Big Brother? DOT to Require Vehicle Speed Limiters, But They Already Exist

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The Department of Transportation [DOT] has taken the first definitive step toward requiring devices to limit the top speed of heavy trucks, but both trucks and cars already have such devices, says public interest law professor John Banzhaf.

All that is necessary would be requiring the speed limiting circuits already in existing vehicle computers to be set to appropriate speeds, something which could be done almost immediately, says Banzhaf, who is a former MIT engineer and patent-holding inventor who has written on auto and vehicle safety.


Virtually every car – and presumably truck and bus – on the road today already has, built into its on-board electronic system, a high-speed cutoff circuit which prevents the vehicle from being driven at a speed greater than that programmed into its computer memory.

Unfortunately, the top speeds programmed into these systems usually exceed 120 mph, and are based upon the speed at which the tires will begin to disintegrate from centrifugal force.

But the top-speed setting can easily be reset by dealers, garages, and others to something far more realistic, almost as simply as computer users change the “defaults” in various fields on their programs.

If applied to smaller trucks and cars, especially those driven by young teen drivers, the savings in lives, in damage costs, and in fuel savings and environmental protection, would be far greater.

“For a young very inexperienced teen driver, especially one who has been admonished to limit his driving to city streets and not to exceed a speed of 55 mph, a parent could request the car dealer to reset the top speed to 60 mph – thereby virtually eliminating any possibility that the teen would exceed that limit, whether inadvertently, or because of alcohol, racing, or the urging of his teen passengers.”

“For more experienced teen drivers, parents could have the top speed of their child’s new car reset to a more reasonable 70, 75, or even 80 mph,” suggests Banzhaf.

Even an 80 mph speed limit, which is much higher than any teen would realistically need given current speed limits in most locations, would prevent the all-too-common accident where teens – sometimes while racing, sometimes while drunk, and sometimes at the urging of peers in the passenger seats – drives at 90 mph or above and puts not only himself and his passengers, but also everyone in other vehicles, at a very high risk of a very serious and often fatal accident.

A driver whose speed is no more than 80 mpg is obviously far less likely to have an accident than the same driver under the same road conditions going 90, 100, or even 120 mph. The differential between his speed and that of other vehicles on the road, the distance he would need to stop the car in an emergency, etc. are all much less, says Banzhaf.

Moreover, even if an accident did occur, it will almost always be less severe. In general, an accident at 120 mph is about 125% more severe than one occurring at 80 mph, even thought the first vehicle is traveling only 50% faster. This is because the severity of the accident is directly related to the energy the vehicle possesses, which is proportional not to the speed but to the square of the speed, explains Banzhaf

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