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Is Every Speed Limit Too Low?

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Re: Is Every Speed Limit Too Low?

#191

Post by rrss1122 »

peatmoss wrote: post #15

This article ignores a lot of peer-reviewed literature from planning, public health / injury prevention, and civil engineering in favor of some folksy wisdom of a lieutenant cop. A good starting mental model is that vehicle speeds increase both the frequency and severity of crashes. The article weakly, and quietly made an argument that I do agree with. Namely, roadway design needs to accompany speed limits to ensure…

I would not trust the average person with higher speed limits. If they want to be adequate, safe, reasonable drivers, then they should drive at a slower speed and get used to it. I get the feeling that the reason most people who speed do it is because they overestimate the amount of time they'll have to get to where they're going and speed up when they see they're gonna be late.

Re: Is Every Speed Limit Too Low?

#192

Post by DatBear »

This article continuously states that speed limit signs have little to no bearing on how fast people actually drive, and it says Lt. Megge is actually arguing this. If it has no bearing on how fast people drive, and changing speed limits actually doesn't affect the speed of traffic like they say in the article, why are they changing them? Why are they too low right now? Why does the 85th percentile matter at all? If people pay as little attention to speed limit signs as is mentioned in the article, wouldn't changing them have no effect on safety whatsoever - be it lower or higher, better or worse?

Re: Is Every Speed Limit Too Low?

#193

Post by matdrewin »

peatmoss wrote: post #15

This article ignores a lot of peer-reviewed literature from planning, public health / injury prevention, and civil engineering in favor of some folksy wisdom of a lieutenant cop. A good starting mental model is that vehicle speeds increase both the frequency and severity of crashes. The article weakly, and quietly made an argument that I do agree with. Namely, roadway design needs to accompany speed limits to ensure…

You obviously didn't understand the article. It didn't say that speed wasn't dangerous. It said that speed signs only give us the illusion of safety because the majority of people disregard them anyways.

Re: Is Every Speed Limit Too Low?

#194

Post by matdrewin »

DatBear wrote: post #192

This article continuously states that speed limit signs have little to no bearing on how fast people actually drive, and it says Lt. Megge is actually arguing this. If it has no bearing on how fast people drive, and changing speed limits actually doesn't affect the speed of traffic like they say in the article, why are they changing them? Why are they too low right now? Why does the 85th percentile matter at all? If…

Cops would spend less time issuing useless tickets and concentrate on the real speeders.

A driver looking out for cops is a distracted driver. You shouldn't be worried if you are following traffic and going at a reasonable speed. That's not the case at the moment.

Re: Is Every Speed Limit Too Low?

#195

Post by alexmayyasi »

DatBear wrote: post #192

This article continuously states that speed limit signs have little to no bearing on how fast people actually drive, and it says Lt. Megge is actually arguing this. If it has no bearing on how fast people drive, and changing speed limits actually doesn't affect the speed of traffic like they say in the article, why are they changing them? Why are they too low right now? Why does the 85th percentile matter at all? If…

Please use ctrl-f to skip to this part of the article:

"So if drivers disregard speed limits, why bother trying to set the “right” speed limit at all?"

Then let us know what you think.

Re: Is Every Speed Limit Too Low?

#196

Post by logfromblammo »

gaius wrote: post #74
reitanqild wrote: post #67

Earlier quoted context omitted.

Mentioned this in another thread and I'm still looking for researh around this topic: A Dutch engineer once told me (back before 2004 I guess ) that they once raised the speed limit on the roads in Netherlands and found that counterintuitively, - average speed decreased. His explanation IIRC was that 1. once people break the rules it doesn't matter how much and 2. when speed limits felt more correct more people respe…

Let's not forget that the speed limit was never about safety. It was about saving fuel in an oil crisis.

It wasn't even about that. It was about appearing to do something about the oil crisis.

Actually saving fuel would have involved sitting down a dozen auto manufacturers and persuasively asking them to participate in a cartel to improve vehicle fuel efficiency without disproportionately harming any individual participant's competitiveness.

Instead, they ordered 250 million people to slow down. According to the article, only 10% are generally willing to do that consistently, and that just increases the collision rate.

So in the end, the 55 mile per hour speed limit wasn't about anything but ignorant management doing something with a high visibility to appear wise, leaderly, and decisive. But it actually just hurt everyone else. We've seen that story so many times, the details are practically unnecessary.

The sad thing is that the people that really need to learn the lessons of history are too busy trying to crank out more illustrative examples.

Re: Is Every Speed Limit Too Low?

#197

Post by logfromblammo »

saalweachter wrote: post #190
Spooky23 wrote: post #157

Earlier quoted context omitted.

There's a lot of truth to that. Many places use 7-10 mph over as a threshold. Smaller tickets always get plead down, and cops get measured by collars or tickets. I don't think skirting the limits has much impact on behavior as the limits go up. In my personal observation, I've observed little if any difference between highway driving on the Deegan Expressway in NYC (50 mph), i95 in South Carolina (70/75) or the mass…

Is the statistic NYC posts a lie? For a few years they've had signs up claiming that 80% of pedestrians hit at 30 mph survive, while 75% of pedestrians hit at 40 mph were killed. That seemed like a pretty good reason to have lower speed limits in pedestrian areas to me.

Seems like it would be a better reason to increase the physical separation between motorized and non-motorized traffic. I'd wager that more pedestrians would survive near 40 mph traffic if there were more energy-absorbing materials between them and the cars. The signs are probably just up to cut down on lawsuits directed toward the city.

The goal of improving roads is to increase the throughput of traffic. If it seems as though a problem could be solved by slowing down traffic, that's like solving a problem with a circuit by throwing a resistor into it. It may solve the immediate problem, but it will also reduce the overall efficiency of the circuit by converting energy into heat rather than usable work.

They could also put up signs that say 100% of the people who drive 40 mph reach their destinations 33% faster than those who drive 30 mph. It's just a distraction from the fact that solving the problem in a better way is more expensive than just blaming drivers and letting insurance handle the fallout.

Re: Is Every Speed Limit Too Low?

#198

Post by maxerickson »

logfromblammo wrote: post #197
saalweachter wrote: post #190

Earlier quoted context omitted.

Is the statistic NYC posts a lie? For a few years they've had signs up claiming that 80% of pedestrians hit at 30 mph survive, while 75% of pedestrians hit at 40 mph were killed. That seemed like a pretty good reason to have lower speed limits in pedestrian areas to me.

Seems like it would be a better reason to increase the physical separation between motorized and non-motorized traffic. I'd wager that more pedestrians would survive near 40 mph traffic if there were more energy-absorbing materials between them and the cars. The signs are probably just up to cut down on lawsuits directed toward the city. The goal of improving roads is to increase the throughput of traffic. If it seem…

You can quickly invent a distinction between a road and a street, where roads are indeed intended to maximize throughput but streets are intended to provide access.

So maybe those signs are on streets where throughput is not the primary goal, and where substantial barriers would interfere with people moving from their parked cars to the sidewalk and the like.

Re: Is Every Speed Limit Too Low?

#199

Post by logfromblammo »

maxerickson wrote: post #198
logfromblammo wrote: post #197

Earlier quoted context omitted.

Seems like it would be a better reason to increase the physical separation between motorized and non-motorized traffic. I'd wager that more pedestrians would survive near 40 mph traffic if there were more energy-absorbing materials between them and the cars. The signs are probably just up to cut down on lawsuits directed toward the city. The goal of improving roads is to increase the throughput of traffic. If it seem…

You can quickly invent a distinction between a road and a street, where roads are indeed intended to maximize throughput but streets are intended to provide access. So maybe those signs are on streets where throughput is not the primary goal, and where substantial barriers would interfere with people moving from their parked cars to the sidewalk and the like.

A line of parked cars between traffic and sidewalk is a substantial barrier on its own.

If you look at a high-traffic street where parking is prohibited, the Magnificent Mile in Chicago, you'll notice that there are gigantic concrete planters between the cars and the regular pedestrian traffic. Retail stores protect their entrances with concrete bollards. Construction zones protect workers from traffic with segmented Jersey barriers and water-filled crash barrels. Those are actual solutions.

But then you have suburban pearl-clutchers who lobby for a 15 mph speed limit and speed bumps in their cookie-cutter subdivisions, rather than actually making their streets safer for pedestrians. Or by replacing yield signs with stop signs. Those people don't realize that "change the law" is not always equivalent to "fix the problem".

Re: Is Every Speed Limit Too Low?

#200

Post by smileysteve »

bryanlarsen wrote: post #79
autokad wrote: post #73

Earlier quoted context omitted.

the article repeatedly mentioned: raising speed limits does not raise driving speeds on roads. humans are kind of strange in the fact that they drive at a speed they are comfortable with. also, while that (faster = crash more) may be true, its not the only thing going on. it may be the case (and one argued in the article) that driving speed differences results in more crashes.

"raising speed limits does not raise driving speeds on roads" I suspect that's a temporary effect. The speed people are comfortable at is mostly a learned phenomenon. The more they drive fast safely, the more comfortable they feel. Remember when you first started riding your bicycle? 10 mph was super fast and was super scary. And it is; that's faster than the speeds that the human body was evolved to support.

This reminds me, since standard speed limits were set, automobiles have drastically increased in their abilities. Rear independent suspension, lighter weight, disc brakes, radial and tubeless tires.

Just like on a bike, the first one was a heavy steel one with thick tires. Now, I'm riding a road bike that weighs a tiny amount and has dual compound tires.

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