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Do Speed Limiting Devices Improve Road Safety?

By: Kevin Watson MSc - Updated: 21 Nov 2018 | comments*Discuss
Speed-limiting Devices Accidents Fuel

In 2008, the now defunct Commission for Integrated Transport (CfIT) wrote a report about speed-limiting devices. CfIT said that the government should encourage motorists to fit speed-limiters to cars on a voluntary basis. The aim would be to:

  • Reduce accidents
  • Save lives
  • Help drivers avoid fines and licence points
  • Reduce fuel consumption
  • Cut carbon dioxide emissions


Speed-limiting devices are already in common use for fleet vehicles. British Gas vans, for example, cannot go faster than 70 mph. CfIT proposed something more radical, however. It wanted councils to create digital road maps. These maps would contain the legal maximum speed of each road.

A speed-limiting device in a car would use GPS (Global Positioning System) technology to confirm the vehicle’s position. Once confirmed, the device would limit the car to the road’s maximum speed. If the driver tried to exceed this, the brakes would automatically cut in.

Safety Figures

CfIT said that speed-limiting technology would reduce serious and fatal road accidents. The reduction would be 29%.British Gas agreed with CfIT that speed-limiters reduce accidents. It said that its 70 mph restriction had improved road safety for its drivers. British Gas added, however, that speed-limiters were just one of a series of road safety initiatives that it promoted.

Alternative Views

Since the CfIT report, the government has not developed a strategy based on speed-limiting devices. Furthermore, other groups have given alternative views. Road safety campaigners such as those from Safe Speed have raised concerns. They are against the idea of an electronic device rather than a driver controlling a car.

The campaigners say that speed-limiting devices encourage people to pay less attention to driving. They also object to what amounts to electronic policing.


The Motor Industry Research Association (MIRA) has another view. It believes that speed-limiting devices increase safety; but it wants them on all vehicles.

MIRA’s concern is that voluntary use of speed-limiting devices, as proposed by CfIT, could create rather than cut accidents. A car fitted with a speed-limiter might, for example, pull out to overtake a series of vehicles. The speed-limiter would then cut in and hold the car back.

When this happens, the speed-limited driver would have to pull back to the left, particularly if there is oncoming traffic. The cars the driver is trying to overtake would have to slow down to allow the car in. As a result, the cars would bunch up. This could create a situation where an accident is more likely to occur.

If all vehicles have speed-limiting devices, MIRA argues, this situation becomes less risky. This is because all drivers would be familiar with speed-limiting technology. Overtaking would then become less common. And when overtaking does occur, drivers would take account of the speed restriction.


CfIT did consider the issue of overtaking. It suggested that drivers with a voluntary speed-limiter should have an override feature. This could be in the form of a button on the steering wheel.

The principle would be similar to that of interrupting a car’s cruise control. Drivers with speed-limiters could choose to overtake at speeds in excess of the legal limit.


The debate about speed-limiting devices on cars is far from settled. For the time being, those who favour full driver control of a car hold sway. But a need to reduce accidents, fuel consumption and emissions may encourage the government to look at the issue again.

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Can you express in words reading 3.00m-1 from exhaust emission result for diesel car and explain thanks would like to know how to pronounce above figure
Diesel doc - 21-Nov-18 @ 3:34 PM
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