The need to calculate the shortest route that minimizes actual experienced travel time (in
lieu of the shortest route that minimizes travel time based on some snapshot measurement of link
travel time) motivated the development of time-dependent shortest path (TDSP) algorithm. (In
transportation network modeling literature, the term “path” is mostly used as path is formally
defined in general graph theory. However, throughout this document the term path is only used
in the context which relates to literature in which path is used. In other general descriptions, the
term route is used.) More discussions of the difference between the two types of shortest path
algorithms are presented in the section on Instantaneous and Experienced Travel Times.