The cost-effectiveness of mandatory 20 mph zones for the prevention of injuries

J Public Health (Oxf). 2013 Mar;35(1):40-8. doi: 10.1093/pubmed/fds067. Epub 2012 Aug 21.


Background: Traffic calming and speed limits are major public health strategies for further reducing road injuries, especially for vulnerable pedestrians such as children and the elderly. We conducted a cost-benefit analysis (CBA-favoured by transport economists) alongside a cost-utility analysis (CUA-favoured by health economists) of mandatory 20 mph zones, providing a unique opportunity to compare assumptions and results.

Methods: A CUA from the public sector perspective and a CBA from a broader societal perspective. One-way, threshold and probabilistic sensitivity analyses were undertaken.

Results: In low casualty areas the intervention was not cost-effective regardless of approach (CUA: cost per QALY = £429 800; CBA: net present value = -£25 500). In high casualty areas, the intervention was cost-effective from the CBA (a saving of £90 600), but not from the CUA [cost per quality-adjusted life year (QALY) = £86 500; assuming National Institute for Health and Clinical Excellence's benchmark for approving health technologies].

Conclusions: Mandatory 20 mph zones may be cost-effective in high casualty areas when a CBA from a societal perspective is considered. Although CBA may appear, in principle, more appropriate, the quality, age or absence of reliable data for many parameters means that there is a great deal of uncertainty and the results should be interpreted with caution.

Publication types

  • Comparative Study

MeSH terms

  • Accidents, Traffic / prevention & control*
  • Cost-Benefit Analysis / economics
  • England
  • Health Promotion / economics*
  • Health Promotion / methods*
  • Humans
  • Quality-Adjusted Life Years
  • Sensitivity and Specificity
  • Wounds and Injuries / prevention & control*