Long commuting, social inequality, and urban development with scaling laws in China

Long commuting is associated with negative consequences on the environment, economy, society, and ultimately on urban sustainability. It is still unclear to what extent long commuting, one of the most frequent daily activities for urban dwellers, can be explained with scaling laws. In this paper, we examine whether the number of people suffering from long commuting (LC) disproportionately grows as the city size (population) increases. We employ a census dataset of 811,452 participants, covering details of individual commutes and socioeconomic background in 288 cities in China. By identifying the most sensitive threshold of commuting time, this paper defines commute no less than 60 minutes as LC and explores the scaling laws accordingly. We find that there is a strong super-linear relationship in cities with more than 1.3 million people, suggesting that there exists an optimal city size from the perspective of commuting efficiency. For cities with more than 1.3 million people, this paper reveals that a 1% increase in the population of a city implies an increase of 1.57% in the number of commuters with LC. According to our model calculation, in 2022, the number of long-time commuters in cities with population over one million was 19.06 million in China. With the investigation of various urban attributes and LC, we conclude that mega-cities or above tend to have more LC, the more LC. Moreover, we find that long commuting can reflect on social inequality about gender, income, education, and housing issues, which can offer policy implications for future urban sustainability.