Support and compliance with 20mph speed limits in Great Britain

  • Published: Transportation Research Part F: Traffic Psychology and Behaviour. Vol. 31 pp 36-53. 2015.
  • Authors: Tapp, A., Nancarrow, C., and Davis A.
  • Date Added: 07 Apr 2016
  • Last Update: 07 Apr 2016
  • Format: html


To determine:

  • Levels of support and opposition to 20mph speed limits by drivers.

  • The reasons for support or opposition.

  • The extent to which drivers claim they may or may not comply with 20mph limits.

  • The nature of the interactions between support/opposition and compliance/non-compliance.

  • The effect of other motorists on a driver’s speed.

  • Attitudes to driving and speed limits, and how these might affect behaviour.


Survey (administered by YouGov)

Key Findings:

The following behaviours were identified as potentially negatively impacting compliance with 20mph limits:

  • Contested link between speed and accidents: the lack of awareness of or disagreement with the link between speed and accidents

  • Speed limit attitude–behaviour incongruence: the approval of speed limits but lack of personal adherence to limits

  • Personalising speed limits: the tendency to drive above the speed limit but to regard this behaviour as law abiding

  • Self enhancement bias: the tendency to regard one’s own driving skills as superior to others; or to regard one’s own speeding as less than or safer than others

  • Social contagion effect: the tendency to drive at the perceived average speed of other traffic

  • False consensus effect: the general belief that other drivers travel at higher speeds than the reality

  • Automaticity: inattentive and / or habitual driving that results in the lack of awareness of one’s own speed

  • JIMBY effect: ‘Just in my back yard’ – the tendency to drive slowly in one’s own neighbourhood but more quickly elsewhere.


20mph zones, social marketing, compliance


Research paper. The key findings have been paraphrased from the original source for simplicity.