Could autonomous vehicles eliminate the need for speed bumps?

Last year, a freedom of information request (FOI) by Citroën has revealed that there are now 42,000 speed on the UK’s roads. The request showed that London is the speed bump capital of Great Britain, with 8 of the top 10 councils in terms of bumps per mile. Speed bumps were introduced to the UK in 1983 under The Highways (Road Humps) Regulations. Since then they have been plagued with controversy. In 2016 a poll conducted by the AA found that 62% of its members loathed the contentious bumps in the road, also known as sleeping policemen. This was even higher than the 59% of respondents who said they were wound up by roadworks.

Speed Bump Sign

The most contentious of traffic-calming measures

Noise and pollution

Drivers and driving organizations claim speed bumps have many disadvantages compared to other traffic calming measures. Opposers say they divert traffic to alternative residential streets, do damage to vehicles, and are uncomfortable for drivers and passengers.

Other problems cited include an increase in noise and pollution. Various studies have shown that speed bumps can increase noise by up to 6 dB depending on the size and design of the bump. However, noise levels from bumps are also dependant on the style of driving and in some cases with the right driving conditions they can actually decrease noise levels.

Research by scientists at Imperial College London showed a diesel car emits 98 per cent more nitrogen dioxide when driving over speed bumps compared to narrower and shallower “road cushions”. A petrol car produced 64 per cent more nitrogen dioxide, 60 per cent more carbon monoxide, and 47 per cent more particulate matter.

In an interview with the Telegraph, Professor Alastair Lewis, Professor of Atmospheric Chemistry at the University of York, explained, “On the acceleration cycle you get combustion pollutants. On the braking part of the cycle you get non-exhaust emissions caused by friction on brake pads and tyres which throws out fine particles into the air – this happens even if you drive an electric car.”

And back in 2003, the London Ambulance Service claimed speed bumps reduced the response time of emergency vehicles. They said research had shown that delays in London alone accounted for an extra 500 deaths a year.

Reducing the need for speed bumps

In 2011 the UK government announced measures that allowed councils to reduce the need for speed bumps in 20mph zones. The proposal was part of an initiative to cut some of the bureaucracy councils face by expanding the list of specified traffic measures available. These included allowing symbols painted on the road instead of on upright signs, making use of repeater signs and mini-roundabouts, and allowing local authorities to use signs on just one side of the road, where appropriate, such as outside schools.

In 2017, the government went even further, with the then Environment Secretary, Michael Gove, putting forward plans for councils to scrap speed bumps altogether as part of an initiative to reduce pollution.

Mr Gove said town halls should prioritize “improving road layouts and junctions to optimise traffic flow, for example by considering removal of road humps”.

Road safety campaigners called the idea “daft and irresponsible” and warned that the removal of speed bumps would increase the danger to children while having little impact on air pollution.

Living Streets, a charity that campaigns for everyday walking and less reliance on cars, said that removing speed bumps would deter children from walking to and from school. This is in turn would mean more children are taken to school by car which would produce more pollution. In an open letter to Mr Gove they wrote, “Well designed and well-maintained humps and other devices can smooth traffic flows and keep speeds down, which should improve air quality. There is a case for spending more on these measures, not ripping them out.”

Virtual speed bumps

In November 2014 Transport for London (TfL) trialled using virtual speed bumps to slow down traffic on the capital’s roads. The initiative used 2D black and white patterns painted on the road and perspective tricks to create the illusion of speed bumps to oncoming vehicles.

Nine months after the initial trial on the A117 in the borough of Newham average speeds had reduced by 3mph. By 2017 the idea had been rolled out to 45 locations in London.

Philadelphia Virtual Speed Bump

A virtual speed bump in Philadelphia 

London was not the first city to test virtual speed bumps. In 2008, as part of its “Drive CarePhilly”, Philadelphia’s Department of Streets laid down a fake speed bump in a Northeast neighbourhood. The fake bump is a flat piece of plastic burned into the road with blue, white, and orange triangles that look like 3D pyramids to oncoming traffic. The speed bump include glass beads for visibility at night and costs a fraction of real speed bumps.

Autonomous cars and speed bumps

In 2015 Hyundai filed a patent with the US Patent and Trademark Office for detecting speed humps. The system uses technology that is already available in cars today; GPS, a camera and various sensors. The technology detects the speed bump and measures its width, height and curvature.

It then calculates the speed the car needs to be travelling at to drive over the bump safely. If the driver is going too fast the system will issue an alert to warn the driver to slow down. It can detect ‘virtual’ or fake speed bumps painted on the road and ignore them.

Hyundai Speed Hump Patent

Hyundai patent for detecting speed bumps

Today, this seems like a problem that doesn’t need to be solved. However, while Hyundai makes no mention of this in the patent application, the technology could be very useful in autonomous vehicles. Instead of sending a warning to the driver, it would automatically slow the car down.

Of course, as more vehicles become autonomous the need for real or fake speed bumps would be reduced or eliminated altogether. This would mean massive changes to road infrastructure, and the chaos that could potentially ensue, as well as the cost, is likely to be even more controversial  than those bumps in the road.

Speed bump advice from the AA

  • Go slow on the approach, using brakes, and then let the vehicle’s momentum take the vehicle over the hump
  • With half bumps, keep the vehicle stable by straddling the bump equally
  • Smooth driving in humped areas is better than harsh acceleration and braking between them
  • Humps indicate the need for increased driver awareness as they tend to be placed in higher risk areas
  • Route planning to avoid road-humped residential streets can reduce their impact on cargo and passengers