The Influence of the Built Environment on Crash Risk in Lower Income and Higher-Income Communities

University Transportation Centers Program2020PDFTech ReportDumbaugh, EricLi, YanmeiSaha, DibakarMerlin, LouisFlorida Atlantic UniversityCollaborative Sciences Center for Road SafetyUnited States. Department of Transportation. Federal Highway AdministrationCollaborative Sciences Center for Road SafetyFloridaUnited StatesTraffic safetyEquity (Justice)Transportation disadvantaged personsLow income groupsUpper income groupsCrash characteristicsTransportation EquityTransportation DisadvantageCSCRS-R11Final ReportThis report presents the findings of a study that uses negative binomial regression models to examine differences in the relationship between the built environment and crash incidence for block groups in Orange County, Florida. It finds notable differences in the modelled variables between these income groupings, both in the magnitude and the direction of effects. First, while urban arterials are a risk factor for lower- and higher-income block groups alike, their negative effect on safety is profoundly greater in lower-income environments. For higher income communities, each additional mile of urban arterial is associated with a 9% increase in total and KAB crashes, though it did not have a statistically meaningful relationship with pedestrian crashes. For lower-income communities, each mile of urban arterial is associated with a nearly 30% increase in total and KAB crashes, as well as a 19% increase in pedestrian crashes. While it is widely presumed that the presence of sidewalks and sidewalk buffers enhance safety, the results of this study suggest that the relationship between these features and traffic safety is more complicated. For more affluent areas, which contain residents who are less dependent on walking as a primary means of transportation, sidewalk buffers were found to be associated with significant increases in total, injurious, and pedestrian collisions alike, while the presence of sidewalks was associated with a significant increase in injuries involving all road users. For lower income communities, sidewalks and sidewalk buffers were not significantly related to increases in crashes or injuries; indeed, the increased presence of these features tended to be associated with reductions in injurious and pedestrian crashes. Finally, race proved to have an important role on crash risk. While the percentage of white residents was not meaningfully associated with crash risk in more affluent block groups, race emerges as an important factor for understanding crash risk in lower-income communities, with higher concentrations of non-white residents being associated with significant increases in total, injurious, and pedestrian-related crashes. This report concludes by discussing the likely causes and broader implications of these findings.140