Street network types and road safety: A study of 24 California cities

Abstract

This article examines the role of the street network in road safety outcomes. Data on more than 130 000 crashes occurring over 9 years in 24 medium-sized California cities was input into a geographic information system (GIS) and evaluated against principal measures of street network density and connectivity at the Census Block Group level. Few studies have taken this more comprehensive approach of looking at the complete street network when it comes to safety, partly because until now this kind of holistic assessment would have been very difficult without recent advances in research tools such as GIS. The results of this study suggest that street network characteristics do in fact play a role in road safety outcomes. Although the underlying factors contributing to this role are not yet known, our analysis showed safety outcomes to be associated with street network density. More specifically, our results indicate that the highest risk of fatal or severe crashes occurs with very low street network density and safety outcomes improve as the intersection density increases.