Abstract
In this paper, the mechanism that the modal choice in the outward trip of the round trip constrains that in the return trip and vise versa is characterized as strategic complementarity in modal choice. The positive feedbacks between bus demands and the number of bus operation functions in the bus market, if there exists strategic complementarity in modal choice by households. The market equilibrium model is formulated to investigate the multiplicity of the equilibrium and the impacts of transportation policy, such as car sharing, rental cycles, etc., which is designed to remedy strategic complementarity in modal choice, upon the market equilibrium and social welfare.
