Identifying disparities in the relationship between neighborhood walkability and active transportation safety within South Carolina

Abstract

Background

Active transportation crashes are of great concern in the Southeast U.S., especially within disadvantaged neighborhoods with poor infrastructure. Little research has evaluated how characteristics of the built environment are associated with active transportation safety, or how this association may differ by neighborhood disadvantage. This study examined the relationship between neighborhood walkability and pedestrian and cyclist crashes, including variations by social vulnerability across census tracts in South Carolina (SC).

Methods

Four key variables were collected for each census tract in SC (N = 1103): walkability, pedestrian and cyclist crashes, and social vulnerability. The Environmental Protection Agency's National Walkability Index (NWI) scores were averaged across block groups to determine walkability per tract. Pedestrian (N = 10,689) and cyclist (N = 4802) crash count and severity were obtained from SCDOT [2011–2021], aggregated per tract, and adjusted for average trips per day. Social vulnerability, the degree of susceptibility of a community to hazards, was measured by the Centers for Disease Control and Prevention, Social Vulnerability Index (SVI); higher percentile rankings indicate greater SV. Hierarchical linear regressions were conducted to determine the relationship between walkability and pedestrian and cyclist crash count and severity, including moderation by SV.

Results

Across all SC census tracts, there was a significant, negative relationship between walkability and pedestrian and cyclist crash count (b = −0.005,SE = 0.001; b = −0.020,SE = 0.003) and severity (b = 1.073,SE = 0.193; b = −2.831,SE = 0.492) per trip. Further, greater walkability within tracts at high compared to low SV levels, was especially associated with fewer and less severe crashes.

Conclusion

Worsened walkability was associated with greater and more severe active transportation crashes, significantly varying by SV. These findings help identify neighborhoods in SC in need of infrastructure improvements to address active transportation safety, thereby facilitating greater physical activity and reducing chronic disease.