The introduction of 20mph speed limits across Bristol has resulted in a 2.7mph fall in average traffic speeds – a ‘larger reduction than seen in previous evaluations in other cities’.
That is the conclusion of academics from the University of the West of England (UWE Bristol) who have evaluated the impact of the scheme on behalf of Bristol City Council.
The roll-out of 20mph limits across Bristol took part in six phases between January 2014 and September 2015. Along with reducing traffic casualties, the scheme was introduced to improve health and wellbeing across the city.
The researchers used a variety of data sources to examine changes in vehicle speeds, road traffic casualties, levels of walking and cycling, public perceptions and attitudes, and reported levels of health and wellbeing.
The study also employed a ‘more sophisticated analysis than previous studies of 20mph limits’ – including using individual speed data from more than 36 million vehicle observations, and controlling for other factors that might affect changes in traffic speeds.
Alongside the ‘statistically significant’ reduction in average traffic speeds, the study found that the scheme led to a reduction in the number of fatal, serious and slight injuries from road traffic collisions – equating to an estimated financial saving of more than £15m per year.
According to the report, an average of 4.53 fatalities were avoided each year, along with 11.3 serious injuries and 159.3 slight injuries.
Looking at the wider public health effects, the report found that the number of people who walk or cycle to work in Bristol has increased between 2010 and 2015 – with more people walking or cycling for 10 minutes or more in their local area on most days.
The percentage of people who walk to work has increased from 17.5% to 18.9%; while the number commuting by car fell from 53% to 44%. Rates of cycling to work also increased, up from 11% to 15%.
More children also now walk (59%) or cycle (31%) to school following the introduction of the 20mph speed limits.
In terms of public support, the report found that the ‘clear majority’ are in favour of the 20mph limits, with 62% supporting their use on residential roads and 72% on busy streets.
However, the report found scepticism among local residents about the lack of enforcement and a lack of compliance from ‘other drivers’. The researchers also identified an ‘increased readiness to report that it is sometimes okay to drive above the posted speed limit on residential roads’ among local residents who were interviewed for the study.
The academics conclude that the introduction of 20mph speed limits in Bristol ‘offers a model for other towns and cities across the UK, who are seeking to reduce traffic speeds, cut road traffic casualties, and promote community health and well-being through road danger reduction’.
They also suggest that in order to assess the effectiveness of 20mph speed limits, it is ‘vital that other towns and cities follow Bristol’s example, and prioritise the ongoing collection and analysis of appropriate data on vehicle speeds, road traffic casualties and wider public health impacts’.
Welcoming the report, Rod King MBE, founder of 20’s Plenty for Us, said: “Default 20mph limits are an important foundation for making our places better places to be. They are affordable, reduce speeds, reduce casualties and make our places more friendly for walking and cycling.
“This study shows that the public health benefits are significant. It is now time to standardise on a 20mph default at national level to increase benefits, reduce implementation costs and maximise the excellent return on public funds.”