Fuzzy route choice model for traffic assignment

In order to represent traffic assignment on a road network, we propose a new route choice model taking account of the imprecisions and the uncertainties lying in the dynamic choice process. This model makes possible a more accurate description of the process than those (deterministic or stochastic) used in the literature. We assume that drivers choose a path all the more than it is foreseen to have a lesser cost. The predicted cost for each path is modelled by a fuzzy subset which can represent imprecision on network knowledge (e.g. length of links) as well as uncertainty on traffic conditions (e.g. congested or uncongested network, incident...). The costs of all possible paths are compared and result in an attractiveness degree for each path. Various comparison indices can be used to represent the different possible natures of drivers when making their decisions (pessimistic/optimistic, risk-taking/risk-averting). The fuzzy choice model was compared with the LOGIT model (a widely used stochastic discrete choice model) and has been proved to be able to find the same results. The effect of Advanced Travellers Information Systems (ATIS) on drivers is modeled as a modification of the imprecision or the uncertainty of the predicted cost of a route. (C) 2000 Elsevier Science B.V. All rights reserved.