Heterogeneous Effects of Road Network Structure Characteristics on Household Carbon Emissions for the Western Valley Cities in China

Understanding how urban road network structures influence household carbon emissions is fundamental to developing low-carbon urban environments. This study examines China’s Western Valley cities (WVCs), which have distinct structural characteristics, to analyze the heterogeneous effects of road network structures on household carbon emissions. Using 2020 household carbon emissions and road network data, we employed stepwise regression and curve estimation regression models to clarify these relationships based on the distribution patterns of both variables. The following are the key findings of this study: (1) Substantial differences exist between cities in terms of total household carbon emissions, per capita emissions, and per capita land use. (2) Regarding road network structure, cities can be categorized into three types—clusters, fingers, and belts—based on the distribution of high and low values of closeness centrality (CC), with four, five, and six cities falling into each category, respectively. While compactness differences between cities are relatively small, variability exhibits large disparities, leading to different city rankings and highlighting the complexity of road network organization. (3) The three structural characteristics show significant correlations with household carbon emissions not only in terms of direction but also magnitude and influence mechanisms. (4) CC follows an inverse function pattern, initially declining sharply before gradually stabilizing. Compactness follows a positive linear growth pattern, consistently promoting household carbon emissions. Variability exhibits a positive power-law growth pattern, showing a sharp initial increase that weakens over time.