From car to rail: Two phases of modal shift following metropolitan railway launch and network integration. Repeated cross-sectional evidence 2017–2025

Encouraging a shift from private cars to public transport is a key objective of sustainable mobility policy, yet evidence on how modal shift evolves over time following rail investments remains limited. This study examines changes in self-reported reductions in car use among passengers of the Pomeranian Metropolitan Railway (Poland) using five waves of repeated cross-sectional surveys conducted between 2017 and 2025 (N = 2347). We distinguish between two phases of system development: the initial railway launch (2017–2020) and subsequent network integration (2021–2025). Temporal trends were analyzed using repeated cross-sectional methods, propensity score matching, structural break tests and pooled regression models. Theory of Planned Behavior analysis was used to explore behavioral mechanisms in the most recent survey wave. Results reveal a two-phase pattern of modal shift. During the launch phase, approximately one quarter of passengers with car access reported reducing car use, with no significant changes across survey waves. Following network integration, this proportion increased to over one half and remained similarly stable, with no statistically significant difference between the two integration-phase waves. Perceived behavioral control emerged as the strongest psychological correlate of modal shift intentions. The findings indicate a substantial phase-level difference in self-reported car-use reduction, with higher levels observed during the integration phase. The results suggest that changes in network integration may be associated with higher levels of reported car-use reduction. By distinguishing between launch and integration phases, the study contributes new long-term repeated cross-sectional evidence on how metropolitan rail systems influence travel behavior over time.