TRANSYT 7F has
two delay-based traffic models: link-based and step-based. The original link-based model works
well for undersaturated traffic conditions. It has been extensively validated by users all over the
world and accepted as a sound model. Recently, the program developers added the step-based
model to remove the limitations of the first model. This model takes into consideration the
formation and dissipation of queues in space. In addition, it accounts for flow interactions on
adjacent links through a step-by-step analysis of all links in the system. Conceptually, this
model is better suited for the analysis and optimization of congested (oversaturated) facilities.
Consequently, it also requires more computation time.