How 20mph limits benefit the police

Communities consistently ask for slower residential speeds. There are many law and order benefits from police agreement to ‘light touch’ enforcement including responding to community wishes.

20 mph limits reduce the number and severity of road crashes. Drivers have more time to avoid a potential hazard and the impact energy at 20mph is less than half that at 30mph. Every 1mph slower reduces crashes and casualties in built-up areas by 6%[1]. In Portsmouth after two years of widespread 20mph limits a 22% reduction in casualties has been found. 20mph speed limits would thus:

  • Reduce the crash investigation workload for Traffic Police. Officers will have fewer witness statements to take, wreckage to clear, traffic to divert or get moving again, crash reports to write and legal and court hearings to attend. Plus less requirement for liaison with other emergency services.
  • Reduce the harrowing duty of informing relatives of the death or serious injury of loved ones.  This  task can result in the officers themselves needing counselling to deal with post traumatic stress.
  • Free up time for ‘light touch’ policing of the 20mph limits themselves. Police time that was previously spent dealing with injuries or liaising with other emergency services can be diverted to alternative law and order activities. These ‘opportunity cost’ savings are potentially significant and could be used for ‘light touch’ policing of 20mph limits such as ‘spot’ speed checks.
  • Reduce street crime. 20mph limits set the conditions for more walking, cycling and public transport use. As car use lowers, the number of observing “eyes” on the street rises. Busier, overlooked places feel safer and have more potential witnesses. As a consequence, some unlawful behaviours e.g. theft, are discouraged as the likelihood of community disapproval and/or being caught increases. In the longer term, reducing car use may also lead to reduced car crime and issues like parking obstruction. The number and mileage of roads that forces are expected to patrol is unchanged.
  • Reduce anti-social behaviour. 20mph limits let parents allow young people travel more independently. Youngsters are more confident to go further for appropriate activities such as youth clubs, sports or friend’s homes. Anti-social behaviour could be expected to fall.[D1] 
  • Improve working conditions. Traffic and other officers like PCSOs spend time walking, cycling or driving. Slower speeds have the advantage of making their working environment safer, quieter and less polluted. Fewer days will be lost in sick leave from injury or stress. Better working conditions reduces staff turnover and could potentially realise human resource savings through less re-training or recruitment.

Forces across England already support wide area 20mph limits without humps. Portsmouth has a dedicated officer.  Merseyside Police Chief Inspector John Hogan, said: “The police welcome any reduction in speed which may drive down the number of people killed or seriously injured on our roads. These 20mph limits will assist us to make the roads of Merseyside a safer place and to deal positively with a small number of offenders who continue to drive with a complete disregard for others.” To a great extent, 20mph limits are enforced by the majority of compliant drivers. Official endorsement of 20mph leads to a community consensus on driving at a speed that respects vulnerable road users.

20mph limits are increasingly being implemented by responsible traffic authorities in the UK and our police forces have an important role to play in making our streets better places to be.



[1] Taylor, Lynam and Baruya, 2000.


 [D1]Good to include a reference to evidence if possible

Open PDF

Be the first to comment

Please check your e-mail for a link to activate your account.