London, 12 Jan 2000.
For immediate release.

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Press Release

Speed Limiter Devices Signal a Return of The Red Flag Act
Scheme to force external control of vehicle speeds will cause road carnage
- and Leeds University research actually shows this!
Recent reports of satellite controlled speed limiters which prevent cars from exceeding speed limits should be treated with alarm by drivers and vulnerable road users alike.

External control of vehicle speeds will result in drivers simply travelling as fast as the limiter will allow, without giving any thought to their surroundings. Since many accidents result from drivers going too fast for the conditions but still within the speed limit, an increase in this kind of crash is inevitable.

Of even more concern is the likely effect on both driversí concentration and skill levels, which will lead to many more accidents, especially those involving cyclists and horseriders who rely on drivers seeing them and giving them room.

The detail of the Leeds University research, summarised below but strangely not highlighted in media reports on the issue, already clearly demonstrates the negative effects of speed limiters on driver behaviour and accidents predicted by the ABD.

When accidents increase as a result of these devices, then allowed speeds will be cut to a crawl in an attempt to get deskilled drivers relying blindly on the limiter to be as safe as intelligent drivers at much higher speeds.

These devices, which could become reality within ten years, will use existing Global Positioning Satellites to fix the cars location, and compare this with a on-board database of every speed limit in the UK, mechanically preventing the car from exceeding the speed limit.

"This whole programme is based on the principle that breaking the speed limit is the biggest cause of accidents - but this view is totally false," says ABD Spokesman Mark McArthur-Christie. "Most accidents are caused by poor concentration or failure to recognise hazards, and speed reduction measures often make these worse. This is why road safety largely stopped improving during the 1990ís, when the focus was almost exclusively on speed reduction."

Those responsible for developing this system make the grandiose claim that it will save the lives of no less than two thirds of road accident victims. Since recent research into accident causation by the TRL, in conjunction with several police forces, showed that only 4.3% of accidents were primarily caused by speeding, these claims should be treated with nothing less than contempt.

It will not be existing limits that are enforced by these new devices. The leader of this Leeds University project, Oliver Carsten, has stated that, in his view, the optimum speed for built up areas is 12kph - a sedentary 7.5mph. This will indeed be a return to the notorious Red Flag Act, whereby a man with such a tool was expected to walk in front of horseless carriages to warn of their approach at the turn of the last century.

"They are perpetuating the road safety errors of the 1990ís," continues McArthur-Christie. "When speed reduction measures fail to cut accidents, the response is to tighten them further instead of ditching them in favour of intelligent measures to improve road user competence. If this goes on, we will end up with no more than a hi-tech Red Flag act, with drivers reduced to motorised teletubbies blundering around crashing in to anything that moves."

If the researchers at Leeds University want to do something useful, perhaps they could convert this technology to give advance warning of hazards such as accidents, ice or even dangerous bends, working with drivers to give them the information they need make them better drivers rather than undermining their ability to control their vehicles properly.

ABD Chairman Brian Gregory sums up:

"If somebody can produce an automated system that can take full control of a vehicle, and do it more sucessfully than a properly trained, attentive driver, then by all means install it in our cars. Until this point is reached, any attempt to remove one aspect of car control from the driver is likely to result in disaster."


The results of the simulated driver behaviour study produce some alarming results. The experiment tested the effect on driver behaviour in three ways:

  1. Traffic light violations
  2. Following distances
  3. Driving on the motorway in fog
The experiment was carried out under four conditions of car control:
No speed limiter(driver has complete control)
Advisory dynamic(display shows advisory maximum speed, dependent on conditions)
Mandatory dynamic(speed limited according to the conditions)
Mandatory fixed(speed limited to posted speed limit)

In testing traffic light violations, drivers were placed in the 'dilemma zone' on the approach to traffic lights. The following violation rates were found:

No speed limiter33%
Advisory dynamic46%
Mandatory dynamic40%
Mandatory fixed53%

You might think that is pretty damning of speed limiters, and you would be right! But it gets worse -in the following distance test, which was done for urban and rural roads separately, the percentage of time spent at a headway of less than one second from the vehicle in front was:

No speed limiter0.47%0.00%
Advisory dynamic6.78%0.00%
Mandatory dynamic10.80%5.50%
Mandatory fixed8.31%6.10%

If that isn't bad enough, there are the results of the motorway fog test.
Drivers with the advisory and mandatory dynamic systems were advised or compelled respectively to not exceed 50 mph (80 kph). The actual mean speeds along the motorway were as follows:

Speed limit50 mph
No speed limiter54.99 mph
Advisory dynamic49.50 mph*
Mandatory dynamic (at 50)47.71 mph
Mandatory fixed (at 70)59.67 mph
* i.e. they stuck to the advisory limit without compulsion!

So with a speed limiter fixed to the limit, drivers travelled faster in hazardous conditions.

The number of 'collisions' experienced by the four groups were as follows:

No speed limiter1
Advisory dynamic0
Mandatory dynamic0
Mandatory fixed3

It is quite obvious that taking control away from the driver would have appalling consequences for driver behaviour, which are bound to increase accident rates, possibly quite severely.



Notes for Editors