The causal effect of monthly pass programs on public transportation and carbon emissions
Document Type
Journal Article
Publication Date
2025
Subject Area
place - asia, place - urban, mode - subway/metro, ridership - behaviour, ridership - growth, technology - emissions, technology - ticketing systems
Keywords
monthly pass program, carbon emissions
Abstract
While existing research has examined the relationship between monthly pass and public transportation usage, limited attention has been given to their effects on carbon emissions. This paper evaluates the impact of a monthly pass program in the Taipei Metro system on travel behavior. Using administrative origin–destination records and a difference-in-differences method, we find that the program increased metro ridership, passenger kilometers, and trip value by 4.3%, 4.6%, and 4.6%, respectively. The effects are more pronounced for trips occurring on weekends, during peak hours, and at stations located near schools, residential areas, and business districts. Moreover, a larger effect of the program is found at higher ticket prices. Estimates of a back-of-the-envelope calculation suggest that the program delivers negative overall carbon emissions as long as at least 70–80% of the increased metro usage was shifted from trips previously made by private cars or motorcycles.
Rights
Permission to publish the abstract has been given by Elsevier, copyright remains with them.
Recommended Citation
Liou, Y. Y., Kim, M. K., Chang, H. H., & Liou, R. W. (2025). The causal effect of monthly pass programs on public transportation and carbon emissions. Transportation Research Part D: Transport and Environment, 146, 104903.

Comments
Transportation Research Part D Home Page:
http://www.sciencedirect.com/science/journal/13619209