Examining Attribution of Fault in Fatal & Serious Injury Crashes between Drivers and Vulnerable Road Users
Project Description
Traffic crashes killing or severely injuring pedestrians and bicyclists have increased dramatically in the past 10 years in the US. Research has found media and police narratives to play a strong role in shaping public opinion around strategies to prevent crashes involving vulnerable road users (VRUs), including whether those narratives attribute blame to the VRU victim. In California, following a crash, data are collected by law enforcement officers who make a determination of the “party most at fault.” Concerns exist as to whether fault in crash report data is over-attributed to VRUs, but no systematic research has assessed this.
We will utilize 2016-2023 electronically reported California Crash Reporting System data to identify the presence of a crash witness at each fatal or serious injury (FSI) single-vehicle/VRU crash, under the hypothesis that fault is more accurately attributed when a witness is present. Because VRU victims involved in FSI crashes with a motor vehicle are often unconscious, in transport to a hospital, or deceased at the time of the crash investigation, only the driver’s perspective is incorporated into police reports in the absence of a witness, while the presence of a witness provides additional and, we hypothesize, more objective information. The specific research question is: is the presence of a witness associated with a higher probability that the driver will be named at fault in FSI crashes between a driver and a VRU compared to crashes between a driver and a VRU when no witness is present?
We will use logistic regression to estimate the probability of the driver being attributed fault in crashes where a witness was present compared to crashes with no witness. If the probability is higher when a witness is present, we will discuss the likelihood that this implies that fault is systemically over-attributed to the VRU when there is no witness vs. other explanations. We will control for neighborhood and investigate if the effect of a witness on attribution varies according to reporting agency, victim attributes, or victim mode. The overall goal will be to estimate minimum correction factors and 95% confidence intervals for VRU-involved crashes so statistics on attribution of fault can be adjusted for future research or in policy settings.
Outputs
The primary outputs of this project will be a Final Research Report, at least one paper submitted to peer-reviewed journals, and at least one conference abstract/presentation. These outputs will summarize key findings from the modeling and will recommend minimum correction factors for analyzing VRU crash data with respect to adjusting for attribution of fault. Because of the direct policy relevance of this topic, we will also produce a policy brief to communicate key findings to elected officials, law enforcement, and transportation staff at various governmental levels. The policy brief will describe the study findings, offer some policy considerations, and be accompanied by public-facing infographics.
Outcomes/Impacts
Findings related to the attribution of fault in fatal and serious injury crashes between drivers and vulnerable road users (VRUs) are likely to have profound implications on both public opinion about the optimal solutions to address the road safety problems in the US, and on the laws, policies and funding decisions that transportation professionals and policymakers are likely to pursue. A better understanding of the presence and magnitude of errors in attribution of fault in statistics on crashes involving VRUs is critical to advancing Safe System goals and can help shift responsibility for road safety away from individual road user behavior and onto policymakers and road designers and operators to make systemic changes. Findings might also be useful to law enforcement officials in refining their post-crash investigative strategies.
Dates
12/1/2025 to 11/30/2026
Universities
University of California Berkeley
Principal Investigator
Corinne Riddell
c.riddell@berkeley.edu
https://orcid.org/0000-0001-9517-0739
Julia Griswold
juliagris@berkeley.edu
https://orcid.org/0000-0002-1125-3316
Project Partners
None
Research Project Funding
$82,015
Contract Number
69A3552348336
Project Number
25UCB03
Research Priority
Promoting Safety