20 mph limits give great value for money. Slower speeds can be funded from many sources and money combined from different funders can help make communities safer and improve the quality of life for all road users.
Public spending is increasingly monitored for value for money. Where speeds are an issue, for instance where people live, a first question is whether to aim to implement zones (with traffic calming) or signed only limits. Cost effectiveness analysis suggests that the benefits in casualties prevented of 20 mph zones for high casualty areas are greater than the implementation costs, whereas those in low casualty areas are not. 20 mph zones become cost effective when a road has over 0.7 casualties per km per year. Zones cost approximately £60,000 per km at 2005 prices.
However, 20mph limits (without traffic calming) are 7.2 times more cost effective per mile per hour reduced than zones. Evidence from early implementations of town-wide 20mph limits have shown a 20%+ reduction in casualties.
Implementing a 20 mph limit scheme involves a public education campaign and consultation, signage, some signposts, and changing traffic regulation orders with advertising these in local media. ‘Light touch’ policing can enforce it.
Portsmouth’s Total 20 mph implementation cost was £425,000 for 1200 roads (94% of its network). Per street this is £333 or £1,158 per km. £425,000 is equivalent to two signal controlled junctions. In the DfT review of Portsmouth’s 2nd year of this policy a 22% drop in collisions was found compared to previous 3 year’s average. Oxford spent £300,000. The “value” of this reduction in casualties has enabled local authorities to show that implementing area-wide 20mph limit can provide a First Year Rate of Return of over 800%.
Funding Options for 20mph Limits
1) Local Highways/Transport planning department from central government funds, for instance as part of the Local Transport Plan budget, or ongoing capital works programme. This is the most common route. It was how limits were paid for in Portsmouth, Oxford, Islington, Bristol and many more.
2) Transport Authorities like Transport for London.
3) Local Sustainable Transport Fund. A local authority can bid to the Department for Transport’s LSTF, which specifically includes 20 mph speeds. There are £5 million and £50 million pots. As an example, 20’s Plenty for Us believe that West Sussex CC have put 20 mph limits in their 2011 bid for Chichester.
4) Councillor vote in deciding amendments when setting council budgets. For instance, in York a Green Party budget amendment in 2009 succeeded in getting £30,000 to set up a pilot 20 mph limit scheme.
5) Developer money as part of a Section 106 agreement to benefit nearby residents, for instance when new homes or businesses are built.
6) Primary Care Trusts (PCTs) will see a health improvement if fewer people are being injured and more people become physically active due to slower speeds. Glasgow’s Health Commission recommended 20 mph zones. Councillors agreed £100,000 for 280 streets in 20 areas, 2 each in the 10 area health committees in Dec 2010.
Liverpool’s PCT agreed 40% of funding for limits in Liverpool in November 2011 amounting to - £665k of £1.665m
7) Local ward or assembly funding. City of York Council has agreed this in principle, though ward funding budgets could only part fund a ‘Total 20’. This has also been done in Sheffield where the City Council has made money available to those communities who want it.
Most importantly we have found that where councillors do support 20mph speed limits for residential roads then usually there are ways to find the money required for implementation.
 Grundy, Steinbach, Edwards, Green, Armstrong & Wilson – Effect of 20 mph traffic speed zones on road injuries in London www.20splentyforus.org.uk/UsefulReports/20-mph-zones-and-road-safety-in-london.pdf
 Department for Transport – Interim Evaluation of the Implementation of 20mph Speed Limits in Portsmouth.
 Warrington Borough Council – 20mph Speed Limit Pilots Evaluation Report – Para 13.10