Upward or downward mobility? Unpacking the impact of subway development on residential relocation using mobile data

The introduction of urban rail stations often transforms the local built environment, potentially disrupting existing residential equilibria and triggering mobility among residents. While such infrastructure may enhance residential quality for those who remain in place, the outcomes for individuals who relocate as a result of these changes remain underexplored. This study addresses this gap by examining Shenzhen’s rapidly expanding rail transit system to assess whether the opening of new subway stations induces residential moves that improve or deteriorate residential quality. Focusing on both in-movers to and out-movers from neighborhoods surrounding new stations, we classify 2.8 million relocation events captured through mobile signaling data into upward, downward, and substitute moves using principal component analysis and support vector machine algorithms. Our difference-in-difference models show that the opening of new subway stations results in a significant 3.7% increase in downward moves among out-movers of nearby neighborhoods, experiencing notable declines in residential quality. At the same time, upward moves among in-movers, which are associated with substantial residential improvements, rise by a similar percentage. Notably, downward moves of out-movers occur before upward moves of in-movers following the station openings, with both patterns being more pronounced in the central area. These findings, based on large-scale longitudinal mobile data, provide detailed insights into how subway development affects residential mobility. They highlight the need for policies to support those at risk of residential decline and promote evidence-based transit-oritented development planning.