​A traffic model or travel demand model (TDM) is a tool used to make traffic forecasts, to test alternative transportation concepts, and to evaluate transportation systems. TDMs are built using a specialized process based on mathematical equations and intensive data collection. TDMs use special software such as TransCAD or MinUTP along with sets of programs that comprise the actual traffic model. A typical TDM will have 10-100 input files and several output files.

Microsimulation models are used in the planning, evaluation and design of transportation project alternatives. They simulate the movement of individual vehicles. Video files from the models can be used to demonstrate project alternatives to the public or key decision makers. 

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​FHWA Traffic Analysis Tools
Numerous traffic analysis tools have been developed by public agencies, research organizations, and private vendor/consultants. Traffic analysis tools can be grouped into the following categories: Sketch-Planning Tools, Travel Demand Models, Analytical/Deterministic Tools, Traffic Signal Optimization Tools, Macroscopic Simulation Models, Mesoscopic Simulation Models, and Microscopic Simulation Models.
FHWA Traffic Analysis Tools