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#1
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On Sun, 20 Jun 2004 22:37:33 GMT, Velvet
wrote in message : On the other hand, they drive less carefully when protected by airbags, abs and seatbelts. Not all of them do, ta :-) I don't think anyone is immune to risk compensation, although some people have a more realistic view of the merits of various safety aids than others. The comment refers to research done on drivers with and without ABS and seatbelts, which showed that they drove faster and less safely when using those devices. See Risk by John Adams. I don't rely on ABS to stop me quicker - I use it to even out the fact that the car in front probably has it and will stop quicker than I can if I don't have it... Er, actually ABS doesn't really affect stopping distances. It allows you to steer while braking. So it's not quite as clear cut that all the extra safety stuff makes people drive less carefully :-) It is, though. The taxi driver ABS trial was a near-perfect double-blind study and it showed that those driving ABS equipped cars accelerated harder, braked harder, drove faster and followed closer. Guy -- May contain traces of irony. Contents liable to settle after posting. http://www.chapmancentral.co.uk 88% of helmet statistics are made up, 65% of them at Washington University |
#2
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Just zis Guy, you know? wrote:
I don't rely on ABS to stop me quicker - I use it to even out the fact that the car in front probably has it and will stop quicker than I can if I don't have it... If you are relying on ABS to stop you, you are driving too close to the vehicle in front. Er, actually ABS doesn't really affect stopping distances. It allows you to steer while braking. Er, have you driven on snow with and without ABS? It certainly does affect stopping distance on ice or snow. -- Richard J. (to e-mail me, swap uk and yon in address) |
#3
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On Mon, 21 Jun 2004 09:43:35 GMT, "Richard J."
wrote (more or less): Just zis Guy, you know? wrote: I don't rely on ABS to stop me quicker - I use it to even out the fact that the car in front probably has it and will stop quicker than I can if I don't have it... If you are relying on ABS to stop you, you are driving too close to the vehicle in front. Er, actually ABS doesn't really affect stopping distances. It allows you to steer while braking. Er, have you driven on snow with and without ABS? It certainly does affect stopping distance on ice or snow. And in different ways. On ice, it will prevent lock-up of each wheel, increasing braking efficiency across the four wheels, decreasing stopping distance compared to a manually-controlled wheel. On snow, locking up the wheels can have the beneficial effect of causing a wedge of snow to build up in front of the locked wheel, which decreases stopping distance on snow compared to an abs wheel. -- Cheers, Euan Gawnsoft: http://www.gawnsoft.co.sr Symbian/Epoc wiki: http://html.dnsalias.net:1122 Smalltalk links (harvested from comp.lang.smalltalk) http://html.dnsalias.net/gawnsoft/smalltalk |
#4
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"Just zis Guy, you know?" wrote in message
Er, actually ABS doesn't really affect stopping distances. Yes it does. http://www-nrd.nhtsa.dot.gov/vrtc/ca...99-01-1287.pdf "For most stopping maneuvers, made on most test surfaces, ABS-assisted panic stops were found to be shorter than those made with best effort or full pedal applications with the ABS disabled" |
#5
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On Mon, 21 Jun 2004 10:42:13 +0100, "Grant Mason"
wrote in message : Er, actually ABS doesn't really affect stopping distances. Yes it does. http://www-nrd.nhtsa.dot.gov/vrtc/ca...99-01-1287.pdf "For most stopping maneuvers, made on most test surfaces, ABS-assisted panic stops were found to be shorter than those made with best effort or full pedal applications with the ABS disabled" Because people don't know how to brake. But the statement was overly simplistic, of course. ABS does not increase the power of the brakes, and does not increase the coefficient of friction. All it does is make it less likely that the driver will lock the wheels. Which, to a first approximation, is the same thing as "doesn't stop you quicker" - letting people believe that ABS stops you quicker is Not Smart in my view because in the end it doesn't affect the two main factors in stopping you. Actually the grip on my current car is so good that I haven't managed to trigger the ABS yet, even when I've tried. Guy -- May contain traces of irony. Contents liable to settle after posting. http://www.chapmancentral.co.uk 88% of helmet statistics are made up, 65% of them at Washington University |
#6
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On Mon, 21 Jun 2004 11:05:32 +0100, "Just zis Guy, you know?"
wrote (more or less): On Mon, 21 Jun 2004 10:42:13 +0100, "Grant Mason" wrote in message : Er, actually ABS doesn't really affect stopping distances. Yes it does. http://www-nrd.nhtsa.dot.gov/vrtc/ca...99-01-1287.pdf "For most stopping maneuvers, made on most test surfaces, ABS-assisted panic stops were found to be shorter than those made with best effort or full pedal applications with the ABS disabled" Because people don't know how to brake. But the statement was overly simplistic, of course. ABS does not increase the power of the brakes, and does not increase the coefficient of friction. All it does is make it less likely that the driver will lock the wheels. With abs, if one wheel is about to lock, the other three wheels can remain braking. To avoid one wheel locking up with non-abs brakes, all four wheels have to stop braking. -- Cheers, Euan Gawnsoft: http://www.gawnsoft.co.sr Symbian/Epoc wiki: http://html.dnsalias.net:1122 Smalltalk links (harvested from comp.lang.smalltalk) http://html.dnsalias.net/gawnsoft/smalltalk |
#7
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On Mon, 21 Jun 2004 19:32:55 +0100, Gawnsoft
wrote in message : With abs, if one wheel is about to lock, the other three wheels can remain braking. To avoid one wheel locking up with non-abs brakes, all four wheels have to stop braking. Indeed. But that's only relevant in specific conditions. I've already said it: ABS does not increase the braking performance of the car. It does compensate in some degree for poor technique, but even then you can fool it. Relying on ABS to "help you stop quicker" is stupid, and allowing people to think that's what it does is Not Smart. Guy -- May contain traces of irony. Contents liable to settle after posting. http://www.chapmancentral.co.uk 88% of helmet statistics are made up, 65% of them at Washington University |
#8
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On Mon, 21 Jun 2004 09:29:58 +0100, "Just zis Guy, you know?"
wrote: On Sun, 20 Jun 2004 22:37:33 GMT, Velvet wrote in message : So it's not quite as clear cut that all the extra safety stuff makes people drive less carefully :-) It is, though. The taxi driver ABS trial was a near-perfect double-blind study and it showed that those driving ABS equipped cars accelerated harder, braked harder, drove faster and followed closer. What particular form of psychic capability was reckoned to account for this, then ? As soon as any driver realised his vehicle had ABS, the trial failed the double-blind test, which demands that those taking part and the observers are both ignorant of the conditions. (I don't have any problem with trials that show that drivers fully aware of such features may "risk compensate" for them. But claiming to have double-blind trial results smacks of very dodgy science.) -- He said: Smile, things could be worse! I did! They were! Mail john rather than nospam... |
#9
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On Mon, 21 Jun 2004 10:53:47 +0100, John Laird
wrote in message : It is, though. The taxi driver ABS trial was a near-perfect double-blind study and it showed that those driving ABS equipped cars accelerated harder, braked harder, drove faster and followed closer. What particular form of psychic capability was reckoned to account for this, then ? As soon as any driver realised his vehicle had ABS, the trial failed the double-blind test, which demands that those taking part and the observers are both ignorant of the conditions. The condition being tested was "driver knowingly driving ABS equipped car". The drivers did not know which cars were fitted with measuring devices, and the observers did not know which measuring devices werefitted to cars with ABS. Guy -- May contain traces of irony. Contents liable to settle after posting. http://www.chapmancentral.co.uk 88% of helmet statistics are made up, 65% of them at Washington University |
#10
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On Mon, 21 Jun 2004 11:01:08 +0100, "Just zis Guy, you know?"
wrote: On Mon, 21 Jun 2004 10:53:47 +0100, John Laird wrote in message : It is, though. The taxi driver ABS trial was a near-perfect double-blind study and it showed that those driving ABS equipped cars accelerated harder, braked harder, drove faster and followed closer. What particular form of psychic capability was reckoned to account for this, then ? As soon as any driver realised his vehicle had ABS, the trial failed the double-blind test, which demands that those taking part and the observers are both ignorant of the conditions. The condition being tested was "driver knowingly driving ABS equipped car". The drivers did not know which cars were fitted with measuring devices, and the observers did not know which measuring devices werefitted to cars with ABS. That makes more sense, thanks. Of course, testing taxi drivers is highly dubious in itself ;-) -- Just a fake guitar player in the Monkees of life. Mail john rather than nospam... |
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