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Comment by parkingrift | Hacker News Reader

Unfortunately, self driving cars drive in the real world. There are a great many roadways in the US where driving the speed limit is legitimately dangerous in one direction or another.

I live in New York and there is one such roadway I drive often. Palisades Interstate Parkway. The speed limit is 55 and there are no trucks allowed, but if you are driving 55 on this road you are in danger. You will get run off the road by everyone else traveling at a minimum of 65-70 with many of them 80+.

There may come a day where humans are completely out of the equation, but until that time I believe self driving cars are safer if they drive more like human drivers. That means keeping up with traffic and other human quirks.

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Agreed, and these roadways are all over the country. It's a pretty widely known fact that the safest speed is the natural flow of traffic, but municipalities all over the country are much more inclined to listen to the vocal minority over traffic engineers. Not a lot of "trust the science" going on there.

https://qz.com/969885/almost-every-speed-limit-is-too-low/

The solution to that is not that everybody gets to ignore speed limits and point to a QZ article as justification. The solution is not that Tesla unilaterally decides that 10% more is fine, everywhere, all of the time. The solution is what the advocate in your article proposes - make a conscious decision to raise the speed limit on certain roads, backed with suitable data.

That’s a lot of snark for such an obtuse comment. Obviously we should fix our laws, but in the meantime we shouldn’t imperil ourselves and everyone around us just to pacify the people who lobby their municipal governments for unsafe speed limits.

Next week’s argument: “all first gen self driving cars are going 70 where 55 is allowed, we need to keep this setting.”

Wait, so you're saying that people would crash into you if you drove the speed limit?

I'm a very calm driver and regularly drive at or sometimes below the speed limit if visibility or other factors don't allow higher speeds. People do slow down and I never felt in danger - granted, this is usually at around 40 km/h instead of the limit of 50 km/h, but I can't imagine people are so careless they'd "run you off the road" if you weren't speeding.

> Wait, so you're saying that people would crash into you if you drove the speed limit?

Yes. If you're driving significantly above or below the speed of traffic, you're likely to cause an accident. https://qz.com/969885/almost-every-speed-limit-is-too-low/

>Wait, so you're saying that people would crash into you if you drove the speed limit?

Maybe not literally crash into you, but that is certainly possible. People will swerve around you, ride your bumper, flash their high beams at you, honk, pull in front of you and hit the brakes, and other dangerous road rage type behavior. It is absolutely unsafe to drive the speed limit.

In general the safest thing to do is just to keep up with traffic.

That’s exactly what the driver in front of you and behind you use as justification for being above the limit: I had to go with the flow of traffic. A self-perpetuating force that forces everyone to be too fast.

Disagree. Traffic engineers study roadways and recommend speed limits based on safety and human behavior. And then cities and states ignore them and use speed limits to generate revenue.

>A self-perpetuating force that forces everyone to be too fast.

If it were actually too fast, most people wouldn't travel that speed. Have you ever noticed that traffic speed ebbs and flows with the road conditions or time of day? People will drive the speed they feel safe driving, and for most drivers it's (typically) much faster than the posted speed limit. And if the conditions are poor, it's much slower.

> Traffic engineers study roadways and recommend speed limits based on safety and human behavior.

This isn't really true: what usually happens is that they either go with a default or they do a study and set the limits at the 85th percentile. For a separated highway, that works fairly well but it often has bad results for mixed spaces: the people commuting through a neighborhood, for example, are trying to go as fast as possible but the people who live there are more concerned about safety, the impacts of those decisions on how they use their space (I grew up hearing that “nobody walks in California” which really meant “nobody wants to walk 3 miles further to use the few signaled crosswalks”), etc. A big problem here are the outliers: most of the risk comes from the top of the speed distribution — even if half of the drivers scrupulously follow the speed limit, the speeders are the ones who will influence people's safety perception of the road.

> And then cities and states ignore them and use speed limits to generate revenue.

I think for highways and other limited access roads they're often concerned with minimizing complaints much like the commentary we're seeing up and down these comments so they slap a small number on the sign knowing full well that traffic will ignore it and call it job well done.

People will swerve around you, ride your bumper, flash their high beams at you, honk, pull in front of you and hit the brakes, and other dangerous road rage type behavior.

I don't think the one being unsafe in this scenario is the one driving the speed limit!

Does it matter if the result of the behavior is that you are unsafe?

When you're driving significantly below the speed limit (or more accurately, below the average speed of the other drivers), it becomes impossible to maintain proper dostance behind you. Add to that the fact that people randomly drive in the left/middle lanes regardless of actually passing anyone on their right and you're forcing people to brake, make dangerous merges, etc.

I know nothing about your driving, but I find (anecdotally) that drivers who drive significantly slower than traffic are also ones who never look in their rear view mirrors.

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