Tour based travel demand modeling in the US

The premise of this paper is that four-based modeling is a reasonable near-term alternative to the traditional four-step process. Tour based modeling is a step toward activity-based modeling, which treats travel as a demand derived from the desire for activities. Activity-based modeling has a stronger theoretical basis than tour-based modeling. It has the potential to become the next generation of model systems, but it is still not a practical alternative for agencies in the U.S. Tour based models have already been implemented in urban areas and can be further implemented in a short period of time.