Modeling the equilibrium bus line choice behavior and transit system design with boundedly rational users Chuan-Lin Zhao, Hai-Jun Huang School of Economics and Management, Beihang University, Beijing 100191, China chelone@163.com Abstract: In the most transportation literature, travelers are assumed to be perfectly rational in minimizing their own travel costs or perceived travel costs. However, users may be not perfectly rational to find their optimal choices in reality. This paper examines the effect of boundedly rational users on the bus line choice behavior. This kind of users makes the satisfied choices. Specifically, the following questions are investigated: How do the boundedly rational users affect the equilibrium bus line choice behavior? How to design the more realistic public transport system when considering the boundedly rational users? Keywords: equilibrium; bus line choice; bounded rationality; transit system design 1. Introduction The purpose of this paper is duple: to advance our understanding of the boundedly rational behavior of public transit users when choosing a bus line in a transit network, and to design a more realistic public transit system when considering the boundedly rational users. In the literature, user equilibrium models play an important role in the traffic assignment problems. By assuming all road users behave in a completely rational way and seek to minimize their own disutility, Wardrop [1] defined a state of route choice, so-called user equilibrium (UE). At the UE state, no user can further improve her or his utility by unilaterally changing routes. By relaxing some of the behavioural restrictions implied in a strict deterministic disutility minimization rule, Daganzo and Sheffi [2] developed a stochastic user equilibrium (SUE) model that considers the travellers’ imperfect perceptions of travel times. The SUE is achieved when users can no longer change their perceived utility. Existence and uniqueness of UE or SUE in general networks have been well investigated in the literature, including the solution methods for obtaining these two states, see Sheffi [3], Yang and Huang [4] for more