Intro to Modeling

Caltrans and the MPOs in California operate and maintain Travel Demand Models (TDMs) that are intended to forecast demand ( e.g. volumes) and performance ( e.g. speeds, etc.) on transportation networks. Some counties also operate TDMs. Those counties are generally within multi-county MPOs that are not able to provide sufficient geographic detail in their MPO Travel Demand Models.

TDMs typically produce their forecasts by creating trip tables of demand that can then be assigned to transportation networks. The topics presented are intended to provide a general overview into the modeling process followed in these TDMs.