Changes in the public transit market following the introduction of a new light rail system: A before-and-after study in Montreal, Canada

The introduction of large-scale public transit infrastructure often carries the promise of improving regional mobility, reducing car dependency, and fostering sustainable urban development. However, the success of such investments depends not only on the quality of service delivered but also on how different segments of the population respond to the new mobility option. This study explores the impacts of a major infrastructure project, Réseau express métropolitain (REM) in Montréal, on the public transit market. The REM is a 67-km automated light rail system designed to enhance regional mobility in Montréal, Canada with an investment of more than $9 Billion CAD. We draw on cross-sectional and longitudinal data from the Montréal Mobility Survey in 2022 (before REM operations) and 2024 (after the opening of the South Shore branch). We apply exploratory factor analysis and weighted k-means clustering to identify and track transit user segments over time. Across both waves, a four-cluster solution emerged indicating that the overall market structure remained stable. However, longitudinal analysis revealed significant individual transitions, with many potential REM telecommuters reverting to car-oriented behaviors. These findings highlight the duality of stable market profiles but fluid individual behaviors, demonstrating that new infrastructure can reshape travel patterns within existing markets rather than creating entirely new ones. These findings are of interest to policymakers and transit planners interested in market segmentation to understand behavioral adaptation regarding new LRT infrastructures over time.