Effects of city-wide 20 mph (30km/hour) speed limits on road injuries in Bristol, UK

Bornioli, Anna; Bray, Isabelle; Pilkington, Paul; Parkin, John

Abstract

Twenty miles per hour (32 km/hour) or 30 km/hour speed limits represent a potential strategy to reduce urban road injuries and are becoming increasingly widespread. However, no study has conducted a robust evaluation of the effects of city-wide 20 mph speed limits on road injuries. This study reports the effects of such an intervention, based on a natural experiment that took place in Bristol, UK. Based on a stepped-wedge design using count data, negative binomial regressions showed that between 2008 and 2016, the 20 mph speed limit intervention was associated with a city-level reduction of fatal injuries of around 63% (95% CI 2% to 86%), controlling for trends over time and areas. There was also a general trend of reduction of the total number of injuries at city level and in 20 mph roads. These findings highlight the potential benefits of city-wide 20 mph speed limits. We hypothesise that this city-wide approach may encourage a general behaviour change in drivers that, in turn, may contribute to reducing injuries across the city.

• Journal Article Type: Article
• Acceptance Date: Jun 26, 2019
• Online Publication Date: Jul 13, 2019
• Publication Date: Feb 1, 2020
• Deposit Date: Jun 26, 2019
• Publicly Available Date: Jun 28, 2019
• Journal: Injury Prevention
• Print ISSN: 1353-8047
• Electronic ISSN: 1475-5785
• Publisher: BMJ Publishing Group
• Peer Reviewed: Peer Reviewed
• Volume: 26
• Issue: 1
• Pages: 85-88
• DOI: https://doi.org/10.1136/injuryprev-2019-043305
• Keywords: speed, planning, public health, motor vehicle, longitudinal methodology
• Public URL: https://uwe-repository.worktribe.com/output/1492332
• Additional Information: This article has been accepted for publication in Injury Prevention, 2019 following peer review, and the Version of Record can be accessed online at: https://injuryprevention.bmj.com/content/early/2019/07/13/injuryprev-2019-043305.info
• Contract Date: Jun 28, 2019