Decomposing neighborhood disparities in bicycle crashes: A Gelbach decomposition analysis

Despite growing evidence showing significant spatial disparities in bicycle crash rates within a city, little research has explored their contributing factors. Focusing on Seoul, South Korea, this study examines whether differences in bicycle crash rates between neighborhoods with low and high socioeconomic status (SES) exist, and if so, which and to what extent the observable neighborhood characteristics explain them. This study adopts the Gelbach decomposition method to illuminate the sources of bicycle crash disparities between neighborhoods with different SES. Results indicate that bicycle crashes are more likely to occur in low-SES neighborhoods, regardless of injury severity. However, contrary to popular expectations, the differences in bicycle infrastructure or bicycle traffic volume between high- and low-SES neighborhoods do not significantly contribute to the gaps in bicycle crash outcomes between neighborhood types. Instead, the differences in population density and road networks based on neighborhood SES are the primary drivers of these gaps. Another notable finding is that the neighborhood-level factors included in the analysis can altogether explain less than 50% of the disparities in bicycle crashes between neighborhood types. The findings of this study provide valuable policy suggestions that help address spatial equity related to bicycle crashes.