Using a Simulation Environment for Dynamic Toll Analysis

The Capital Beltway HOT Lanes will be a 14 mile subset of the Washington, D.C. region‟s Capital Beltway (Interstate 495) upon completion in December 2012. Buses, carpools (HOV3+), motorcycles and emergency vehicles will be able to access the Capital Beltway HOT lanes for free while drivers with fewer than three occupants must pay a toll to use the HOT lanes. Upon opening, they will be among the most advanced variably priced toll lanes in the world. A dynamic toll algorithm (DTA) will be responsible for making adjustments to the toll prices at regular intervals based on measured traffic density. An effective means to examine, develop and test the toll system capabilities prior to implementation was considered essential. A very limited number of real-world algorithms currently exist for dynamic pricing on toll roads, and none was currently available in any existing simulation environment capable of accurately reflecting the fully dynamic nature of the Beltway‟s HOT Lanes toll system. After evaluating various options, the eventual selection of Caliper Corporation‟s TransModeler was made as the package of choice. A new and distinctive micro-simulation traffic environment was created based on the MnPass algorithm and used in the dynamic tolling analysis for the project. The simulation analysis was undertaken in the system procurement phase of the project to allow for integrated testing activities concurrent with the design and development process, which will yield significant positive outcomes for the project.