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Comment by 2b3o4o | Hacker News Reader

According to the article the car was traveling at 17 miles an hour before it began braking. Presumably this was in a 25 mph school zone, so it seems the Waymo was already doing exactly what you describe - slowing down preemptively.

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This is close to a particular peeve I have. Occasionally I see signs on the street that say "Slow Down". I'm not talking about the electronic ones connected to radar detectors. Just metal and paint.

Here's my problem. If you follow the instructions on the sign, it still says to slow down. There's no threshold for slow enough. No matter how slow you're going, the sign says "Slow Down". So once you become ensnared in the visual cone of this sign, you'll be forced to sit stationary for all eternity.

But maybe there's a loop-hole. It doesn't say how fast you must decelerate. So if you come into the zone going fast enough, and decelerate slowly enough, you can make it past the sign with some remaining non-zero momentum.

You know, I've never been diagnosed on the spectrum, but I have some of the tendencies. lol.

Think of it like they're saying "my children play on this street and my neighbors walk here. Please think about that when you decide how fast to go here."

Obviously a static sign is not aware of your current state, so it's message can only be interpreted as relevant to your likely state... i.e. the posted speed limit.

If you should slow down relative to the posted speed limit why not change the speed limit to reflect that directly?

Usually the reason is the "slow down" portion is very small, and it's confusing to shift down the actual speed limit for a 200 foot stretch of road then increase it again.

Except we do that all the time in school zones... normally 35+, but from 7am-9am and again from 2pm-4pm the limit drops to 25mph (which is still to fast if the kids are actually crossing the street or walking alongside en masse).

FWIW, it seems less confusing to me than longer speed limits, but with "Slow Down".

There are signs for that. Advisory speeds that don't change the actual limit. https://wisconsindot.gov/PublishingImages/doing-bus/local-go...

Much better to be specific than a vague "slow down". There's a road near me with two tight turns a couple blocks apart. One advises 25mph and the other advises 10mph.

Think of the sign as a flag, not an instruction.

A lot of clickbait headlines have the same problem. "You're using too much washing powder!"

Everyone's replying to you as if you truly don't understand the sign's intention but I'm sure you do. It's just annoying to be doing everything right and the signs and headlines are still telling you you're wrong.

There was a driving safety safety ad campaign here: "Drive to the conditions. If they change, reduce your speed." You can imagine how slow we'd all be going if the weather kept changing.

We might have OCPD.

Yes. You have understood precisely the spirit in which I intended it.

In advertising: "Treat yourself. You deserve it!"

Me: What if someone who didn't deserve it heard this message. How can you possibly know what I deserve? Do all people deserve to treat themselves? Is the notion of deserving or treating really so vacuous?

Normies: jfc

There's a mental health awareness campaign going on around here at the moment with all the generic messages like that. "You're doing great" is completely devalued by the sign giving the same message to everyone, and the best one says something like "Don't push yourself too hard. If you want to rest, rest." Wondering if I can tell my boss the sign told me it's okay not to get any work done.

Humans are supposed to deal with this kind of ambiguity. Actually, that's one of our nicest abilities.

I hate when people pretend to be smarter than everyone else by pointing this kind of utterance and insisting that someone, somehow, will parse those statements in the most literal and stupid manner.

Then there are the ignorant misanthropes that can't waste a chance to repeat their reductionist speculations about human cognition. Just like the idiot Elon Musk that wasted billions in irrecoverably fucked self-driving system based on computer-version because he underestimated the human visual cortex.

Fucking annoying midwits.

Sorry I made you mad. I wasn't trying to seem smarter than everyone. Maybe dumber.

A very kind response to such a grating lack of self-awareness.

You learn how to put those signs into context during your driving lessons, and fail your test if you don't apply that correctly.

I apologize if I gave the impression that I did not understand how to put them into context. Although I don't think my driving lessons ever mentioned it.

This is idle XKCD-style musing.

My driving test was so thorough that I had to parallel park between two entirely fictional cars. There was certainly no consideration of eccentric signage.

25 mph is an upper limit, not a minimum.

A 25mph school zone? That seems fast. 15mph would be more the norm, which is in line with the 17mph the car believed itself to be traveling.

FYI, unless you are a commerical truck, a cop, or a racer, your speedometer will read slightly fast, sometimes as much as 5 to 10%. This is normal practice for cars as it limits manufacturer liability. You can check this using independant gps, ie not an in-dash unit. (Just imagine the court cases if a speedo read slower than the actual speed and you can understand why this started.)

Also, a different wheel diameter than the speedometer was calibrated with and you will have a larger difference between actual velocity and speedometer reading. The odometer will also not record actual distance traveled.

It depends. I had a honda motorcycle where the speedo was 10ish % fast (not unussual on bikes due to tire shape) but the odo was accutrate. Same sensor, but the computer just counted wheel rotations slightly differently for each use.

Virtually all speedos read fast. The federal standards have a fairly high margin for being allowed to read high, and a zero margin for reading low. Thus speedos are more or less universally calibrated to read at least 5% high.

I mostly see 25 mph for school zones, though I'm in NC. Checking California, it sounds like 25 is standard there as well.[0] Some will drop to 15, but 25 is the norm as far as I can find.

[0] https://www.dmv.ca.gov/portal/handbook/california-driver-han...

I've lived all over California and I agree that 25mph is the norm here.

Edit: However, elsewhere in the thread someone linked this Streetview image that shoes that this particular school zone is 15mph: https://maps.app.goo.gl/7PcB2zskuKyYB56W8?g_st=ac

25 mph is typical non-school-zone residential around here, with school zones always slower.

In Encinitas, California, that sign would have no more than 20 MPH. In adjacent Carlsbad, I believe 25 is normal.

It does seem fast to me -- school zones are 20 mph in Seattle, at least when children are present. But Google suggests 25 is the norm in Santa Monica, where the incident occurred.

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