20mph speed limits


Cornwall is one of the first rural areas to reduce speed limits from 30mph to 20mph on residential roads and in built-up areas. It will make roads, safer, healthier and greener for everyone.

After a successful trial (Phase 1) in Camelford, Falmouth and Penryn areas during 2022, the scheme has been approved to be rolled out across the whole of Cornwall.

Cornwall Council aims to reduce both death and serious injury by 50% on our roads by 2030, and 20mph limits will support this.

The benefits of reducing speeds to 20mph

Research provides a strong link between traffic speed and the severity of injury when a collision occurs. If someone is struck at 20mph they have a 90% chance of survival compared to a 50% chance if struck at 30mph.

Travelling at 20mph provides many other benefits too:

  • Making our streets safer. This will reduce casualties and community inequality.
  • Increasing child and adult activity levels. This will improve health and wellbeing.
  • Providing a safe environment. This will encourage more people to walk and cycle.
  • Supporting climate change declaration. This will include lower emissions and tackling congestion. As well as supporting our ambition to be Carbon Neutral by 2030.
  • Creating a stronger sense of community as more people come together to use the space.

Walking and cycling

Villages, towns and cities should be places where people are free to travel in ways that are:

  • Safe
  • Sustainable
  • Healthy
  • Fair

Faster speed limits make using roads dangerous where people live, work and play. This particularly affects vulnerable road users, including children and the elderly.

Lower speeds mean people feel more comfortable to walk and cycle and it is safer for children to walk to school. Older people also feel more able to travel safely.

Air Quality

There is little evidence to suggest that reducing vehicle speeds to 20mph increases pollution. It is not as straightforward as more time driving equals more pollution. Driving styles, acceleration and braking are all contributory factors to increased emissions. Other research has shown that up to 75% of road transport particulate emissions come from tyre and brake wear. Slower speeds encourage a smoother driving style, which ultimately decrease's emissions.

Research has found that reducing speeds from 30mph to 20mph reduced CO₂ emissions up to 37.8% and NOx emissions by 51.0%. This is while only having a minimum impact on journey times. The impact of different driving styles, vehicle size, and fuel type were also investigated and found to impact the results.

Journey times

Journey times on roads in urban areas tend to be determined by junctions, crossings and parked vehicles, rather than the speed limit. Often lowering the speed limit to 20mph will have little or no impact on journey times. Where there is an impact, this would be negligible, but in turn would make the roads safer for pedestrians and cyclists.

Bus journey times were reviewed as part of Phase 1 and were found to be negligible.

Less acceleration and braking smooths traffic flow, reduces gaps between cars and reduces idling.

Noise pollution

Noise research studies show about a 3 decibel (dB(A)) reduction when reducing a 30mph speed limit to 20mph. This is perceived as halving ambient noise.

Fuel

Fuel consumption is mainly influenced by the way we drive. Driving at a consistent speed is better than stopping and starting. Accelerating up to 30mph can take over twice as much energy as accelerating up to 20mph. A default 20 mph speed limit and a smooth driving style, can help avoid unnecessary speeding up and slowing down, saving fuel.

A study by the Transport Research Board identified that 30km/h zones (18.6mph) have a 12% reduction in fuel consumption. 

Where 20mph won’t be introduced

We are reviewing all roads where the existing limit is 30mph, with the intention to reduce to 20mph. Urban areas with high pedestrian and cyclist movements will be higher priority. This could include areas around schools, shops, markets, playgrounds.

For some roads, it may be appropriate to keep 30mph or deliver a more focused 20mph section. This will be a considered decision, based on local circumstances. Exceptions will generally be major roads and where vehicles are the primary function.

An exceptions process has been developed to help support this process. This will be applied consistently to any 20mph scheme, regardless of how it is funded.

Speed limits higher than 30mph

Speed limits higher than 30mph will not qualify for 20mph. We appreciate that communities with speed limits of 40mph or above, may face difficulties. There may be opportunities to improve the local environment through other initiatives. Such Initiatives could be nominated through the Community Area Partnership Highway Scheme.

Police enforcement

Devon and Cornwall Police can and will enforce 20mph speed limits. This will be targeted based on evidence. We must not rely on legal enforcement as the only means to drive compliance. Road safety is something all road users have responsibility for. Road user respect and driver behaviour is crucial.

Cornwall Council will work with the Police during Phase 1 and beyond. Enforcement will be deployed for consistent high levels of non-compliance and risk to health (injury).

Whether you live in a 20mph or travel through 20mph, we ask you to respect those limits in place.

Timelines for the rollout of 20mph

Statutory public consultation will be undertaken for each phase of delivery.

Using data on serious road collisions and data from Phase 1 we have identified the priority order for the rollout of the changes.

2023/24

  • Camborne, Pool, Illogan and Redruth
  • West Penwith
  • Truro and the Roseland

2024/25

  • Hayle and St Ives
  • St Austell and Mevagissey
  • Newquay and St Columb
  • Cornwall Gateway
  • Liskeard and Looe
  • China Clay

2025/26

  • Helston and South Kerrier
  • Bude
  • Launceston

2026/27

  • Wadebridge and Padstow
  • Bodmin
  • Caradon
  • St Blazey, Fowey and Lostwithiel
  • St Agnes and Perranporth

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