As part of a consultant team working on a feasibility study of a new toll road in the Chicago region, Parsons Brinckerhoff recently used an activity-based model to prepare estimates of travel demand and toll revenue. The proposed road is in a high growth, high congestion area that also has a sensitive natural environment. Given these conditions, the client and the local planning community wished to explore a wide variety of tolling scenarios well suited to testing with an advanced activity-based model. The client and the consultant team worked with the Chicago Metropolitan Agency for Planning (CMAP) to make use of their Pricing Model, an activity-based model of the CT-RAMP (Coordinated Travel and Regional Activity Modeling Platform) family, developed in 2011. The model system generates individual and joint tours with all details of tour structure, destination, mode, and time of day using a series of discrete choice models estimated from CMAP’s recent household travel survey. These tours are converted into person and vehicle trip tables and assigned to a regional highway network in EMME using route choice and multi-class assignment procedures segmented by 8 time of day periods.
For the current project, the model system was specifically validated and calibrated within the study area. The model system was used to evaluate numerous combinations of road configuration and tolling policies, including time of day pricing, variable speed limits, indexing tolls to inflation, pricing of existing free roads, and revenue maximizing toll rates. The presentation will feature detailed discussion of the model structure, its sensitivity to various travel choices, the practicalities of applying an activity-based model for a project study, and the impacts of pricing. The overall conclusion is that an activity-based model is a very useful tool for traffic & revenue studies that allows for many important types of analysis that would have been very difficult to implement with a 4-step model.