Abstract:Urban interrupted flow travel time probability distribution models are presented based on conventional travel time unimodal distribution. Six types of bimodal probability distributions which apply normal distribution and lognormal distribution as typical distribution are modeled. The parameters of those models are calibrated by Least Square(LS) and Frank Wolfe algorithm. The study results demonstrate that bimodal distributions, in comparison with unimodal distribution, can fit the real data better and highlight the features of interrupted flow. The research contributions can provide an update link cost definitions for path finding in urban network. Meanwhile, the update link travel time probabilistic function can be studied for traffic assignment based on these contributions.