Is Every Speed Limit Too Low? • Hacker News Board

Re: Is Every Speed Limit Too Low?

#31

Post by 67726e » Mon, Aug 04, 2014, 7:38 PM UTC

arthurdenture wrote: post #14

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 USA's per capita automobile death rate is over twice as high as Germany's, in spite of speed limits in general being lower in Germany and there being far more and more generous roads in the USA. [...] Statistically speaking though, you would think that more driving on wider, bigger roads and in less densely populated areas would lead to less accidents and not more. The relationship between forgiving roads and s…

Given the large differences in standards, training, and attitudes about driving in the US vs. Germany. I would say calling American drivers as a whole, shittier, than German drivers is a not too far off assessment.

Re: Is Every Speed Limit Too Low?

#32

Post by peatmoss » Mon, Aug 04, 2014, 7:39 PM UTC

tux1968 wrote: post #18

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…

There is conflicting evidence on the matter. A local (Vancouver) video[1] circulating here had some strong arguments that our speed limits are kept needlessly low. If you're interested in such things, it's a well done video and worth the 15 minutes it takes to watch. [1] http://www.vancitybuzz.com/2013/09/speed-does-not-kill-vanco...

Wrote my masters thesis in transportation planning on traffic calming. Peer review or it didn't happen. Not that peer review is perfect, but a viral video with an obvious agenda doesn't do it for me.

Re: Is Every Speed Limit Too Low?

#33

Post by thaumasiotes » Mon, Aug 04, 2014, 7:39 PM UTC

colanderman wrote: post #20

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…

I don't think you're disagreeing with the article's premise. Your "horrible drivers" can include people who either drive far too fast or far too slow, thus creating a speed differential. Lt. Megge's idea concedes that you can't get the fast drivers to slow down, but maybe you can get the slow drivers to speed up. (Aside, I agree 100% about more rigorous licensing. I spend 3 hrs on the highway each day; easily 80% of…

> driving slow in the left lane, passing on the right

Is this two problems or one?

Re: Is Every Speed Limit Too Low?

#34

Post by danielq » Mon, Aug 04, 2014, 7:46 PM UTC

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…

Interesting to see Germany with 4.9 below the US with 7.6. In Germany, long stretches of quite a few Autobahns do not have a speed-limit at all. There are, of course, other differences between driving in the US and in Germany.

source: I have been driving in both countries for more than 8 years; moved to the US little more than 8 years ago.

Re: Is Every Speed Limit Too Low?

#35

Post by mnarayan01 » Mon, Aug 04, 2014, 7:47 PM UTC

incision wrote: post #24

mcdougle wrote: post #8

Earlier quoted context omitted.

You do raise a good point. I know that, when I started driving, my dad taught me a neat trick: drive 8.5 mph over the speed limit, and you'll never get pulled over. That's (supposedly) because a ticket for anything less than 10mph is simply not worth it for the cops. If you go any more than 8.5mph over, though, you might accidentally cross that 10mph mark, and if a cop's around he'll get you. And, sure enough, any ti…

>'That's (supposedly) because a ticket for anything less than 10mph is simply not worth it for the cops.' Depends on your cops. I've witnessed tickets for 5 over (40 in a 45), 4 over (49 in a 45) and a stop, thankfully without a ticket for 1 over (31 in 30). I'm given to thinking of it as a lottery. Someone is getting pulled over, today me, tomorrow someone else. I'm just glad I haven't had a case of 'marijuana smell…

I think it more depends on your jurisdiction. When I'm driving somewhere new, I'll make sure I'm not going faster than average (even if that's below the speed limit). In places that I'm more familiar with, I'll do 9 over.

Re: Is Every Speed Limit Too Low?

#36

Post by tux1968 » Mon, Aug 04, 2014, 7:47 PM UTC

peatmoss wrote: post #32

tux1968 wrote: post #18

Earlier quoted context omitted.

There is conflicting evidence on the matter. A local (Vancouver) video[1] circulating here had some strong arguments that our speed limits are kept needlessly low. If you're interested in such things, it's a well done video and worth the 15 minutes it takes to watch. [1] http://www.vancitybuzz.com/2013/09/speed-does-not-kill-vanco...

Wrote my masters thesis in transportation planning on traffic calming. Peer review or it didn't happen. Not that peer review is perfect, but a viral video with an obvious agenda doesn't do it for me.

Heh, fair enough to be sure. However the video and the associated article that I linked do in fact reference multiple official studies.

Examples:

- http://www.fhwa.dot.gov/publications/research/safety/97084/9...

- http://www.th.gov.bc.ca/publications/eng_publications/speed_...

Re: Is Every Speed Limit Too Low?

#37

Post by streptomycin » Mon, Aug 04, 2014, 7:47 PM UTC

colanderman wrote: post #11

_archon_ wrote: post #4

I found myself disagreeing with the premise that highway speed limits don't influence people's driving speed. I may simply be part of the 15%, but consider the following anecdata: On I-90 in upstate NY, the "speed limit" is 65. I've gone by several state troopers at 70-75 without issue or confrontation. I don't go faster, not because traffic dictates, but I'm concerned about litigious policemen. To put it in Freakono…

It's not an arbitrary premise, it's studied: “Over the years, I’ve done many follow up studies after we raise or lower a speed limit,” Megge tells us. “Almost every time, the 85th percentile speed doesn’t change, or if it does, it’s by about 2 or 3 mph.”

And it's apparently controversial:

Just as Megge can point to the results on hundreds or thousands of roads which have become more safe or equally safe when the speed limit increased, other researchers looking at data sets of speed limit changes have come to the opposite conclusion and advise that raising speed limits comes with the price of thousands of roadway fatalities.

Although the article seems to support Megge and the studies he likes, it's not clear why (other than maybe that it makes for a more interesting blog post).

And honestly, I can't imagine I'm the only one who feels comfortable going 80 on a 65 MPH highway but not on a 55 MPH highway. I guess it is possible, but it seems hard to believe.

Re: Is Every Speed Limit Too Low?

#38

Post by cheald » Mon, Aug 04, 2014, 7:51 PM UTC

The data from Montana always struck me as interesting. It's not an awful lot of data presented in this report [1], but there was a substantial increase in traffic fatalities when Montana shifted from "Reasonable and Prudent" speed limits to posted-and-enforced speed limits.

I then found this report [2] which indicates that yearly fatalities are approximately double of what they were in the late 90s (and is now around the third highest fatality rate in the nation [3]). It's a good guess that traffic volume has gone up, but safety technology has improved as well, so there are a number of variables that have to be accounted for. The differences are certainly stark enough that it merits some consideration, though.

Nationwide, traffic fatality rates have been on a steady downward march over the last couple of decades [4], so Montana's tremendous leap in fatalities is absolutely anomalous. If I was debugging it, I'd start looking at what changed around that time. On the face, it certainly looks like posting and enforcing speed limits made the roads less safe, though.

[1] http://www.hwysafety.com/hwy_montana.htm

[2] http://www.mdt.mt.gov/publications/docs/brochures/safety/hsp...

[3] http://missoulian.com/news/local/report-montana-highway-deat...

[4] http://en.wikipedia.org/wiki/List_of_motor_vehicle_deaths_in...

Re: Is Every Speed Limit Too Low?

#39

Post by peatmoss » Mon, Aug 04, 2014, 7:52 PM UTC

tunesmith wrote: post #19

Raising the speed limit to the 85%/15% ratio isn't necessarily the safest way to handle the driving. If there's a road where more than 15% of drivers are going faster than the speed limit, one option is to raise the speed limit, but the other option is to change the road so people won't drive so fast on it.

Exactly. Ideally, speed limits are an expression of policy that reflect the normative values and desires of a jurisdiction. The best case would be for us to build roadways that reinforce those values.

Many roadways in the US were engineered under a set of assumptions that are incongruous with modern empirical understanding and with modern values. Wide roadways with big turning radii were thought to be safer. Turns out that encourages behaviors that are less safe for a multitude of roadway users. Similarly, there was a 20th century modernist notion that we should use the car for everything. Our bodies (everything from stress measured by cortisol levels, to obesity, to heart disease) object.

The 21st century task of planners is to figure out how to retrofit a system built around monoculture into a system that can accommodate a larger aggregate number of people. Part of that is traffic calming.

Re: Is Every Speed Limit Too Low?

#40

Post by colanderman » Mon, Aug 04, 2014, 7:56 PM UTC

thaumasiotes wrote: post #33

colanderman wrote: post #20

Earlier quoted context omitted.

I don't think you're disagreeing with the article's premise. Your "horrible drivers" can include people who either drive far too fast or far too slow, thus creating a speed differential. Lt. Megge's idea concedes that you can't get the fast drivers to slow down, but maybe you can get the slow drivers to speed up. (Aside, I agree 100% about more rigorous licensing. I spend 3 hrs on the highway each day; easily 80% of…

> driving slow in the left lane, passing on the right Is this two problems or one?

People who drive slow in the left lane are a problem, people who pass on the right are also a problem. Both these problems can exist independently. (Frustrated drivers don't have to pass on the right; on three-lane highways, people sometimes pass in the rightmost lane when the leftmost lane is free.)