Does metro expansion matter? Metro network enhances metro mode share of commuters living away from stations, but not those near stations

As the metro system grows from a single line to a network of multiple lines, how does the expansion affect metro mode share of commuters residing near and away from stations? This study attempted to uncover the mechanism of commuters' mode choice after the expansion. We employed two waves of household travel survey data, before and after the formation of the metro network in Xi'an, to develop a difference-in-difference model. We found that after the metro network formed, the average metro mode share of residents within 1 km of metro stations increased slightly but the change was statistically insignificant. This is because the average share was smaller around the stations of newer metro lines. By contrast, the average metro mode share of residents living beyond 1 km from metro stations grew substantially, likely because of the increase of workplaces within station areas and the improvement in first-/last-mile connection services. To achieve low-carbon transport, this study underscores using metro lines to connect key destinations, densifying employment around metro stations, and promoting access to metro stations through convenient feeder buses, shared micro-mobility, and pedestrian-friendly design.