Speed zones...
A swathe of new applications are being considered to bring in 20mph limits in our towns and surburban roads. looks at the pros and cons
of 170 a year.
As well as the obvious gain in the avoidance of human suffering, the university estimated the economic gain to the city was more than £15m a year.
Similar schemes in Edinburgh and Portsmouth were also found to reduce casualties by up to 15%, but Manchester abandoned its 20mph zones after they found speeds and accidents had fallen only marginally.
Kent County Council has plans to introduce four new 20mph zones across Kent - two town-wide schemes in Tonbridge and Faversham, and two centre-wide schemes in Tunbridge Wells and Margate.
But the justification is not specifically casualty reduction, but rather KCC is using a Government “active travel grant.” The argument is that if the public perceive the town centres to be safer, they are more likely to adopt “active travel” modes - ie, walking or cycling, and so help improve the nation’s health and tackle obesity.
The Tonbridge scheme will extend north from the A21 between Upper Haysbrook Road in the west and the A26 in the east.
Initially, there will be only road markings, signage and gateways to denote the 20mph zone, but KCC warns that “We will be monitoring the effectiveness and there may be a need for further measures to ensure that the road design encourages motorists to keep to the 20mph limit.”
The Faversham scheme will extend to the north of London Road, between Link Road and Love Lane.
In both Tunbridge Wells and Margate there are already a number of existing 20mph roads in the zone. These will be added to.
Tunbridge Wells will now include Camden Road, Calverley Road, High Street, Monson Road, Mount Pleasant Road, Mount Ephraim Road and Vale Road, among others.
While Margate will include Bilton Square, Broad Street, Eaton Hill, Fort Hill, Fort Road and Grosvenor Place, among others.
All four schemes have been pushed through under an “experimental traffic order”, meaning they start on Friday, September 18 and run for 18 months, after which KCC will make a new order to keep them, alter them or just allow them to lapse
Although the evidence that more walking and cycling does improve public health is well documented, there are some who oppose 20mph zones on the grounds they increase pollution and so have a detrimental effect on health. This is based on the recognition that most road cars achieve their greatest fuel efficiency at around 55mph. Driving either faster or slower results in fewer miles per gallon.
However, whether this translates directly to more pollution is less clear. A study by Imperial College London found petrol cars produce more more nitrogen oxide pollution at 20 mph than at 30mph, while diesel cars produce less. While for PM10 particulates (very small particles of dust or smoke that can be absorbed by the lungs) both diesel and