My theory is that some time in the 70s the state stamped out tens of thousands of “State speed limit 55” signs and doesn’t want them to go to waste.
How much would the speed limit have to be increased so that a driver’s average speed would be 10 mph higher?
I know the amount is going to vary considerably based on the traffic conditions, but in suburban areas where I mostly drive I’d think the limit would have to be a lot more than 10 mph higher for a driver’s average speed to be +10 mph.
Even interstate travel would not in many instances decrease travel time as much as some might expect. My husband drives frequently to and from suburban Chicago to suburban Milwaukee. The vast majority of the trip is on 94/294, where the speed limits are 60 or 70 mph. The total distance is around 90 miles, so you’d think a one-way trip would be 90 minutes or so, but if he can make it in under two hours he considers it a good trip. There are stretches where it doesn’t matter what the speed limit is – if you can average 40mph, you’re doing really well.
Driving in Los Angeles, speed limits are mostly aspirational. When the traffic happens to be sparse, I mostly just drive however fast feels safe, since I generally don’t know the limit on most stretches of road
It’s not speed that kills, but an incompetent,negligent or irresponsible driving.
If this is a safety issue let’s set the limit everywhere to 20mph or even 10mph for that matter, the slower the safer, right ?
This would be just a minor inconvenience compare to the number of lives potentially saved :rolleyes:
**cmkeller **
agree, either money or cheap political points or likely both.
FYI, with those speeds, you’ll be past an 80-foot long truck in less than seven seconds. What is your threshold for “dangerously long time”?
You got a lot of time on your hands I see.
I thought that traveling at different speeds was dangerous till I started driving in Europe. Now I think that statement is very american centric and not accurate. Also mandating that trucks drive slower than the speed limit, stick to the right but allow a 10 kph boost to pass other slower vehicles works great at keeping the traffic flow going.
The main problem with keeping everyone around the same speed is the typical American bunch up with good people driven to frustration trying to pass others who are blocking the flow of traffic. Now if you could get everyone to travel the exact same speed then we may have utopia.
Anybody going slower than me is an asshole. Anyone going faster is a maniac.
See? Easy!
Unfortunately that isn’t a joke in Minnesota during winter storms, where you will inevitably find yourself sandwiched between someone ridiculously cowardly in front of you, and someone manically reckless in back of you.
On many routes slowing down traffic does reduce the number of accidents, and/or the seriousness of accidents that do occur.
The reason it’s not arbitrarily low everywhere is because there’s a tradeoff with efficiency / utility of driving.
This is all very simple and obvious, except to someone who simply finds limits an inconvenience and so is trying to justify removing them all.
Sure; if I start my overtaking maneuver with my car literally touching the back of the truck, and then finish it with the truck initially touching the back of my car.
In a real life situation obviously I need to start a little distance behind the truck, and finish a big distance in front.
How long is safe? It’s arbitrary, but I’d say I wouldn’t want to be in the truck’s blind spot for more than 3 seconds, so between pulling out and being several cars ahead of the truck (and just adding distance before it’s safe to move in front of the truck) I’m thinking about 6 seconds.
Driving next to/passing a truck for 7 seconds seems to qualify as a ‘dangerously long time’, or I would put it as a unnecessarily and easily avoidable dangerous long time to be next to the truck and in the blind spot.
You might be assuming a multi-lane highway, but in some states the traffic laws specifically say you can exceed the speed limit when passing on a two lane (one in each direction) road where passing is allowed. Which even the most silly speed limit sticklers probably wouldn’t contest anyway, but throwing that out there. I don’t know if any specifically say you can do so on a road with two or more lanes in one direction.
But your point is reasonable and I speed up moderately to not be next to trucks for any more than the minimum time on two lane each way roads (creeping past them on a three or more lane each way road is OK). On one lane each way roads I floor it when passing, conditions allowing, or unless the slow vehicle is really slow, and my car is going as fast as it’s going when I release the pedal as I pull back to the right a safe distance ahead. On previously mentioned long all around US trip in big pretty and sluggish SUV, not that fast. In my own car, pretty fast. 
I’m a motorcyclist. I’m also fairly good at counting.
They know it, but don’t react to it. That way lies madness. (Although there is one method of setting a speed limit that surveys the actual speeds being driven on a road and sets the limit at the speed of 85% of the drivers.)
One thing to keep in mind is that if an engineer sets the speed limit incorrectly, accidents will result. With high accident rates come lawsuits. In lawsuits, if the speed limit can’t be justified by standard practices, the engineer and the municipality or government agency they work for are both up the creek. It encourages a person to keep good files with their calculations.
This is not a claim that no speed limits are ever set by politicians, but there are reasons besides speed traps that a limit might be lower than you’d like.
Interesting study from Arizona DOT.
Surprisingly, the data shows crash involvement is lowest for vehicles traveling 5-10 mph faster than average (for rural highways and freeways). It is a U-shaped curve, with slower than average speed and much faster than average speed having the highest crash involvement rates. It says nothing of crash severity. Would have thought the bottom of the curve would have been right at average speed, but its above average speed. Maybe the most skilled drivers feel slightly more comfortable, and drive a little faster? I dunno, found it interesting.
Additionally (again for rural highways and freeways), it shows the speed histograms for several sections of highway and it would appear that, in most cases, the speed-limit is about a full standard deviation below the actual observed average speed. (average speed is generally 5-10 mph faster than the limit).
Based on the data that shows correlation between speed delta and crash involvement, The report suggests that it prudent to set the speed limit in such a way as to minimize the observed speed deltas (lowest standard deviation).
Anyway the data would appear correct that for most drivers (meaning average speed drivers, and slightly faster than average speed drivers), people driving slower truly are assholes and people driving much faster are maniacs.
I’d say that it could be explained on the high side partly by the psychological characteristics of the very fast drivers, more prone to take risks like cutting people off (in addition to the regular reasons like more likely to slip on curves etc.)
It’s probably a combination for the slow drivers as well: it may be that some genuinely bad drivers drive slowly in recognition of this like you were saying. And it may also be that if you’re driving faster than average, you are less likely to have someone in your blind spot (or be in someone’s) for very long.
On third thought, I wonder if it has something to do with packets of cars travelling together. Slow cars are likely to be in and cause these even if they stick to the right hand lane, while fast cars are likely to just speed as fast as possible until they come up on the next packet (which they may or may not try to weave or tailgate through.) I wonder if cars that are going the average are more likely to create packets themselves by simply going at the same speed as the cars next to them. I know that on my latest trip up North, I wanted to usually go 5-10 miles per hour above the average, usually unsuccessfully, but my strategy was that if I saw a traffic packet coming up that took up all lanes and it was going within a few mph of my target, I slowed down to its speed at an extremely safe distance (such that I would certainly not have to brake, barring a sudden complete traffic stop) until it either cleared up or slowed down to an unacceptably low rate.
It only works over 25 mph, so that is taken care of already.
Even I know it’s OK to put on a reasonable amount of extra speed when passing. It’s better to get past the blind spots pronto.