S. over the past few decades. The success of a HOTfacility is dependent on the pricing scheme implemented, which determines the utilization ofthe HOT lane, and the corresponding congestion relief on the parallel general-purpose (GP)lanes. An additional complexity in determining HOT tolls arises from the inevitablevariability in travel demand, which is inherent to transport networks. A successful tollingscheme, whether fixed or time-varying, must therefore be robust to changes in travel demand.In this paper we examine various tolling schemes for HOT facilities in efforts to identifyrobust pricing policies. The expected performance and corresponding variability of thefacility is evaluated under each pricing scheme for different demand profiles.The focus of this paper is on non-correlated demand uncertainties (i.e. the number ofarrivals during a given time interval is independent of the number of arrivals in the precedingand following time intervals), which we model by considering the number of arrivals in eachminute as independent random variable with known distribution and time-of-day dependentmean. The performance model for a given demand realization is deterministic.The results show that a fixed toll can achieve about two thirds of the benefit of an idealHOT system. The performance of a pre-scheduled toll system is between the fixed toll andthe ideal system: closer to the ideal when the coefficient of variation is below 40%, andcloser to the fixed toll otherwise. A relatively simple real-time system, with density-basedlinear adjustment to the pre-scheduled toll, has practically equivalent performance to the idealsystem.