20 mph speed limits – public health perspective tom may public health practitioner & physical...
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20 mph Speed Limits – Public Health Perspective
Tom MayPublic Health Practitioner & Physical Activity LeadHertfordshire County Council
Overview
• Report Summary from Director of Public Health (Item 2d in papers)
• Implementation Evidence from Public Health in Bristol
• Summary of HCC Public Health Directorate Position
DPH Interpretation of the Evidence
• In some areas with high rates of road casualties the evidence is tending to suggest speed limits at 20mph are an intervention which can be effective
• It won't work in all areas so needs careful consideration of where it will work and where it won't
Public Health Interpretation of the Evidence
• "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."
- Journal of Public Health in 2013
20 mph
30 mph
The risk of fatal injury to adult pedestrians and vehicle impact speed
Source: RoSPA – Nov 2012
Candidate locations
• There are several areas in Hertfordshire where the road casualties give some cause for concern, but we would need to determine whether these areas were areas in which a 20mph zone would work
Some Findings From Bristol
• The results showed a small but significant reduction in average daytime speeds in both areas; a 1.4mph reduction in inner south and 0.9mph reduction in inner south. Other headline findings include:
• 65% of roads saw a reduction in mean speeds;• There was no measurable change in air quality or noise;• Pedestrian causalities remained constant in both areas;• Community support for lower speed limits increased from
70% to 89% after implementation.• There was mean of a 23% increase in walking and a
20.5% increase in cycling in the pilot areas
Inactivity In Strategic Context
• £166 M* in Hertfordshire (12-22% burden of this falls on the NHS) per year
• HWB Strategy – 9 Priorities - Increasing Physical Activity
- Healthy Weight- Mental Health
* includes benefit payments, sickness benefits, loss of production and loss of taxation revenue due to loss of earning/unemployment
20mph Public Health Position Summary
• Evidence is not always clear cut but on balance public health support for implementation where appropriate
• Safety evidence – stronger (where slower speeds are achieved)
• Cardiovascular health evidence – not as strong but promising
• A public health approach would suggest considering the intervention in areas it would have greatest impact.
• Supportive environments can help encourage physical activity
