The research concludes that:
20mph limits are supported by the majority of residents and drivers
- there has been a small reduction in average (median) speed - less than 1mph
- vehicles travelling at higher speeds before the introduction of the 20mph limit have reduced their speed more than those already travelling at lower speeds
There is not enough evidence to conclude that that there has been a significant change in collisions and casualties following the introduction of 20mph limits in residential areas.
Atkins, Aecom and Professor Mike Maher (UCL) were commissioned by the Department for Transport in 2014 to address a gap in the evidence available on the effectiveness of 20mph speed limit (signed only) schemes. Twelve case study schemes were studied, from a variety of area types, road types and scale.