Is Every Speed Limit Too Low? • Hacker News Board

Re: Is Every Speed Limit Too Low?

#91

Post by peatmoss » Mon, Aug 04, 2014, 9:17 PM UTC

cheald wrote: post #47

peatmoss wrote: post #43

Earlier quoted context omitted.

I've always loved this example. I lived in MT pre, during, and after this experiment. We went from: - 65 Mph - "Reasonable and prudent" daytime speed - 75 Mph daytime speed During the reasonable and prudent period, I think many people still had an internal model of 65 Mph. Certainly many people did drive faster. In my younger days, friends and I would find straight, empty sections of highway to flirt with death. But.…

Very interesting. How well do you think that 65 MPH internalized limit (during R&P) mapped to the 85/15% split as described in the original article? Do you have any other insights into other factors that might have contributed to the change in fatalities, or do you think it was just as simple as "people are driving 10 MPH faster on average", with correlated increases in fatality rates?

That's a really interesting question. My unscientific hunch is that there were two different populations of drivers on MT roads at the time. Lets call them the daredevils and the 65-ers.

I'd bet that among the 65-ers, it probably did map pretty well--or at least approximately as well as it did in states that retained a 65mph speed limit. You might have seen a few people creep up maybe instead of setting your cruise to 72 mph, in hopes of skirting a ticket, you set it to 75 because... round number?

The daredevils are pretty much by definition going to be exceeding the speed limit, but they could arguably be described as a different group, i.e. one that didn't internalize the 65 mph. A common narrative amongst Montanans of the time was that out-of-state types (most likely Californians, horror!) were coming to MT to treat our roads like a raceway. I'm sure that probably did happen to some extent, though who knows if it was actually a common occurrence.

Re: Is Every Speed Limit Too Low?

#92

Post by yason » Mon, Aug 04, 2014, 9:21 PM UTC

I think that the road design is a key factor in how fast people drive, not limits.

Wide lanes, one-way streets, and cleaned-up sides without obstacles encourage driving faster while narrower passes and trees/bushes on the side make you naturally slow down. On a road or street well designed you would drive at the limit even if you didn't know what the limit is because the limit is set to the "natural" speed of the road. This is what I believe is behind the sergeant's thinking.

On residential streets, a very narrow design would be the first thing to do in order to slow down automotive traffic and make the street more pleasant and safe for pedestrians. There are streets where it's nearly impossible to drive faster than 10 mph, so there are really no practical limits for speed governance in road design.

Conversely, on highways even astonishingly high speeds can be reasonably safe such as on German autobahns. Highways are mostly protected against the worst accidents such as head-on-head collisions. Things usually go wrong when someone disrupts the traffic flow by unattentive, blind lane changes. This is a completely different safety assessment than what's in effect on the streets of populated areas.

Re: Is Every Speed Limit Too Low?

#93

Post by tbrownaw » Mon, Aug 04, 2014, 9:23 PM UTC

clairity wrote: post #57

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…

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…

i'd even suggest that driving fast might cause you to be less distracted because of the higher severity of a crash

And because faster reaction times require you to stay more aware.

Unfortunately, trying to find where I heard about this just comes back with a bunch of stuff about risk tolerance w.r.t. financial investments.

Re: Is Every Speed Limit Too Low?

#94

Post by enf » Mon, Aug 04, 2014, 9:23 PM UTC

ameister14 wrote: post #71

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 think it's pretty interesting that you advocate for narrower roads and short setbacks because you belive that on roads like this people are less likely to speed. I don't know if people are less likely to speed on those roads; I think it is unlikely because growing up in a small town, people speed on backwoods roads all the time. Still, I'm not sure that this is the case. What I do know is that roads like that are l…

Most of the recent research on factors affecting vehicle speeds is summarized in http://onlinepubs.trb.org/onlinepubs/circulars/ec151.pdf

In it, Dimauita et al credit every foot of lane width with a 2 mph increase in vehicle speeds, and Wang et al credit each additional lane with a 6.5 mph increase.

Re: Is Every Speed Limit Too Low?

#95

Post by evjim » Mon, Aug 04, 2014, 9:27 PM UTC

I believe low speed limits give police officers a legal means to stereotype drivers and pull them over. Since everyone is now speeding, they can pick and choose who to pull over and have a legal reason. Young? sketchy car? minority?

Re: Is Every Speed Limit Too Low?

#96

Post by akgerber » Mon, Aug 04, 2014, 9:31 PM UTC

There is very little in this article about the interests of anyone not driving— crash severity is due to speed deltas, and pedestrians and cyclists are almost always moving much slower than automobiles. And a self-interested driver won't slow down to keep pedestrians safe, since pretty all of the consequences of a auto-pedestrian crash fall on the pedestrian.

Re: Is Every Speed Limit Too Low?

#97

Post by mturmon » Mon, Aug 04, 2014, 9:31 PM UTC

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…

There are also very high standards (strict regular inspections) regarding vehicle maintenance. US citizens would never put up with that.

Re: Is Every Speed Limit Too Low?

#98

Post by ajmurmann » Mon, Aug 04, 2014, 9:31 PM UTC

Having moved to the US from Germany, it always stroked me as particularly dangerous that it is common to overtake cars on the right and have slow cars and fast cars in any lane. The article mentions that different speeds are dangerous. I think enforcing cars sorting themselves properly into the right lane would make a huge difference in reducing accidents and allowing traffic to o faster. I wish law enforcement could focus on that instead of giving tickets to people who go 5mph/h faster than most other cars.

Re: Is Every Speed Limit Too Low?

#99

Post by Spooky23 » Mon, Aug 04, 2014, 9:35 PM UTC

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…

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.

Re: Is Every Speed Limit Too Low?

#100

Post by mbleigh » Mon, Aug 04, 2014, 9:35 PM UTC

I used to live in Atlanta where all of the major highways were capped at 55 around the city. The average highway speed was probably 75-80. If you drove the speed limit, you would be the most dangerous car on the road by forcing the flow of traffic to run around you.

Let's just focus on getting self-driving cars out the door as quickly as possible.