Berzerker
Deity
speed limits are up to the owners of the roads to decide
Speed Limits - Yea or Nay?
- Thread starter Visorslash
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High speeds don't cause accidents, speed differential does. It's perfectly safe to drive 80mph if that's what the flow of traffic is. It's not safe when you have people doing 85 and grandpa is doing 55.
The reason most rural Interstate Freeways are set at 70 is because 18 wheelers can only effectively go 65 max if not fully loaded, it's even slower if they have a full load.
The reason most rural Interstate Freeways are set at 70 is because 18 wheelers can only effectively go 65 max if not fully loaded, it's even slower if they have a full load.
rugbyLEAGUEfan
Deity
You sure about that?
Yes it does, trucks can go fast, but it brutally kills fuel efficiency, which is why you don't see them driving faster. Trust me, truckers will drive much faster in a heartbeat if it wasn't so expensive.
Borachio
Way past lunacy
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Pretty much yes. You try driving 44 tonnes of ugly metal down a 1 in 20 slope.
rugbyLEAGUEfan
Deity
I don't see how the weight of the vehicle effects it's ability to accelerate more quickly downhill? But I'm not sure that's what you are saying anyway, so I'll just keep quiet till someone explains it all.
hobbsyoyo
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Guess what your speed differential with ground is if you're doing 85?
It's 85.
And at 85, you're far more likely to flip or veer off course wildly as any off center accelerations will quickly (almost instantly) put more stress into a car frame than it can handle which then turns into a situation where you hit a side rail or the ground at 85 or another car at some significant fraction of 85, which in turn leads to hitting the side rail or the ground at 85.
Even if you are going 85 and you are side swiped by a car at 80, you are transferring all of that stress in the suspension system which pushes against the ground. While perfectly level, the accleration between the ground and the accleration is just the force of gravity. But when acclerating off center (as in when nudged), and suddenly you're throwing part of the 85 mph velocity into the force vector acting on the suspension and car frame.
For the record, neither high speeds or speed differential cause accidents. Impacts cause accidents, faulty roads cause accidents, weather cause accidents, bad drivers cause accidents.
Velocity doesn't.
And I am really at a loss for why people think that just because you're hit with a low speed differential at a high speed that that won't likely cause more impacts at progressively higher speed differentials as you lose control.
Grendeldef
Trancerelic & coffeeholic
That would include Finland amongst few others. Instead of a precise amount of money the fine is measured in units (päiväsakko) and the value of a unit is proportional to one's income. Some minor offenses like parking tickets are same to everyone.
Speed limits in general are ok when there's a rational reason for one usually an urban area, a school, crappy road etc but on highways where a head-on collision is virtually impossible the limits are too low. Here 120 km/h but only 100 on winter time. Some roads have variable speed limits but those are only for lowering the limit due to fog, heavy rain, accidents and such. There has been some ideas to raise the limit to 130 or 140 km/h but it's not likely to materialize any time soon. I'd be willing to raise it above that on certain very good highways. Generally those who are causing troubles are either drunk or otherwise incapable of following what others are doing on the road or just don't care - speeding itself doesn't seem like a big problem.
German Autobahns are the nicest place one can drive and 200+ km/h is a cruising speed on a nice summer day. I've never driven faster than 250 due to electronic limiters but that speed didn't seem unsafe by any means. Sure, there're people driving much slower but very rarely on the same lane. Sudden lane swappers here seem much more dangerous than in Germany - people are used to looking at their mirrors and are aware of others few East-European truckers being a notable exception.
G
rugbyLEAGUEfan
Deity
There are enough numbers and Greek letters there for me to know I'm out of my depth. But I thought you mentioned the truck would accelerate faster due to it's mass, and I thought mass doesn't affect the rate at which a body falls. I do however get that the collision is with a greater force.
GhostWriter16
Deity
While I see the point of tying the fine to the wealth one has, particularly so the rich can't just "Get away with" things that are clearly wrong but clearly don't deserve jail time, but there's something perverse about a fine for speeding being in the hundreds of thousands of dollars.
Ziggy Stardust
Absolutely Sane
Bit hesitant to reply, because maybe I'm reiterating your point.
High speed differential reduces reaction time, so it can be a big factor whether an accident is avoided or not.
hobbsyoyo
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No dude. Gravity accelerates all masses equally. Like the feather and the bowling ball (?) drop on the moon. Mass has nothing to do with the acceleration of gravity at all (well the mass of the Earth does, and if the object being dropped were massive enough to attact the Earth, then it would, but that's beside the point).
The reason why trucks accelerate down slope so bad is because they don't have the brake power to properly decelarate on an incline. They gather a huge amount of momentum on that downhill trip and it's really hard to counter it.
rugbyLEAGUEfan
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Yaayyyy Hobbs. I just knew I was onto something.
hobbsyoyo
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I'm pretty sure that is what he meant, and I explained why I think he was wrong in the post above.
My apologies if I misread you Borachio.
There's something perverse in a multimillionaire paying a lower % of income to taxes than my wife and I do.
Dude, that's absolutely true as well and another thing people (myself included) overlooked. I was so wrapped up in the physics of a car crash I didn't even think about that.
rugbyLEAGUEfan
Deity
Unquestionably the rate of acceleration of falling bodies is unaffected by mass (strolls back into thread puffing out chest).
hobbsyoyo
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Nope (trying not to sound smug, I promise). It means more momentum and more kinetic energy.
You will be going faster at the bottom of the hill than at the top and have more momentum. But you will not accelerate to that speed faster than a golf ball or a light car would traveling down that same hill.
In fact, trucks are so un-aerodynamic that a golf ball or light car will probably accelerate faster due to their better drag coefficients.
But they will not have anywhere near the energy that your big rig will have. All that momentum means it's very hard for your brakes to do enough work to slow you down while a small car's brakes have much less energy to deal with.
Because the cars that are on the same hill have brakes that can slow them down a lot quicker than you can. So when they start to feel uncomfortable going down the hill, they tap the brake and slow down quickly.
Now when your big rig is going down the hill, you mash the brake continuously and you aren't going to slow down very fast. Eventually, you are going to sail right past the car simply because you can't slow down and they can.
That's why those special truck lanes are so important in the mountains because trucks have a hard time controlling their speed both uphill and down.
Think of it this way for going down a slope:
Higher mass doesn't mean higher acceleration.
But higher mass does mean lower deceleration. Lighter car = faster deceleration = you go faster in a truck because car drivers don't want to die and slow down. You don't have that choice.
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