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A comment on Police Say Uber Is Likely Not at Fault for Self-Driving Car Fatality in Arizona. Parent comment

Re:Police Say Uber Is Likely Not at Fault for Self-Driving C... by in_cahoots on Monday March 19, 2018 @10:12PM (#16625439)
I don’t think that’s true at all (though I only have my own experience to go off of). I tend to use the speed limit as a point of reference, and then drive a little above it. Prior experience has told me that going the speed limit plus some percentage ‘feels’ safe. If there were no speed limit I’d actually have to pay more attention to the road and surrounding environment to determine what a safe speed is. Right now most people’s ‘survival instinct’ is basically speed limit + some delta in clear conditions. That delta may change from driver to driver, but in general everyone drives within 10-20% of the speed limit.

As a fun thought experiment, imagine what would happen if your residential speed limit were raised from 25mph to 70mph. People may not hit the 70mph limit, but I can almost guarantee that the average speed would increase significantly, perhaps even dangerously in some cases. I don’t have much faith in people’s ability to judge space and speed accurately, particularly when they aren’t used to doing so. And this includes myself.

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Re:Police Say Uber Is Likely Not at Fault for Self-Driving C... by franciscop on Tuesday March 20, 2018 @01:08AM (#16626188)
Ah but that is a whole different issue, the problem is that for the last few decades residential areas have been designed more and more like high-speed areas, and that had a larger impact on driver speed than the actual posted sign. I cannot seem to find the original articles but here are a couple of related ones:

- https://www.citylab.com/design/2015/11/some-20-mph-streets-a...

- http://plannersweb.com/2013/09/wide-neighborhood-street-part...

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Re:Police Say Uber Is Likely Not at Fault for Self-Driving C... by franciscop on Tuesday March 20, 2018 @01:18AM (#16626214)
A book on the topic quotes:

> "Note that the people drive the speed they feel comfortable with regardless of the posted speed limit if enforcement is not present"

- ref: https://books.google.co.jp/books?id=tF7uyw7feOMC&pg=SA13-PA1...

And a paper:

- "PEOPLE DRIVE THE SPEED THEY ARE COMFORTABLE WITH ON GRAVEL ROADS REGARDLESS OF SPEED LIMIT, K-STATE RESEARCHERS SAY"

- https://www.k-state.edu/media/newsreleases/april09/speedlimi...

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Re:Police Say Uber Is Likely Not at Fault for Self-Driving C... by URSpider94 on Tuesday March 20, 2018 @03:19AM (#16626545)
This is well-studied. It turns out that the 85th percentile speed (the speed where 85% of drivers are below that speed, 15% above) is nearly insensitive to speed limit. Road design is the biggest single determinant of travel speed. http://www.lsp.org/pdf/troopc85thSpeed.pdf
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Re:Police Say Uber Is Likely Not at Fault for Self-Driving C... by franciscop on Tuesday March 20, 2018 @04:32AM (#16626815)
Amazing insights:

> Won’t raising the speed limit cause people to drive faster and cause more crashes?

> The Federal Highway Administration studied nearly 200 roads in 22 states where speed limits were raised, lowered or left unchanged. Prior to the speed limit change, 55 percent of drivers exceeded the posted speed limits. After speed limits were raised or lowered as much as 20 mph, there was a slight change in speed, but generally less than 1 mph. There were no significant changes in crashes, although crashes tended to decrease where speed limits were increased to realistic levels. Also, there was little effect on speeds or crashes on intersecting or nearby roadways.

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Re:Police Say Uber Is Likely Not at Fault for Self-Driving C... by emj on Tuesday March 20, 2018 @07:52AM (#16627698)
This is for federal highways, traffic in a city should not go faster than 25mph in most shared spaces. Motorways is a different subject, but there should only be overpasses or resegined roads and traffic lights for such places.
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Re:Police Say Uber Is Likely Not at Fault for Self-Driving C... by helthanatos on Monday March 19, 2018 @10:50PM (#16625638)
I would like the speed limit on my interstates and highways to go up to 70(they're all straight. 55 is just the only speed limit around here). Driving at 65-70 feels safe in normal conditions. Driving above 70 feels a bit too fast. Speed limits should be more variable depending upon car size and braking power though. I hate having to fear that I might be pulled over for going a bit above the speed limit when there are so many more threats than just speed. I don't believe speed limits should be anything more than a suggestion with dangerous driving being the focus.
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Re:Police Say Uber Is Likely Not at Fault for Self-Driving C... by rootusrootus on Tuesday March 20, 2018 @12:58AM (#16626158)
I find this is extremely dependent on car. I've had cars that felt like you were about to die at 55 mph, and I've had cars that you couldn't tell you were going fast until you were really moving. For laughs, as my wife and I were driving home one afternoon earlier this year on a completely empty stretch of I-5 south of Portland, I casually accelerated up to about 110 and left it there for maybe a minute, then eased back down to normal speed as we came up into traffic. She never even looked up, didn't notice. But then again, we were in my brand new Camaro SS and I'm not positive it even got over 2000 RPM for that exercise, so I guess that's not a surprise.

So I guess I'm saying I agree. Speed limits are pretty arbitrary, there are a lot of things drivers do every day that are far more dangerous than merely speeding. Closure rate, unsafe passes, tailgating, cutting people off, etc.

/don't get me started about how people drive around you if you're towing a travel trailer, what the heck is it with people?

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Re:Police Say Uber Is Likely Not at Fault for Self-Driving C... by ryandrake on Monday March 19, 2018 @11:52PM (#16625922)
On most roads around where I live, if you are driving exactly the speed limit, you are a slow moving obstacle that is probably more of a danger due to the extreme speed differential with the other drivers who are 10-20 MPH over the limit. I’d hope self driving cars were programmed to deal safely within the bounds of reality. If there is nobody else on the road, sure drive the speed limit. If cars are whizzing past you on all sides you’re a hazard even if you’re obeying the law.
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