The most recent national study (Atkins, Nov, 2018) commissioned by the Department of Transport confirms public support and acceptance of 20mph limits, but says “The comparator analysis indicates that there is insufficient evidence to conclude that there has been a significant change in collisions and casualties following the introduction of 20mph limits in residential areas, in the short-term”.
This study only looked at 12 case studies, which did not include monitoring data from the Bristol 20mph scheme.
DfT – 20mph Research Study – Headline and Technical Reports
While the annual British Social Attitude Surveys: Public attitudes towards transport have consistently reported that the majority of the population support 20mph speed limits at a level of between 69-73%; in Bristol YouGov Tracker surveys in 2013, 2015 & 2017 showed a clear majority of public support for 20mph speed limits with the latest data revealing 62% on residential roads, 72% on busy streets.
Read more on 20mph: a survey of GB attitudes and behaviours