On its 40th anniversary, do speed bumps still serve their purpose?

The speed bump turns 40 this year, so we ask the question: are traffic-slowing measures still fit for purpose?

The speed bump originally originated in early 1900s America but didn’t arrive on British roads as a traffic calming measure until 1983. There are believed to be over 42,000 of them across the UK’s road network today.

The big question raised is whether speed bumps are still fit for purpose, given reports of expensive damage caused to vehicles and suggestions that they increase air pollution in densely populated areas.

A brief history of speed bumps

22 April 1906 was the first known speed bump added to a road in Chatham, New Jersey.

Its aim was to reduce the speed of motor vehicles that had reached the capability of cruising at an average of 30mph in a residential area.

After nearly 50 years, the first rubber speed bump was created in 1953 when Nobel Prize-winning scientist Arthur Holly Compton created the “Holly Hump.” 

Delft, Netherlands, was the first speed bump installed in Europe in 1970, though it took another 13 years before they came to Britain as part of the original Highways (Road Hump) Regulations in 1983.

This permitted the installation of round-top humps with heights of up to 100mm, measuring 3.7 metres, on highways in England and Wales with a speed restriction of 30 mph or less.

Drivers began to refer to them as ‘sleeping policemen’ as more appeared on the roads in the eighties. The nickname was due to their ability to remind motorists they needed to be aware of their speed. 

How big are speed bumps and where can they be installed?

According to the most recent version of the Highways (Road Humps) Regulations 1999, all speed bumps must be at least 900mm long and between 25mm and 100mm tall at their tallest point.

No vertical face or material forming the speed hump may exceed 6mm, and the gradient of a speed bump must be no more than 1:10.

They can only be erected on roads where the posted speed limit is less than 30 mph, and they must always be positioned at a right angle to an imaginary line that runs down the middle of the road.

They cannot be installed within 20 metres of a railway track at a crossing if the speed limit is greater than 20 mph, or within 30 metres of a Zebra, Pelican, or Puffin pedestrian crossing.

They also cannot be placed within 25 metres of a bridge or tunnel where the structure crosses the path of a highway.

In locations without street lighting, speed bumps cannot be used if the posted speed limit is greater than 20 mph. To guarantee that cars can see the impediment in front of them, there should be at least three street lamps spaced no more than 38 metres away from one another.

This is due to the fact that traffic signs are only compulsory on roads where the speed limit exceeds 20mph.

How many speed bumps are there on Britain’s roads?

There are reportedly more than 42,000 separate speed bumps on more than 14,000 roads in Britain, spanning an estimated 2,000 miles of roadways, according to council statistics provided by the carmaker Citroen in 2019. 

Unsurprisingly, London Borough councils have the highest percentage of speed bumps per miles of road.

In the capital, eight councils account for the top 10 with the most speed humps.

Newham Council topped the list, which said the entirety of its 124 miles of roads has speed bumps installed on them.

It was followed by Southwark and Hackney, whose jurisdictions had 148 miles (or 71% of all routes) and 104 miles (or 69% of all routes) of speed-bumped roads, respectively. 

With traffic calming measures implemented on 17% of its roads, Norwich City Council topped the league table outside of London, followed by Portsmouth City Council (13%) and Bury Metropolitan Borough Council (12%). 

London boroughs with the most roads fitted with speed bumps

Councils outside of London with the most roads with speed bumps

Do speed bumps reduce road casualties?

Road safety experts claim that traffic-calming measures like speed bumps are one of the key reasons why deaths on UK roads are lower than in almost every other country. 

Nevertheless, they frequently cause complaints from drivers, particularly those who sustain car damage as a result of running over them.  

Ambulance drivers and the fire brigade have also hit out at them in the past.

Additionally, due to continuous braking and accelerating, poorly built bumps have been linked to accelerated road surface deterioration and an increase in car emissions.

Back in 2019, Steve Gooding, RAC Foundation director, stated that other forms of traffic calming, such as chicanes, should be considered ahead of speed bumps.

He told This is Money: “This proliferation of speed humps, speed cushions, speed ramp, speed tables, sleeping policemen – call them what you will – are put in place with the best of intentions. 

“However, they risk giving drivers, bikers and cyclists extremely uncomfortable rides especially if they fall into disrepair. 

“Road engineering offers other traffic calming solutions and these should be given equal consideration when the planners are at the drawing board.”

Do speed bumps cause damage to vehicles and how much will it cost to repair on average?

An investigation by Confused.com back in 2018 found that 22 per cent of motorists had experienced some form of car damage caused by the humps in the road. 

According to research conducted by the comparison website, the average cost to repair a car that was damaged by driving over a speed bump is £144.

Local authorities had to reimburse drivers £35,000 between 2015 and 2017 when it was discovered that many drivers had asked to be compensated for repair costs, with 45% of claims coming from London.

However, this is only the case when a speed bump is found to exceed the legal heights listed above.

The comparison website said the most common form of damage caused by speed bumps is tyre-related.

Do speed bumps increase air pollution?

Any traffic-calming measures that force drivers to continually change their speeds up and down would ultimately result in more emissions from vehicles.

However, the argument is that the small increase in pollution is offset by its impact on road safety. 

Michael Gove, who was the environment secretary at the time, stated in 2017 that municipalities should think about getting rid of them totally to “optimise traffic flow” and lower harmful levels of nitrogen dioxide.

He said that “improving road layouts and junctions to optimise traffic flow, for example by considering removal of road humps” should be considered ahead of the introduction of clean air zones in Britain and a ban on sales of new petrol and diesel cars – which have subsequently already launched across the country and been proposed (though delayed recently) respectively.

Tim Barlow, Transport Research Laboratory technical manager, told Transport Network in 2017 that traffic calming measures “can cause an increase in harmful tailpipe emissions and CO2”, with speed humps “tending to have the largest increases”. 

However, he said their primary job is to reduce speed to save lives in residential areas, which he claimed “don’t normally have air quality problems.”

For this reason, he thinks that speed humps and bumps have a negligible effect on the quantity of dangerous vehicle emissions produced overall.

In a joint letter issued to Mr Gove from the Campaign for Better Transport, Living Streets and Cycling UK said: “Local authorities should be able to demonstrate that any proposed alternative to speed humps is at least as effective in controlling speeds, preventing injuries and fatalities and improving public health for people of all ages and abilities, including children and other non-drivers.”