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DigiNut
You kids get off my lawn!

Registered: Dec 2002
Location: Toronto, Self-proclaimed Centre of the Universe
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| quote: | Originally posted by StereoPrincess
Even half a meter of stopping distance could mean life and death. |
Many people say this without realizing it's a self-defeating argument.
Look at the numbers - 30 km/h is 8.3 m/s, 40 km/h is 11.1 m/s, and 50 km/h is 13.9 m/s. So let's take two situations - one with the driver going 30 and the other going 40. In the first case, a 6-year-old darts out in the street, which we assume takes about 2-3 seconds to do since the kid is using his feet and not teleporting instantly onto the street. During those same 2-3 seconds the driver reacts and slams on the brakes and manages a stopping distance of 6 m (the average stopping distance for a car going 30), which we will presume is in your "every millisecond matters" category and is precisely one inch away from the playing child. Well, if that same driver had been going 40 instead of 30 and not hit the brakes at all, the car within 1.5 seconds would have travelled 16.7 m during the same time, which would be a full 10.7 m further during the instant before the kid stepped onto the street. In layman's terms, the kid would have ended up jumping on the street behind the passing car, long after any real danger.
So in reality, if both drivers started from the exact same instant, the driver going 40 would not have been any more likely to injure the kid than the driver going 30. From a purely statistical perspective, the 40 driver spends 33% less time on the road which decrease his overall chances of getting into an accident. It's not correct to start the timing from the instant the kid actually lands on the road because that assumes neither driver is paying attention. If the drivers aren't paying attention, we have much bigger problems than speed.
The mitigating factor here is reaction time, NOT stopping distance, which is the main reason it is safer to drive slower in some cases (i.e. residential streets) - if reaction time stays constant around 1 second, then a driver going 40 is at greater risk if and ONLY if something suddenly (within that 1 second) pops up precisely between 8.3 and 11.1 m in front of him. It will not make ANY difference if something pops up closer than 8.3 m or further than 11.1 m. So we're placing all bets on the chances that a school child will step into that exact distance range and do it quickly enough for the driver not to notice in time - the chances of this happening are VERY low. Stopping distance only really matters on the highway when there's a possibility of a pile-up due to an accident ahead of you. Reaction time CAN be an issue in residential/school zones though if someone is driving VERY fast - if someone is going say, 70, they'll travel nearly 20 meters in that 1 second of reaction time, which leaves a HUGE margin for accidents to happen. The difference between 30 and 40 though, is quite small.
It's easy to look at a near-miss and say "if he'd been going just a tiny bit faster, he'd have hit the kid". But at the same time, if the kid had jumped out 1 second earlier, then the kid would have been hit by the slow driver and a faster driver would have been fine. It's all a question of statistics.
It's been identified several times that ordinary people have really terrible instincts when it comes to statistics and probability (read Innumeracy, or if you're too lazy or busy to do that, just think about how much money casinos make). People who get up-in-arms about road safety often don't understand the dynamics of how these situations work. Yes, it's true, you can look at an ISOLATED incident in HINDSIGHT and say that someone would have been safer if they'd been driving slower - but the probability a posteriori (after the fact) of an event happening is always 100%. A priori (before the fact), it is equally probable that that deer would have ran out onto the street 1 second earlier.
So be careful when saying that every kilometer [per hour] counts - reality is not quite so simplistic.
___________________
My party schedule:
2009-02-21 - DJ Attention @ I'm So Popular
2009-06-18 - DJ Annoying @ People Need To Know Where I'll Be
2012-11-32 - DJ Insufferable ɸ Or At Least the Stalkers I Complain About
2048-06-66 - Spastic & Whocares ¶ Although I'm Actually Flattered
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Aug-13-2004 19:13
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dallastar
~Dance~Sing~Floss~Travel~

Registered: Jul 2003
Location: 333 Half Evil ™
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Aug-14-2004 00:58
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Jayx1
Prime Minister of TOTA
Registered: Feb 2003
Location: The Socialist People's Republic Of Canada
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just curious but how is photo radar supposed to stop drunk driving and reckless driving?
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Aug-14-2004 14:02
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DigiNut
You kids get off my lawn!

Registered: Dec 2002
Location: Toronto, Self-proclaimed Centre of the Universe
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Margs - I don't think there's a whole lot of difference to a pedestrian who actually gets hit by a car if the car is going 30 or 40. I see where you're coming from and that's why I said yes, I can see this happening in school zones, but only for speeds that are really dangerous and not 5 km/h over the posted limit (most car speedometers aren't even guaranteed to be that accurate!)
| quote: | Originally posted by Flec
cash grub or not, DONT FUCKING SPEED
how simple is that? |
It's not simple at all. That's like saying "don't steal" to someone who collects MP3s. Sure, everyone knows that CC fraud or stealing a computer from Future Shop is wrong - but there are certain grey areas where it is dubious whether or not the law is protective or oppressive.
For speeding, posted limits apply to specific conditions, and even then they are under-posted on 400 series highways (most states are 110-120). "Speeding" is dangerous when you mean "driving way too fast for the current conditions", but not "speeding" in the sense of "driving faster than the posted limit" - it's usually safe to drive 130 on the 401 but there are certain times when I would not go faster than 40 or 50, like in the torrential rain we were experiencing a few weeks ago. People who drive 130 in dry sunny weather and light traffic are usually safer drivers than those who go 100 in torrential rain or huge traffic jams.
I'm pretty sure everyone here has done something illegal at least once. Speeding is one issue where the relevance of the law is actually in question, but the majority of people have a poor understanding of probability and statistics and just listen to whatever the government tells them. You can tell people to "don't speed" all you want, but they're still going to do it. I'd say about 85% of people know what speed is safe without "help" from a posted limit - at least, that's the number that traffic engineers from all over the world use. Hell, anybody who's gone to driving school should know that they'll tell you to "go with the flow" regardless of whatever the speed limit is - driving slower than everybody else on the road is not safe, it fucks up the traffic patterns and induces road rage.
___________________
My party schedule:
2009-02-21 - DJ Attention @ I'm So Popular
2009-06-18 - DJ Annoying @ People Need To Know Where I'll Be
2012-11-32 - DJ Insufferable ɸ Or At Least the Stalkers I Complain About
2048-06-66 - Spastic & Whocares ¶ Although I'm Actually Flattered
9999-45-81 - Tweaker Gimp ☼ I Probably Won't Even Go To This But I Have To Make Sure I Fill Up All The Available Space Here
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Aug-14-2004 18:12
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