A methodological framework to conduct joint zone-based analysis of traffic safety and accessibility

Increasing accessibility and improving cycling safety are the primary objectives of cities and policymakers. In the literature, there are several studies examining cycling safety and few studies examining cycling accessibility. However, few studies conduct a joint examination of these two topics to understand the relationship between them. This paper aims to develop and apply a methodological framework to conduct a joint zone-based analysis of traffic safety and accessibility. The developed framework integrates route choice modelling and four-step modelling into traffic safety and accessibility analysis and the outcome is a novel zone-based crash risk estimation incorporating traffic crashes with trip characteristics (including, trip purpose, origin-destination, and alternative routes). The proposed framework was applied in a case study to examine the injury crash risk imposed on commuting cyclists and job accessibility in the city of Utrecht, the Netherlands. The results illustrate the need to embed trip characteristics into zone-based traffic safety estimation to be able to compare the spatial distribution of traffic safety with other mobility and transport-related indicators. Moreover, the findings reflect on significance of taking route choice features into account in accessibility analysis to avoid overestimating accessibility levels. They show that safety and accessibility levels are not equally distributed in the city of Utrecht. For example, low-income areas generally have lower job accessibility levels and higher cycling crash risks which imply the spatial and social inequalities in the transport system's effects.