Incorporating aggregate behavior in an individual's discrete choice: An application to analyzing illegal bicycle parking behavior

Many types of travel behavior involve positive social interaction (conformity effect) and it sometimes induces undesirable results, such as chronic illegal bicycle parking and illegal car parking. In this study, the conformity effects among bicycle users in the choice problem of bicycle parking locations were modeled and estimated within a discrete choice framework. The proposed model combines discrete choice behavior of bicycle parking locations at an individual level (micro-level) with an average choice at an aggregate level (macro-level). The social equilibrium equation, which is derived from the individual-level choice model, entails multiple equilibria with regard to the choice proportion for each reference group of individuals. The model was econometrically identified by using the data collected in a survey conducted in Tokyo in 2001. The empirical results indicated that large variations in collective behavior occur across subgroups, which were defined by the stations the respondents visit often, since there was an intensive positive social interaction. Finally, the marginal frequency of police patrols required to drastically reduce the level of illegal bicycle parking was also calculated using the identified model.