Extending the theory of planned behavior: Predicting the use of public transportation

An expanded version of the theory of planned behavior (TPB) was used to predict and explain public transportation use. A pre-post design was used to examine changes in university students' bus ridership after the implementation of a universal bus pass (U-pass) program. Bus ridership significantly increased after the U-pass was implemented, and associated changes in attitudes and beliefs about transportation modes were found. In both phases, students' public transportation use was well predicted by the original TPB. However, 2 additional constructs-a descriptive norm, and the interaction between intention and perceived behavioral control-significantly improved prediction in both phases of the study. These constructs might be useful additions to the original TPB, at least in this behavioral domain.