Support and compliance with 20 mph speed limits in Great Britain

  • Published: Bristol Business School, UWE, 2015
  • Authors: Tapp, A., Nancarrow, C., Davis, A.
  • Date Added: 05 May 2017
  • Last Update: 05 May 2017
  • Format: html


The prevalence of 20 mph speed limits across Great Britain (and 30 kph limits across much of Europe) is increasing. In Great Britain, by 2014 approximately 20% of the country’s residential streets already had signed 20 mph limits, and many more schemes are planned. However, while public support for speed limits generally is typically very high, lack of compliance with the limits by drivers is often a cause for concern. In general, there are a number of challenges to the support of, and compliance with, speed limits. These include awareness and appreciation of the benefits of low speeds; the contested risks posed by speeding; the tendency of drivers to over-estimate their own driving skill compared to other drivers; and the tendency for driving to become an automatic, habitual practice with low attention levels placed upon it, with the consequent ‘accidental’ breaking of speed limits. The paper explores the incidence of these effects and their implications in detail.


The survey was administered by YouGov, a reputable and well established polling and research company that is regularly used by government, charity and university sectors. The sample of 3074 respondents were randomly chosen from a large online panel, with the sample profiled to fit the Census derived demographics of the GB population. A probability (stratified random) technique of sampling was used to permit statistical inference. The sample further yielded 2297 respondents who responded as drivers of some form of motor vehicle. The effective sample size, i.e. the sample size that is permissible for statistical tests after weighting procedures was 2219.

Key Findings:

  • Lack of compliance with 20 mph limits in GB and 30 kph limits across Europe by drivers is a cause for concern. Data was collected to examine support–opposition and compliance–non-compliance amongst the GB population.

  • Four categories of driver according to support/opposition and compliance/non-compliance were examined in detail.

  • Results indicated that self-enhancement bias, social contagion and habitual/inattentive driving were important factors in explaining non-compliance.

  • Pro-active behaviour change strategies are required to create higher compliance levels.


20 mph limits, Driver compliance, Reasons, Behaviour changes.