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Is Every Speed Limit Too Low?

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Re: Is Every Speed Limit Too Low?

#131

Post by seanflyon »

Theodores wrote: post #76
clairity wrote: post #57

Earlier quoted context omitted.

speed definitely increases the severity of crashes, but i'm not convinced that it increases frequency. even so, the #1 factor leading to increased frequency of crashes is distracted driving (sorry, don't have time to look up relevant links). if it exists, the correlation of accidents with speed is likely much weaker than with distractedness. if we really wanted to reduce motoring accidents, rather than regulating spe…

Maybe we should go back to Cadillac Eldorado 'bullet' style steering wheels (and no seatbelts) which really were as much use as a spike in the middle of a steering wheel.

It would reduce the number of crashes. Its essentially the same argument as your comment's grandparent, that we should make the roads narrower to reduce driving speed.

Re: Is Every Speed Limit Too Low?

#132

Post by [deleted] »

cheald wrote: post #118
softgrow wrote: post #111

Earlier quoted context omitted.

Dear readers, the Montana Speed Limit paradox is made up by an advocacy group with a barrow to push. Remember folks, trust but always verify. To quote from http://en.wikipedia.org/wiki/Talk:Speed_limit#Montana commenting on http://www.hwysafety.com/hwy_montana_2001.htm The source looks somewhat unreliable and biased. I looked up FARS data for 1998,1999,2000 for number of fatal-crashes in Montana (state), for (nhtsa)R…

I was looking for government numbers for those years, but didn't have much luck. Thanks for the FARS keyword - that looks like it should have the datasets I need! I'm going grab and parse them and see if there's an actual difference in the data. I somewhat doubt the data was made up, but it's possible that the roadway classifications were chosen in such a way that the datasets supported the point.

[deleted]

Re: Is Every Speed Limit Too Low?

#133

Post by softgrow »

cheald wrote: post #118
softgrow wrote: post #111

Earlier quoted context omitted.

Dear readers, the Montana Speed Limit paradox is made up by an advocacy group with a barrow to push. Remember folks, trust but always verify. To quote from http://en.wikipedia.org/wiki/Talk:Speed_limit#Montana commenting on http://www.hwysafety.com/hwy_montana_2001.htm The source looks somewhat unreliable and biased. I looked up FARS data for 1998,1999,2000 for number of fatal-crashes in Montana (state), for (nhtsa)R…

I was looking for government numbers for those years, but didn't have much luck. Thanks for the FARS keyword - that looks like it should have the datasets I need! I'm going grab and parse them and see if there's an actual difference in the data. I somewhat doubt the data was made up, but it's possible that the roadway classifications were chosen in such a way that the datasets supported the point.

No I think the so called paradox was made up, To verify:

  http://www.nhtsa.gov/FARS
  Select tab "Run a Query Using the FARS Web-Based Encyclopaedia"
  "Query Fars DATA" which takes you to 
  http://www-fars.nhtsa.dot.gov//QueryTool/QuerySection/SelectYear.aspx
  For each year 1998,1999,2000
    Select Query Year, e.g. 2000, then Submit
    In the top section Tick 
     “Roadway Function Class” 
     and “Month”, then Submit
    Select State: Montanta, and RFC Roadway Function 
    Class “Rural-Principal Arterial-Interstate”
    Select Univariate Tabulation
    Select Variable - Crash Month and “Show Zeros” Yes
Output

  1998-4,0,2,4,5,1,5,4,0,0,3,2,30
  1999-1,1,3,2,1,0,2,9,4,2,1,4,30
  2000-2,1,3,5,1,5,3,3,3,1,4,4,35
Then lose your doubts.

Re: Is Every Speed Limit Too Low?

#134

Post by dwd »

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…

It also ignores that speed limits are largely determined by what speed would allow you to safely stop if there was an road obstruction (traffic, animal, merging vehicles, etc).

Re: Is Every Speed Limit Too Low?

#135

Post by driverdan »

chadgeidel wrote: post #52
cfstras wrote: post #44

Disclaimer: I am from Germany. The speeding system we have here seems to make a lot more sense to me: On most highways, there is no speed limit. The only (theoretical) limit is the motor limitation of 155 mph (250 km/h), which can be taken out, but will almost always lead to losing any kind of motor warranty. In practice, there are limiting signs to 75 mph (120 km/h) for passages where the road is not good enough or…

I'm sure you hear this all the time, but it's my understanding that US drivers are not nearly as well "trained" as German drivers. Anecdata, yes yes. It's trivially easy to acquire and maintain a driving permit here in the States, and it shows. (US citizen here - I don't know about German drivers, but of course the skills of Germans are legendary. The automotive media tells us all German drivers are as skilled as Wal…

Ding ding ding! The solution is better driver training and mandatory retesting for all drivers at regular intervals. So many drivers of all ages are absolutely terrible. Everyone should be able to go 85 MPH on a six lane highway but you can't because there are so many bad drivers.

Driving is not a right and it should not be treated that way.

Re: Is Every Speed Limit Too Low?

#136

Post by peatmoss »

spott wrote: post #117
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…

Respectfully, you didn't read the rest of the abstract to the article you cite, and the next few sentences support what the article says: >Other studies looked at speed dispersion and found evidence that this is also an important factor in determining crash rate. Larger differences in speed between vehicles are related to a higher crash rate. Without exception, a vehicle that moved (much) faster than other traffic ar…

Respectfully, I did, and you're failing to acknowledge what I wrote in my initial posting.

> it is saying that speed differential is more dangerous than speed.

No it's not, the article is saying that a delta in speed is a factor in crash frequency. (And no, I didn't copy paste the whole abstract, because I was posting the part of the abstract germane to the quote I cited from the original article.)

> This is a horrible starting model. The severity of crashes is physics, but the frequency can't be looked at in isolation.

No, it's still a good starting model. If you read all the way to the end of that abstract, I think you'll see my point:

> Without exception, a vehicle that moved (much) faster than other traffic around it, had a higher crash rate. With regard to the rate of a (much) slower moving vehicle, the evidence is inconclusive.

So, much faster moving vehicles always had higher crash rates, while much slower vehicles... inconclusive.

There's a saying in statistics (George Box) that all models are wrong, but some models are useful. I think you'll find examples where speed isn't a problem, but those aren't the norm. If you're looking for a simple univariate model that goes a good long ways toward explaining vehicle safety, I'd challenge you to come up with a better one than what I've proposed here.

Re: Is Every Speed Limit Too Low?

#137

Post by Lagged2Death »

spott wrote: post #117
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…

Respectfully, you didn't read the rest of the abstract to the article you cite, and the next few sentences support what the article says: >Other studies looked at speed dispersion and found evidence that this is also an important factor in determining crash rate. Larger differences in speed between vehicles are related to a higher crash rate. Without exception, a vehicle that moved (much) faster than other traffic ar…

...however the few people that DO [pay attention to speed limits] cause accidents because it makes the differential speed much higher.

It's just an abstract that we're discussing here, I know, but the abstract absolutely, categorically does not say that. At all. You're guessing that's what it means.

Re: Is Every Speed Limit Too Low?

#138

Post by gabriel34 »

malchow wrote: post #23
wahsd wrote: post #7

Earlier quoted context omitted.

It doesn't even make any sense regarding highways. Ignoring their embarrassingly flawed standard for setting speed limits based on a percentile of speed limited traffic, there are so many other factors that go into the danger of traffic that are wholly and totally separate from speed. I would argue that the speed is exponentially less significant than the skill and training and experience of the drivers. Take a compa…

The data in the Wikipedia article you cite can also be sorted by road fatalities by 1 billion vehicle/kms. This accounts for variance in population, auto ownership, and amount of driving. Country and traffic fatalities per 1b veh/kms. United Arab Emirates 310 Brazil 55.9 Slovakia 24.5 South Korea 22.8 Bulgaria 19.1 Estonia 17.5 Cyprus 16.7 Czech Republic 15.7 Malaysia 13.8 Spain 8.5 New Zealand 8.3 Japan 8.3 Belgium…

The United Arab Emirates at 310 seems like an outlier but if you search for areb drift on youtube you can get a hang of what is really going on.

I live in Brasil, which, unsurprisingly ranks pretty high as well. Bad roads and unsafe vehicles explain part of the problem; but what I think accounts for the gist of it is something I haven't seen commented here: people speed because they want to be faster than other people. The speed limit merely makes this easier by limiting risk averse or society minded people.

I stoped driving long distances a year ago because it was stressing me out and because a car here is too expensive (compared to bus for long distances and taxi for short ones).

What I noticed in myself and in drivers around me was that traffic was regarded as a competition. Being faster was better. If someone was faster than you you'd be passive-aggressive towards him/her (mostly him). Brasil ranks 2nd (to last) on this list because of the way we view cars: they are really expensive, even in an expensive country such as ours. They are regarded as a life milestone, one of the main goal in our lives. They become a way of posing yourself as superior to the masses. This results in a more competitive traffic. Closing people off, tailgating and speeding (50% more than the limit - above this you risk losing your license and get fined for about $500) are the bread and butter of a good sum of our drivers. Our national speed limit is 120kmph (75mph).

Why do most people speed slightly? Is it because of the time they will save? I bet most don't even look at their watches while doing so. For a fixed distance, the speed x time is a hyperbole, which means diminishing returns for greater speeds for distances greater than the value of your speed. I posit that the gain is not time, but a better position at an acceptable risk in a competitive game we call transit.

Re: Is Every Speed Limit Too Low?

#139

Post by lfuller »

dfxm12 wrote: post #72
mwfunk wrote: post #45

Earlier quoted context omitted.

I'm also in the "drive a little under 10 over" camp, and I totally accept that once every 10 years (or whenever), I'm going to be in the wrong place at the wrong time and get a ticket for it. I'm OK with that. It's not fair, but it's well below the bar of meaningful injustice for me to really care about it all that much.

What's not fair about getting a speeding ticket when you are driving over the speed limit?

I believe it's implied that the limit itself is unfair.

Re: Is Every Speed Limit Too Low?

#140

Post by PantaloonFlames »

cpncrunch wrote: post #128
Spooky23 wrote: post #99

Earlier quoted context omitted.

End of the day, you shouldn't have laws that 80% of the population breaks during the ordinary course if business. I've found myself in vehicles towing trailers where 65 mph was about as fast as I could go. I continuously had cars passing me. If everyone is a criminal, something is wrong with the law.

They say 85% break the limit, but by how much? According to a 2003 UK study only 25% of people break the 30mph speed limit by more than 5mph, and only 20% break motorway speed limits by more than 10mph. https://en.wikipedia.org/wiki/Road_speed_limit_enforcement_i...

I think you have that backwards. The text in the article was:

> they want to set the speed limit so that 15% of drivers exceed it and 85% of drivers drive at or below the speed limit.

The citation you provided is roughly consistent with that.

The original article also said:

> Lt. Megge believes the compliance rate in Michigan to be well under 50%.

That's the only part that estimates rates of non-compliance. And it's not 85%.

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