Warwickshire Green Party Councillors recently put forward a motion to plan and cost a 20mph speed limit in all residential areas. This was watered down by the Conservatives, but a report on 20mph limits will still come to cabinet in early 2022.
Moving to 20mph limits in residential areas is a significant step and here’s some of the questions that often come up.
How many accidents will a 20mph limit prevent?
In Warwickshire there were 629 reported road casualties on 30mph roads in 2019 (1478 on all roads), including 9 deaths. Evidence from other local authorities show a 30-40% reduction in casualties. Even a 20% reduction would see on average over fewer 100 casualties and save 2 lives per year.
Will it work? What about enforcement?
Evidence shows a 4-5mph reduction on faster 30mph roads, 1-2 mph reduction where speeds are already lower. Every 1mph reduction reduces casualties by 6%. Compliance rises the more widespread the limit is and over time.
People peg their speed to the limit. So if the limit is 40mph they will travel at 45mph. If it is 30mph they will travel at 35mph. Still over the limit, but a lower speed.
Enforcement is therefore the same issue at 20mph as at 30mph – it does not require a different approach.
Compared to expensive and controversial speed humps / other traffic calming which we can only do in a small number of places this is very effective.
A 20mph limit is one of the easiest ways to increase active travel such as walking and cycling because people feel safer.
Where else has it been done?
Bath & North East Somerset, Chester, Calderdale, Bristol, Edinburgh, large parts of London.
Calderdale: cost £821k, £1600 per km of road. £3million saved in reduced casualties in first 3 years. Casualty by 30%
Cheshire West: cost over four years £800k, £3.5 million saved in casualty reductions in 3 years. Casualties fell by 43%
From April 2023 the whole of Wales is planned to have 20mph limits.
Why does it work?
Being hit by a car going at 30mph is the equivalent of falling out of a 3rd story window.
But being hit by a car which is only going at 20mph is like falling out of a 1st story window - it's much less likely to be fatal.
How much will it cost?
The cost for Warwickshire would be about £2.2m based on the experience of other local authorities adjusting for the fact that Warwickshire is a more rural county. This is under £4 per head. This includes the costs for Traffic Regulation Orders.
If you factor in the cost of police and NHS time and expertise and damage to property and vehicles the financial saving to Warwickshire of introducing a 20mph limit will be £8.7m per year. More police and NHS time for other local priorities.
How popular is it likely to be?
According to the Department for Transport Attitudes to traffic survey 71% of people support 20mph limit on streets near them, 14% are against, 15% don’t know.
Where can I find out more?
Most of this information is from https://www.20splenty.org/ . If you sign up to updates you’ll also get access to their seminar on 20th of every month. You can also follow them on social media.
If you’ve got any more specific comments about Warwickshire please get in touch!
