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PostPosted: Mon Dec 03, 2007 12:30 
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That's interesting, especially the following:
diy wrote:
... This reduced [the collision rate] by something like 200%

Reducing anything by more than 100% is very impressive :)


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PostPosted: Mon Dec 03, 2007 12:35 
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smeggy wrote:
Not necessarily. The key to this issue is use of hazard lights.
A true story, not exaggerated to fit:
I once had my immobiliser activate, without warning, when I was in L3 of the M3. We were all slowing down at the time (well it was rush hour) so I didn't immediately notice, so at the time I didn't quite know what was going on (I tried a push start, then the starter - which gave it away) so I did lose some speed. Use of hazard lights, judicious positioning (a toot wasn’t necessary but I was ready to use it) cleared me a path to the hard shoulder before I rolled to a halt.


I had something similar happen to me on the M6 a few years back, but in my case the accelerator cable snapped, while in lane 3. After a split second while the problem registered I hit the hazard light switch. I also had a passenger who made the decision to drop his window and use the up and down arm movement to indicate we were slowing down.

We got over to the hard shoulder with out any problems, the road was busy but not as busy as it could have been seeing as it was a Friday at about 5pm.


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PostPosted: Mon Dec 03, 2007 12:39 
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diy wrote:
This reduced the collision rate by something like 200%

How is this possible, without going into a negative collision rate, whatever that might be.

The conventional definition is 100% * (X2 - X1) / X1, which for -200% would require a negative collision rate.

The only way I know is to use the logarithmic definition of percentages.

percentage = 100% x Natural-Log(X2 / X/1)

-200% means that X2 is 0.1353 times X1, or a reduction of 86.5% by the conventional definition.

For small changes this produces the same results as the conventional method, but is much better when large changes are being considered, such as occur in some engineering calculations

A good interim method for reasonably large changes is 200% * (X2 - X1) / (X2 + X1), which is the first term of the Taylor expansion series for the logarithmic version, but for -200% that would give the result that X2 = 0
.


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PostPosted: Mon Dec 03, 2007 22:23 
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Best advert i saw regarding road safety and speed was this one from wmfs.net, cant find a photo of it but the text went thusly:

"Check your driving. Attitude and speed dont mix."

How much more sensible is that compared to the "speed kills" nonsense being espoused by the likes of weepej et al?

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PostPosted: Tue Dec 04, 2007 13:01 
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DeltaF wrote:
Best advert i saw regarding road safety and speed was this one from wmfs.net, cant find a photo of it but the text went thusly:

"Check your driving. Attitude and speed dont mix."

How much more sensible is that compared to the "speed kills" nonsense being espoused by the likes of weepej et al?


An improvement would be:
"Check your mindset. Poor attitude and driving don't mix."

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