A fuzzy traffic assignment algorithm based on driver perceived travel time of network links

Traffic assignment is a step of travel demand estimation. given a trip origin–destination demandmatrix, this step determines traffic flow in each link, according to assumptions based on the behaviorof drivers. conventional assignment algorithms, which are mostly based on the wardrop first principleof user equilibrium, assume that all drivers choose the shortest path to the destination, based on thesame travel time computed by travel time functions. however, in reality, driver perception of travel timevaries for a specific route. this paper presents a traffic assignment algorithm which assumes that driverperception of travel time affects route choices. fuzzy set theory is used to define travel time perceived bydrivers. a fuzzy equilibrium is suggested for the prediction of network flows. next, a fuzzy incrementaltraffic assignment algorithm (fita) is developed to utilize route perceived travel time (ptt) for reachingthe suggested fuzzy equilibrium. the fita is used for a real network traffic assignment in mashhad, whichis large city in iran. traffic flow that is estimated by a fita and by conventional algorithms is comparedto real observed volumes, which indicate that a fita is more accurate than conventional traffic flowestimation algorithms.