A Shortest Path Problem in an Urban Transportation Network Based on Driver Perceived Travel Time


Department of Civil Engineering,Sharif University of Technology


This paper proposes a method to solve shortest path problems in route choice processes when
each link's travel time is a fuzzy number, called the Perceived Travel Time (PTT). The PTT is a subjective
travel time perceived by a driver. The algorithm solves the fuzzy shortest path problem (FSPA) for drivers
in the presence of uncertainty regarding route travel time. For congested networks, the method is able to
nd the shortest path in terms of perceived travel time and degree of saturation (congestion) along routes
at the same time. The FSPA can be used to support the fuzzi cation of trac assignment algorithms. The
applicability of the resulting FSPA for the trac assignment was tested in conjunction with incremental
trac loading and was applied to a large-scale real network. The results of the trac assignment based on
the FSPA, User Equilibrium (UE) and a stochastic loading network model (Dial's assignment algorithm)
were compared to the observed volume for certain links in the network. We conclude that the proposed
method o ers better accuracy than the UE or Dial's assignment algorithm for the network under testing.