Can a 20mph speed limit in Marlborough improve road safety & air quality?Sirs,
Transition Marlborough suggested the introduction of a 20mph speed limit in Marlborough to reduce toxic emissions - in our 'Air Quality Action Plan'. We were, therefore, very supportive of our town councillors when they asked Wiltshire Council to install the speed recorders (metrocounts) on all the roads leading into Marlborough, last September.
As a result of this short exercise there is now a possibility of introducing 20mph speed limits along some of the busy streets that are in the Air Quality Management Area. This could not only prevent road accidents but also cut the NO2 and ultra-fine particulate emissions associated with stopping and starting. Traffic congestion could also be reduced if more people are encouraged to walk or cycle, once the streets become safer. Obviously any speed changes will depend on the support of local residents and Councillors.
20mph speed limits have already been introduced in many of the surrounding villages, as well as in larger towns and cities in the UK. The University of the West of England has recently analysed the impact of 20mph roll-outs, between 2012 and 2015, in Bristol. Their study employed a more sophisticated analysis than previous studies of 20mph limits, including using individual speed data from over 36 million vehicle observations and controlling for other factors that might affect changes in traffic speeds.
The results indicated that 4.53 fatalities, 11.3 serious injuries and 159.3 slight injuries have been avoided per year. This means that two child lives will be saved every three years; 3 older adult lives will be saved every two years; and 3 pedestrian deaths will be avoided every year. More children in Bristol now walk or cycle to school.
The latest figures from Edinburgh's 20mph zones, reveal 24 percent less casualties between October and December last year - dropping from 1,067 to 809 compared to the same period the previous year. Nearly a third less people are also being killed or seriously injured.
An Edinburgh City Councillor said, “The fact that anyone hit at 20mph is seven times more likely to survive than someone struck at 30mph is something we can’t ignore. What’s more, by calming traffic on shopping and residential streets, we’re encouraging more people to walk and cycle, improving health and enhancing our environment."
Last June the National Institute for Health and Care Excellence (NICE) recommended speed limits of 20mph to improve air quality. NICE guidance advises authorities to set “20 mph limits without physical measures to reduce speeds in urban areas where average speeds are already low (below around 24 mph) to avoid unnecessary accelerations and decelerations”. NICE further advises that physical speed reduction measures, already in use for road safety purposes, can be used to encourage a reduced steady speed for longer stretches of road, and thus avoid emissions from acceleration and deceleration for road humps.
Let's hope that our Town and Wiltshire Councillors keep up the good work and put our health and road safety first!
Dr Sam L J Page