Does street network design affect traffic safety?

  • Published: Accident Analysis and Prevention, Volume 43(3):769-781, 2011
  • Authors: W.E. Marshall and N.W. Garrick
  • Date Added: 18 Apr 2013
  • Last Update: 18 Apr 2013
  • Format: pdf

Objectives:

Assess the effect of street and street network characteristics on total RTIs, severe injury RTIs, and fatal RTIs.

Methodology:

Negative binomial regression models were used to assess the effect of street and street network characteristics on total RTIs, severe injury RTIs, and fatal RTIs. Data from over 230,000 RTIs taking place over 11 years in 24 California cities was analyzed at the U.S. Census Block Group level of geography.

Key Findings:

  • The findings suggest that for all levels of RTI severity, street network characteristics correlate with road safety outcomes. Denser street networks with higher intersection counts per area are associated with fewer RTIs across all severity levels. Conversely, increased street connectivity as well as additional travel lanes along the major streets correlated with more RTIs.

  • The results suggest that in assessing safety, it is important to move beyond the traditional approach of just looking at the characteristics of the street itself and examine how the interrelated factors of street network characteristics, patterns, and individual street designs interact to affect RTI frequency and severity.

  • Increasing the percentage of Citywide Streets with on-street parking was associated with more total RTIs and severe RTIs, but there was no significant association between on-street parking and fatalities.

Themes:

On-street parking, Road traffic incidents, Assessing safety.

Comments:

Useful research but only limited reference to parking, there is no explanation why on-street parking was associated with more total road traffic incidents.

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