Comment by birken | Hacker News Reader

Comment by birken | Hacker News Reader

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There are a few twitter accounts I follow who post some egregious infractions throughout SF. There have been some wins [1], but unfortunately I see the same types of violations by commercial vehicles posted over and over again and I think those drivers just don't care (and as far as I can tell they face little to no enforcement).

And for those on the high horse about cyclists breaking laws, just remember that nearly 100% of drivers break the law every time they drive --- speeding. Drivers think that going 30mph in a 25mph zone or 40mph in a 35mph zone isn't a big deal, but those small differences in speed mean a lot to people outside of vehicles if they get hit [2].

Also I haven't seen any data that shows that the most common cyclist infraction that everybody complains about, yielding at stop signs, actually is more dangerous. Yet it is very easy to show that speeding by vehicles is incredibly dangerous and costs many lives every year.

1: http://www.sfexaminer.com/uber-drivers-sf-receive-cyclist-sa...

2: http://nacto.org/docs/usdg/relationship_between_speed_risk_f...

Speed limits are decided under the assumption that people will exceed them under normal driving conditions.

In other words, speed limits are usually intentionally too slow. It would be insane to follow them in many situations.

"Speed limits are decided under the assumption that people will exceed them under normal driving conditions."

If true, this seems silly. So I'd love to know if you have specific information about the decision process, or whether this is just an assertion/feeling.

I think the idea being referred to is the 85th percentile speed. Here's a news article that talks about it: http://articles.latimes.com/2005/mar/09/autos/hy-wheels9

The way I heard it is that the limits are designed to be appropriate for night and/or wet driving conditions.

As a regular visitor to the US I follow the posted limits precisely. I have no intention of testing the varying law enforcement tolerances or discovering the possible complications for my immigration welcome the unpleasant way. As for the people leaning on the horn behind me, I've no sympathy at all: as far as I'm concerned, they're your rules, I'm just respecting them. As I do in every other country.

Wtf? Is this a US phenomenon?

In Australia people do stick to limits, more or less. At least, speeders are judged by other drivers fairly harshly.

Yeah, even after nearly two decades of driving and being aware that drivers in the US routinely exceed the speed limit I'm still a bit surprised by it.

Maybe it's because Australians get ticketed more for it, or are more likely to get ticketed for it. Back when I was living in one of the capitals (Adelaide) I recall there being quite a few fixed location speed cameras, red light cameras, and combined speed and red light cameras, plus regular mobile cameras on the arterial routes and often on the secondary routes.

Back when I used to expose myself to free-to-air TV I also remember there being regular advertising campaigns about how driving even 5k/hr faster increases stopping distance significantly. The required stopping distance on dry road at 40k/hr is 26 meters[1] and at 50k/hr is 35 meters.

Maybe we care about each other just a tad more. I don't know.

1. http://www.tmr.qld.gov.au/Safety/Driver-guide/Speeding/Stopp...

Yeah, in the US, it's pretty much acceptable to go 5 or 10 mph over the limit on any non-residential road. Cops generally don't ticket unless you are going 10+ mph over.

That's fascinating. In Holland we use a similar rule of thumb, but in Km/h, which is significantly less of a speed increase. Fascinating how the choice of unit of measurement affects behavior like this.

Going 8-20 Km/h too fast (the US equivalent) would definitely not be okay here. It happens, but if the police notices you're likely to get a ticket.

As an American, I have certainly internalized a safe +10% mph heuristic when it comes to speed limits.

My US driver's ed specifically instructed (unofficially) that, if the posted limit is over 40mph, feel free to go as much as 10mph over if it matches traffic conditions.

I follow them all the time. You are certainly capable of doing so, but you choose to endanger everyone else

Actually, the data suggests that humans naturally choose safe speeds without posted limits, and usually higher than what posted limits would have been. http://archive.etsc.eu/documents/copy_of_Speed%20Fact%20Shee...

Everyone I've met who drives under the speed limit is a bad driver who doesn't understand traffic dynamics enough to understand when going faster is more expedient and matches traffic patterns. By going too slow, you actually cause a hazard by forcing people to pass you.

This study is about highways only - doesn't involve city streets with pedestrians involved.

By going too fast you'd kill somebody especially in dense European cities.

Most city streets are at or below 35mph, where the +10mph heuristic does not apply.

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