The paper summarizes the recent application of an ABM for highway pricing studies in the Chicago metropolitan region. The region currently has toll facilities that allow for statistical analysis and estimation of impacts of congestion and pricing on travel demand. The Chicago Metropolitan Agency for Planning (CMAP) recently explored a wide range of new pricing schemes that provided extensive material for model sensitivity testing. Specifically, CMAP explored a scenario where all new highway capacity recommended by the GO TO 2040 long range plan was priced to eliminate delay for all times of day. Results indicated that congestion pricing on new capacity reduced delay on priced managed lanes, non-priced lanes, and also neighboring arterials. These benefits are achieved with toll rates that are very similar to tolls on existing congestion priced roads across the United States. Additionally, the peak period tolls do not turn away significant numbers of low income users.

The paper also contains a discussion of the model structure which is organized by the following main topics:

• User segmentation in the demand model and highway network procedures. One of the primary advantages of a microsimulation ABM is the high degree of population and travel segmentation. In aggregate network simulations, a parallel level of segmentation was supported in multi-class assignments.

• Distributed Value of Time (VOT) and other behavioral parameters. Within each segment, willingness to pay is subject to a significant variation across individuals and situations. The microsimulation ABM framework allowed for an effective randomization of VOT as well as other parameters across individual agents within the same segment.

• Time-of-day choice with a fine temporal resolution. Modeling impacts of congestion and pricing, such as peak spreading, requires a level of temporal resolution of 30 minutes or less.

• Vehicle occupancy is a very important factor that affects willingness to pay and eligibility to use Managed Lanes (HOV/HOT lanes). The Chicago ABM incorporates an explicit modeling of joint travel as a separate travel segment.

• Route type choice integrated with mode choice was implemented as opposed to the all-or-nothing route choice framework embedded in a deterministic traffic assignment.