DEVELOPMENT AND APPLICATION OF A REGIONAL TRAFFIC SIMULATION AND DYNAMIC TRAFFIC ASSIGNMENT MODEL FRAMEWORK
Ramachandran Balakrishna, Caliper Corporation
We present a first-of-its-kind methodology integrating large-scale, lane-level microscopic traffic simulation, dynamic traffic assignment (DTA) and a travel demand model. We further describe the operational details involved in implementing the framework in the real world, in a dense, urban region spanning over 500 square miles and six towns and cities. The model, carefully calibrated against 15-minute link and turn count data, was subsequently validated to speed data. We demonstrate the practical use of such a detailed model by analyzing a future build scenario, thus illustrating the immediately realizable benefits and value derived from such an exercise. We present computational evidence to prove that such high-fidelity regional models are practical with current computing capabilities.
Maricopa Association of Governments
As the focus of transportation systems management moves increasingly toward strategic management of the system’s capacity and away from building new capacity, transportation planners are faced with questions that fall outside the scope and predictive powers of conventional travel demand models. To equip planners with the means to address those questions, a number of modeling approaches and methods has been proposed. Commonly, traffic simulation and dynamic traffic assignment are among the proposed solutions. However, not so commonly is the marriage of either traffic simulation or dynamic traffic assignment (DTA) with travel demand modeling found in application. This paper outlines an approach to marry the three – traffic simulation with dynamic traffic assignment with travel demand modeling – in one framework for application to project prioritization. The Central Phoenix, Arizona region is used to prove the feasibility and value of such a detailed, large-scale, dynamic model that has been well-calibrated to field data measured at a fine temporal resolution.
The Central Phoenix study area is enclosed by the Inner Loop 101 highway, covers over 500 square miles, and contains more than 1,800 signalized intersections. The spatial extent includes six towns and cities. The model represents the first application of its kind – calibrated and validated microscopic traffic simulation and microscopic traffic simulation-based DTA for a very wide area. The model includes auto and truck travel and schedule-based bus and light rail operations on more than 90 local and express routes. The model was calibrated to 15-minute directional and turning movement counts and validated against 15-minute speed data obtained from Inrix. The validated model also serves as a geographically accurate inventory of the transportation infrastructure (e.g. sensor locations, signals) as well as its associated data (e.g. traffic counts, speeds, signal timing plans) from numerous sources.
We present the overall framework in the form of a case study of Central Phoenix, highlighting the core components of the model – a microscopic traffic simulation model, a microsimulation-based DTA model, and the interface with the regional travel demand model – and detailing their calibration and validation. We trace the model development, calibration, and validation steps as a template for applying a similar framework in other cities. We also discuss key challenges associated with such large-scale, regional model deployments from the data availability, model calibration and computational perspectives. Lastly, we demonstrate the model’s utility in an application, simulating a future-year build-out scenario and presenting numerous performance measures. This work advances the state of the art, while simultaneously extending the state of the practice by allowing agencies to answer intricate policy sensitivity questions using affordable desktop hardware.
Association for European Transport