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Why you shouldn`t do it, from a collision reconstr.. Posted by CrNiFe [Email]  (#408)  [Profile/Gallery]
(more from CrNiFe) on Fri, 8 Apr 2005 13:30:37
In Reply to: Cell phones and driving. OK--who does it??, Noel, Thu, 7 Apr 2005 14:51:55 Members do not see ads below this line. - Help Keep This Site Online - Signup |
ion perspective.
A text by Olson is the best one we have on perception and reaction times. A typical fast response to a situation is 0.6 seconds (quicklike a cat, as I say to the lawyers..) while an average response is 1.5 seconds, which most of you may be familiar with from articles.
The trouble with a cellphone is that although you are perfectly capable of doing routine non-reactive driving while talking, just as you can talk to someone in the car with you, if a non-standard situation comes up where you have to react, you first have to disconnect the cognitive activity of speaking, then perceive the threat, decide what to do (brake, steer, whatever) and finally do it. Your subconscious can`t be trusted to make the decision so your reflex may be to hit the brake... how can you tell if braking is the right decision?
This is the issue - we don`t have measurements for how long the p-r time is extended, but we do know that it goes up to 2.5 seconds for a legally impaired 80mg driver of average size. If we increase the p-r time by the same amount for a talking driver, the extra time is very possibly the difference between stopping safely and crashing, since at 60 mph you travel at 88 feet per second, and these extra 100 feet are added to your emergency braking distance. This is like having bad brakes and only finding out they are bad when you need them!
I have to use my cellphone, the handheld kind, but I don`t make a habit of it. I hate when my wife calls and starts into a detailed conversation when I am in traffic; it feels like a dangerous activity. I used to drive a standard 9-3 and talk on the cellphone, but I couldn`t have been doing a great job at both at the same time. That was before I became a collision reconstructionist and forensic engineer!
Cellphones are part of life. The handsfree units don`t eliminate the cognitive deficit that add to the p-r time, because you are talking, although it does make it easier to keep your hands on the wheel. Don`t abuse the phone privilege.
By the way, recently I saw a statistic that your chances of having a collision increase six-fold if you have young children in the car, because of their distraction value. As father of twins, I wonder if it is twelve-fold, and if it is, should I let my wife drive my 9-5 Wagon????
CrNiFe
99MY 9-5SW, 2.3lpt, 92000km
posted by 65.95.233...
, Fri, 8 Apr 2005 13:30:37 <-- Viewing This Message
, Thu, 7 Apr 2005 15:46:40, Thu, 7 Apr 2005 15:17:59
, Thu, 7 Apr 2005 15:54:14
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