Conclusion: Indications for effectiveness
- Speed limit reductions may be effective on their own in reducing accidents but additional measures may be needed. Speed limit zones in built up areas reduce personal injuries.
- Area-wide traffic calming appears to be a promising intervention for reducing traffic injuries and deaths in towns and cities .Area wide traffic calming schemes on the average reduce the number of injury accidents by about 15%. the largest reduction is found for residential streets (about 25%), a somewhat smaller reduction is found for main roads (about 10%). Similar reductions are found in the number of property damage only accidents.
- There is moderate evidence that 20 mph zones are effective measures for reducing road injuries and deaths, and reducing road casualties in child pedestrians.
- There is moderate evidence that 20 mph zones are effective measures for reducing road injuries and deaths, and reducing road casualties in child cyclists.
- There is moderate evidence that implementation of traffic-calming measures may reduce child road casualties, accidents, injuries and deaths.
Recommendations (for research & practice)
There is a clear need for more controlled studies to measure effect. These studies also need to have longer follow-up periods and/or larger samples of sites if there is to be sufficient statistical power to assess differential effectiveness (either in subgroups of people – e.g. children – or subgroups of treatment types or locations – e.g. deprived areas).
Given the wide variation in results for many of the interventions in the effectiveness studies reviewed (either between studies or between sites within studies), the presumption that randomised controlled trials cannot be conducted for local road-design changes and traffic calming seems unwarranted. We can see no ethical or practical reasons why the possibility of conducting randomised controlled trials in this research field should not be re-visited.
Changes to the physical environment can have unintended consequences that may disadvantage some groups. For example, changes that remove physical features (such as the distinction between pavement and road) might increase uncertainty on the part of motorists, and so promote a safer driving style. However, they might also make negotiating a street more difficult for people with a visual impairment.
More guidance on research into practice on interventions related to road design is available at www.nice.org.uk/guidance/PH31
Review Date: 02/07/2012
Articles (reviews) and reports were included that were published between 1990 and 2011, in English and Dutch. The outcomes of the study were reviewed by the Dutch Consumer Safety Institute.
Strategy: An online literature search was performed by a researcher of the Consumer Safety Institute and after this a more thorough search was performed by the documentation centre of CSI (Catalog CenV, Pubmed, Injury lit, Google, Websites, 'Grey' literature). Results of each search were compared on differences and potential missed studies were added. First the titles and then abstracts were scanned in order to include relevant studies. In the case of insufficient information obtained from abstracts the full text articles were obtained. Relevant articles were scrutinized and background documents were created. In addition, relevant references of included articles were checked on new and relevant articles (i.e., snowball search).
The outcomes of the study were reviewed by an expert in the field of child safety in the summer of 2012.
Area-wide traffic calming for preventing traffic related injuries (version 1.0)
F. Bunn, T. Collier, C. Frost ... [et al.] (2003)
Effect of 20 mph traffic speed zones on road injuries in London, 1986-2006: controlled interrupted time series analysis. (version 1.0)
C. Grundy, R. Steinbach, P. Edwards ... [et al.] (2009)
Interventions to prevent unintentional injury in children on the road : report 1 : Systematic review of effectiveness and cost-effectiveness of road and street design-based interventions aimed at reducing unintenional injuries in children (version 1.1)
Kate Ashton, Tiffany Moxham, Julie Frier ... [et al.] (2009)
What are the most effective ways of improving population health through transport interventions? Evidence from systematic reviews (version 1.0)
D.S. Morrison, M. Petticrew, H. Thompson (2003)
Area-wide urban traffic calming schemes: a meta-analysis of safety effects (version 1.1)
Rune Elvik (2001)