Increasing congestion is one of the most important challenges facing transportation professionals across the nation. Increasing road capacity by adding lanes is one of the solutions to the challenge of meeting increasing road demand. However, this suffers from the problem of “triple convergence”, as noted by Anthony Downs in “Stuck in Traffic”. Relatively low price related to the usage of expensive new capacity encourages more users to drive the expanded roadway. Congestion pricing is one of the tools available to address triple convergence. In addition, a region designated as non-attainment area for ozone must ensure any proposed single occupancy vehicle capacity additions are compatible with the region’s air quality goals. Congestion pricing is one of the congestion management strategies that can also help with meeting air quality goals. However, timing of the implementation of congestion pricing needs to be carefully analyzed and planned. Triggers need to be developed and implemented for congestion pricing during early stages of operation or prior to the opening of the roadway to gain the full benefits.

Toll diversion models can be used in developing appropriate triggers for consideration of congestion pricing implementation on traditional toll roads based on selected performance measures. For example, by using level of service (LOS) as a performance measure, a preliminary congestion pricing regime (PCPR) can be triggered at LOS D and an aggressive congestion pricing regime (ACPR) can be triggered at LOS E. As part of this work, results of a case study will be presented where, for a selected performance measure, various pricing schemes under PCPR and ACPR will be tested to determine the traffic, revenue and other performance impacts. In addition, triggers for lane expansion will also be determined under a selected pricing and performance measure combination. This presentation will also include a suggested process for implementation of congestion pricing strategies, monitoring and reporting, triggers for congestion pricing and capacity expansion, etc.

The lessons from this analysis can help transportation and toll agencies in developing plans to better manage congestion on their existing facilities and in planning for future expansions.