Does urban rail transit network expansion lead to more extreme commuting?

Extreme commuting, usually defined as commuting over exceptionally long distance or time, is becoming increasingly common and gaining attention for its severe impacts on the well-being of extreme commuters. Numerous studies have been conducted to investigate the determinants of extreme commuting. Not much research attention has been paid to the changing trends of extreme commuting, especially in the context of urban expansion and transport infrastructure developments. This study aims to address this research gap by examining the evolving trends of extreme commuting Shenzhen, China, a city that has experienced rapid urban expansion and transport development over the past decades and witnessed the development of a rail transit network from scratch to more than 450 kilometers in nearly two decades. We are particularly interested in the following research question: does the rail transit network expansion lead to more extreme commuting? We use data from Shenzhen’s periodical household travel surveys and employs the difference-in-differences modeling framework facilitated with flexible machine learning models to identify the potential the causal effects of transit network expansion on extreme commuting. The preliminary results show that commuting distances have increased, but commuting times seem to be rather stable. The findings of this research shall contribute to the knowledge on extreme commuting with a dynamic perspective and the role of rail transit in extreme commuting.