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Benefits of 20mph limit schemes

Safety benefits

National and international studies show that lowering the speed limit from 30mph to 20mph reduces the number of casualties. This is recognised by bodies such as the World Health Organisation and the UN General Assembly recently mandated 20mph as the right speed limit where people and motor vehicles mix.

The reduction from 30mph to 20mph is already being implemented across many towns in the country.

To exclude a road from a scheme, the highway authority must show that it has considered the needs of pedestrians and other vulnerable road users. Other schemes have found:

  • casualty figures fell by 23% specifically in Bath, along with other reductions in Edinburgh, Brighton and other towns
  • drivers have observed the 30mph limits more as well as the 20mph in Bristol
  • implementing 20mph speed limits leads to a general reduction in speeds. On faster roads, speeds are reduced more than 4mph in Bristol and 7mph in Portsmouth
  • a 1mph reduction in speeds on urban roads is recognised as leading to 6% fewer casualties
  • two out of three people surveyed supported the reduction before and after implementation.

20mph schemes and active travel

Studies have shown that 20mph schemes helps to encourage active travel by increasing walking and cycling levels.

Walking and cycling can make a very positive contribution to improving health and tackling obesity, improving accessibility and tackling congestion, and reducing carbon emissions and improving the local environment.

Traffic calming measures

Traffic calming measures are not always needed when reducing the speed limit. Where calming measures are needed, there are many alternatives that can be used:

  • bolted down bollards
  • lines
  • orcas and wands
  • posts
  • planters
  • parklets
  • signs
  • staggered parking bays.

Whilst speed bumps reduce the speed of motorised vehicles and are commonly used, studies have shown they are not often required. NICE recommends 20mph without speed bumps for; better air quality, less noise, vibration and road wear.

Economic costs

At £5 to £10 per head, depending on the specifics of the scheme it’s good value for money. Fewer casualties and more walking and cycling mean that many schemes pay back in less than a year.

Businesses are able to thrive, as access is safer for pedestrians and cyclists. This means more money is available to the local economy.

There is also no significant increase in the time it takes to cross these zones. Many bus companies have found no difference in their journey times.

As with all speed limits the police can enforce 20mph. Speed assistance technology in new cars by 2022 will automatically increase the compliance. Any drivers that break the speed limits will receive warning letters, or will attend a speed awareness course.

Further reading and references

For more information about our research into the benefits of these schemes please visit these websites:

Healther, safer, cleaner. Faversham 20.