Active Travel

Reasons and objections for implementing 20mph speed limit

Take a look at the Briefing to Members

Benefits of introducing a 20mph default limit

How does it work and how much does it cost?

Global Road Safety Experts and Ministers from 130 countries (Including the UK) adopted the “Stockholm Declaration” at a road safety conference on 20th February 2020. It requires 20mph limits where vulnerable road users and vehicles mix.

A comprehensive report on the effect of 20mph speed limits was made by Professor Mike Maher and Atkins published in November 2018. The study shows that 75% of residents support an existing 20mph limit.

RoSPA research has shown that a 1 mph reduction in speed results in a 5% reduction in accidents.

Reasons for 20 mph limits:

  • Supported by the majority of residents.
  • A slower speed encourages more people to walk and cycle.
  • Improve social cohesion in our town because more people stop and talk to others.
  • Reduced noise pollution which is seen as one of the most significant health benefits.
  • Drivers feel more relaxed which reduces cardiovascular stress and diabetes.
  • We kill or injure fewer people, especially children who are poor at judging vehicle speed. Injuries are less serious because of slower speeds.

A 20 mph default speed limit is a necessary foundation for so many other initiatives including low traffic neighbourhoods (LTNs).


20 mph is not enforceable.

I have spoken to Chief Inspector Rob Dickinson head of Cheshire road crimes policing. He refutes this and said they would enforce a 20mph limit if there was some evidence of danger being reported. Enforcement though is not a key issue; we know from studies that just by reducing the legal speed limit, drivers, on average, drive slower which will result in fewer and less serious collisions. In 2022 all new cars must be fitted with speed limiters that will detect the local speed limit and prevent the car from exceeding it.

There is no reduction in pollution.

There is little evidence on the effects on air pollution and there is no evidence that air pollution increases. An extensive study has shown that the reduction in noise pollution gives significant health benefits.

20 mph does not reduce collisions.

Specific local authorities have reported 23% reduced casualties in Bath, 27% in Warrington and 30% in Calderdale. The link between speed and casualties is clear which is why WHO (World Health Organisation), EU (European Union), ETSC (European Transport Safety Council) and iRap (International Road Assessment Programme) support this limit in urban areas where people mix with motor traffic.

It will cost too much.

The cost is around £800K for most boroughs. This can be spread over a number of years. What value do you put on 1 person’s life?

The default speed limit of 30mph was introduced on 18th March 1935. Back then there were fewer than 2 million cars on the road, today there are over 33 million. There is no doubt that motor cars are essential for modern life, they provide freedom and convenience but they are not without a huge cost to our society. 30 mph default limit is no longer fit for purpose.

The diagram below is from the Parliamentary Advisory Council for Transport Safety  it shows that nearly 500 deaths of vulnerable road users in 2019 were due to a collision with a car.

Earlier this year (2020) a task force for the Welsh Government recommended a universal default speed of 20 mph. The chairman Phil Jones said “there was overwhelming evidence that lower speeds result in fewer collisions and severity of injuries”. These plans have received initial backing by the Senedd.

A detailed study of a 30km/hr speed limit in Lausanne, Switzerland concluded:

  • Inner-city speed reduction reduces road traffic crashes and noise exposure.
  • Speed reduction prevents cardiovascular diseases and diabetes.
  • Speed reduction reduces the number of noise annoyed and sleep disturbed people.
  • Overall, health benefit from noise reduction is more relevant than safety benefits.

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