A THIRD ROUTE CHOICE ALTERNATIVE FOR THE STOCHASTIC USER EQUILIBRIUM MODEL

The stochastic user equilibrium (SUE) principle was suggested by Daganzo and Sheffi (1977) more than forty years ago to relax the perfect knowledge assumption of network travel times of the deterministic user equilibrium (DUE) model. It is defined as follows: “At SUE, no motorists can improve his or her perceived travel time by unilaterally changing routes”. Specifically, a random error term is incorporated in the route choice decision process to simulate travelers’ imperfect perceptions of network travel times, such that they do not always end up picking the minimum travel time route. In the SUE research, two models dominate the literature. The logit SUE model, based on the Gumbel random error term, has a closed-form solution, but it suffers two major drawbacks (i.e., inability to account for overlapping (or correlation) among routes and inability to account for perception variance with respect to trips of different lengths). On the other hand, the probit SUE model, based on the normal random error term, does not have the two drawbacks, but it lacks a closed-form solution. In this seminar, I will present: (1) a third alternative using the Weibull distribution as the random error term to obtain a closed-form probabilistic route choice model, (2) a weibit-based SUE model that can account for both route overlapping and route-specific perception variance problems, (3) several extensions including the weibit-based model with elastic demand, the weibit-based model with combined mode and route choices, the hybrid logit-weibit SUE model, and the stochastic assignment paradox analysis between the logit and weibit models, and (4) some recent developments on the SUE models.

Dr. Anthony Chen is a Professor in the Department of Civil and Environmental Engineering at the Hong Kong Polytechnic University (PolyU) in Hong Kong. Prior to joining PolyU, Dr. Chen was a Professor in the Department of Civil and Environmental Engineering and Head of the Transportation Division at Utah State University in the United States for seventeen years. Dr. Chen was a recipient of the prestigious Faculty Early Career Development (CAREER) Award from the National Science Foundation (NSF) in 2002 and the Chang Jiang Chair Professor from China in 2015. Dr. Chen is currently serving as an associate editor for Transportmetrica A: Transport Science, Networks and Spatial Economics, and Journal of Advanced Transportation, and an editorial board member of Transportation Research Part B: Methodological.