Public transit infrastructure policy improves older adult health by increasing physical activity (walking to and from stations), reducing social isolation through enhanced mobility, and improving access to healthcare and community resources. 

 

This study leverages a natural experiment created by the opening of a new metro line in Hong Kong in June 2021. The new line comprises eight stations: four were newly constructed, and the remaining four were modifications of existing stations (adding platforms, exits, and transfer connections). Treatment groups were defined as residents of areas that received new metro stations. Control groups were residents of areas where metro stations had been operational for more than 15 years. Using a difference-in-differences (DID) approach, we estimated the causal effects of new public transit infrastructure on older adults' physical activity by comparing changes between treatment and control groups, thereby enabling robust causal inference.

 

From a policy perspective, investments in public transit are not merely transportation interventions; they are population health interventions that can reduce healthcare costs, delay functional decline, and improve quality of life for aging populations.

 

Data were sourced from the Metro and Elderly Health in Hong Kong study (PI: Guibo Sun).