Extending the Theory of Planned Behavior: Predicting the Use of Public Transportation¹

Abstract

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.