Thursday, January 11, 2007

Are Speed Limits Safe

The short answer is, statistically, no. If you obey the posted speed limit you are statistically more likely to be in an accident. This has been proven in numerous traffic studies conducted, including an extensive one done by the U.S. Department of Transportation. That study focused on the effect on driver speeds when posted speed limits are raised or lowered. It was intended to prove that lower speed limits would increase safety and that higher speed limits would just cause people to driver faster and faster. The findings proved that none of that is true. What they did find out is that posted speeds do little to affect driver speeds; that when speeds are increased drivers do not necessarily increase to the limit; that higher posted speeds resulted in fewer accidents; and that lower posted speeds resulted in more accidents. The reason that higher speeds are safer and lower speeds are not is that most drivers intuitively know what is safe. They tend to driver at a comfortable safe speed regardless of what is posted. However, many drivers are conscientious about obeying the law and will not exceed the posted limit. Because of these two factors, the lower speed limits result in a higher variation of speeds. It is the variation, and not the speed itself, that makes for hazardous driving. As speed limits are raised, the law abiders are free to speed up to the rest of the flow.

What is truly surprising to the brainwashed masses is that, statistically drivers in the 90% percentile speed are the least likely to be in an accident, and the highest accident risk are the slowest 5% of drivers. Imagine that!

I would venture to guess the reason for this are vehicle types and driver competence; primarily driver competence. Faster drivers are generally driving higher performance vehicles. Higher performance vehicles (sports cars, sport coupes, etc.) are better equipped for the higher speeds. My SVT Focus is a safer car at any given speed that my Mustang GT. That's because it can stop better, turn better, and accelerate almost as well. So any situation that presents itself, I have more maneuvering ability at my disposal, therefore, a safer car.

Getting back to the safe speed limit issue. The traffic engineers at the DOT will tell you that the safest posted speed limit is the 85th percentile. So if the 85th percentile is the safest speed, why don't we use it? Revenue! Imagine how much money municipalities would lose if suddenly 85% of all the drivers on the road were now legal! They depend on traffic tickets for revenue so the speed limits are set artificially low. And it is all supported by huge lobbying efforts from insurance companies because traffic tickets allow them to raise rates.

1 comments:

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