Modelling Behavioural Change in a Social Dilemma of Commuters’ Mode Choice

Our research attempts to apply an agent-based approach to modelling travel behavioural change in a transportation system. Utilizing the advantage of agent-based model of being validated at an individual level, a social dilemma situation of travel mode choice is modelled and viewed as a complex system. Behavioural process of individuals is examined in an agent-learning model considering psychological and sociological aspects. A traveller is modelled to have expectations, which shows his beliefs about the influence of his action on other members of the group, as decision making rules. Two classes of beliefs are considered in the model: bandwagon and opportunistic expectations. Social interaction using a group-based interaction is hypothesized to be important to solve the social dilemma. We apply an imitation game based on social learning mechanisms to the traveller model in order to evolve the rules of each traveller. Two kinds of mechanism are used: payoff-biased transmission and conformist transmission. The model revealed that some insightful results could be obtained, such as the conditions that make cooperation as a possible outcome. They are group-based interactions, limited information, and conformist transmission. Emergent phenomenon of the system may favour cooperation and resolve the dilemma of travel mode choice, if a strong conformist transmission presents. This gives an insight to the possibility of solving the social dilemma by incorporating an employer-based Travel Demand Management (TDM) measure.