Accelerating Roundabout Implementation in the United States - Volume IV of VII: Review of Fatal and Severe Injury Crashes at Roundabouts

Steyn, Hermanus; Griffin, Ashleigh; Rodegerdts, Lee A. · 2015 · ROSA P / United States. Department of Transportation. Federal Highway Administration. Office of Safety

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Summary

This report, Volume IV of a seven-part series by the Federal Highway Administration (FHWA), investigates fatal and severe injury crashes at roundabouts in the United States to identify design modifications that could further enhance safety. While roundabouts are proven to reduce severe crashes by an average of 80 percent, the growing prevalence of these intersections necessitated a deeper analysis of the specific characteristics contributing to the rare but serious incidents that do occur. The study aims to determine whether elements of roundabout design practice can be modified to reduce the likelihood of fatalities and severe injuries. The research team conducted a comprehensive review of all known fatal crashes at U.S. roundabouts from 2005 to 2013, identifying 46 such incidents across 19 states. Due to the low frequency of fatalities, the study supplemented this data with an analysis of injury crash records from Washington and Wisconsin, two states with high roundabout implementation rates. The team utilized the Fatality Analysis Reporting System (FARS) and state Strategic Highway Safety Plans to establish national and state benchmarks for comparison. The analysis focused on crash characteristics, including vehicle type, driver impairment, speed, light conditions, and involvement with fixed objects. The findings reveal that fatal crashes at roundabouts differ significantly from general intersection crashes. Eighty-three percent of fatal roundabout crashes were single-vehicle incidents, compared to 67 percent for all intersections. Key overrepresented factors in roundabout fatalities included motorcycle involvement (46 percent vs. 23 percent nationally), fixed object strikes (85 percent vs. 11 percent), impaired driving (52 percent vs. 21 percent), and speeding (57 percent vs. 20 percent). Notably, 83 percent of fatal crashes occurred during dark light conditions. In the injury crash analysis from Washington and Wisconsin, similar trends emerged, with significant proportions of crashes involving motorcycles, impaired drivers, and vehicles striking curbs or other fixed objects. The report concludes that specific design and operational strategies can mitigate these risks. Recommendations include modifying curb designs, particularly at the interior edge of truck aprons and splitter islands, to reduce the severity of impacts. The authors emphasize the need for increased visibility and conspicuity of intersections, as well as better placement and protection of fixed objects like sign posts and light poles. Additionally, the high prevalence of impaired driving in these crashes underscores the importance of continued driver education and enforcement efforts. These findings provide practitioners with evidence-based guidance to refine roundabout designs and further minimize the occurrence of fatal and severe injury crashes.

Key finding

Fatal crashes at roundabouts are overrepresented for motorcycles, fixed objects, and impaired driving, with 83 percent being single-vehicle incidents.

Methodology

dataset

Sample size: 46

Provenance

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Summary generated by qwen3.6-27b-prismaquant on 2026-06-10; verification: verified.

Topics

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• intersection design
• incidence prevalence
• comparative international
• fatality injury trends
• vru crash typology
• demographic disparities

Information type

What kind of knowledge this paper contributes, grouped by family — independent of topic (what it is about) and method (how it was studied).

• Empirical Findings: crash risk outcomes