Transportation Planning and TRANSIMS Microsimulation Model: Preparing for the Transition

The Transportation Analysis and Simulation System (TRANSIMS) was developed as a replacement for the four-step travel demand model. The goal was to provide a simulation system that could analyze issues facing transportation planners such as sustainable development, environmental impacts of proposed projects, and intelligent transportation systems deployment. Because TRANSIMS represents a significant shift from the current state of the practice, the transportation planning community will need to spend significant human and capital resources preparing for the transition. Some insight into these transitional issues is provided on the basis of lessons learned from research on actual calibrated transportation networks in Texas. An overview of TRANSIMS in terms of its main components along with a brief comparison with the four-step model are supplied, followed by a discussion of the data requirements with specific reference to the current data needs associated with the four-step model. The challenges inherent in converting databases that have been developed for four-step models are also discussed on the basis of the conversion of existing traffic network files. Next, the TRANSIMS traffic flow theory is described, and the challenges for transportation planners are illustrated using calibrated networks from two highway corridors in Houston, Texas, and one diamond interchange network in College Station, Texas. Last, the capabilities of TRANSIMS with respect to output analysis are described.