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

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)

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

"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"

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

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

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

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...

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

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...