An Excuse Is No Excuse
An Excuse Is No Excuse
December 30, 2013
Did you hear about the man whose wife ran away with a policeman? When speeding, he saw the flashing blue lights in his driving mirror and put his foot down even more because he thought they were bringing her back. How’s that for an excuse? Or what about the woman who assumed her speedo was deficient because she was at high altitude in the mountains? “It never does that at home!” Just two of the many excuses used to try and get away with a speeding offence.
No doubt any experienced traffic officer will be able to regale an audience with excuses, both clever and lame, that motorists use when caught going too fast. He probably will not reveal those where he was in the wrong - that’s a whole other story.
The trouble with an excuse is that there is no excuse. Sure, you might get away with it if your passenger is about to give birth, but that’s about it; and anyway, there’s never a pregnant woman around when you need one, although curiously there often is when you don’t. So, apart from matters of life or death your card will be marked. Names will be taken. Heads will roll.
Modern cars have very accurate speedometers but they don’t measure how fast a vehicle is going; they work on how many times a wheel, or axle or driveshaft rotates. Then, by the power of electronic wizardry, they convert that to what a driver sees on his or her gauge. There is a variable. New tyres make the wheel ‘bigger’, if that makes sense, as does increasing the tyre pressure. As a consequence the car will appear to travel further which will extrapolate to a greater speed. The same thing happens conversely. Thus, a small difference in wheel diameter gets exaggerated because the wheel is turning maybe six or seven times a second. Compounded, this can mean a difference of a few miles per hour. It’s a good idea to really learn the science of this. The boys in blue really love a good lecture at the roadside.
Some people prefer to use the information provided by their navigation devices. These work by measuring the exact distance covered over time by GPS tracking. They can be affected by signal quality and, in some instances, struggle to factor in steep hills. Whichever system a driver uses there is always a margin of error.
The law requires that speedos must never show less than the actual speed and must never show more than 110% of actual speed. To counter this, manufacturers tend to calibrate their gauges high, thus helping to save drivers from themselves. This is also why the cops allow a margin of error although the same can’t always be said of speed cameras which, as you know, have no soul. They just want the money.
Overall then, car speedos tend to read higher than sat-navs. It is not however the place of DriveWrite to recommend one device over another. If you remain resolutely below the advertised speed limit you should be ok. If all else fails you could try accidentally slipping a twenty pound note on the ground and ask, disingenuously, if the officer had perchance dropped it. This is an especially good plan if you need a bed for the night.
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