Wait, how does that work? Every person in your city needs to know the exact calendar of that school?

In NSW (Australia) that's exactly how it works. And it includes 'pupil-free' days where there are no students present. My old school even had a pedestrian bridge and barriers so that it wasn't even possible to get to the road.

It's so silly, when the obvious solution is to make school zones 40km/hr (25mi/hr) at all times, or to fix the road design. Typical speeds here are 60km/hr (40mi/hr), so anyone making the argument that it would 'slow traffic' is being dramatic.

(There is one exception that I know of - our east coast highway used to go near a school, which forced a change from 110km/hr (70mi/hr) to 40km/hr. In this case I will concede the speed is not the issue, the highway location is the issue)

> (There is one exception that I know of - our east coast highway used to go near a school, which forced a change from 110km/hr (70mi/hr) to 40km/hr. In this case I will concede the speed is not the issue, the highway location is the issue)

They couldn't just put up a fence?

A fence and a pedestrian bridge would do the job. Long term I think that highway is going to bypass all the towns

In Victoria there is usually (not certain if it's always) a changeable sign and flashing lights if it's reduced to 40

Yes, that's how it works in Alberta. It's particularly confusing because not all schools have the same academic calendar (e.g., most schools have a summer break, but a few have summer classes).

Unlike the sibling comment, there are no lights or indications of when school is in session. You must memorize the academic calendar of every school you drive past in order to know the speed limit. In practice, this means being conservative and driving more slowly in unfamiliar areas.

This is another example of something where, at least if you want to get all the way to completely correct operation, it's easier for an driverless car than a human. A person can't memorize the schedules of every school district they might pass, but an automated system potentially could. Of course something like Google Maps could solve this too, for both humans and Waymo.

Is it really such an imposition to simply drive at the posted limit at all times when passing a school? It only takes a few seconds even if you slow to a crawl.

In the UK we have a sign saying something like "20MPH WHEN LIGHTS ARE FLASHING". During term time when pupils are entering or leaving the school (say between 8am and 9:30am, around lunchtime, and from around 3pm to 4:30pm) someone at the school switches the lights on. Usually it's one of the "lollipop men" who stand at crossing points that are not otherwise marked, and hold out a sign to stop traffic to let children cross, but often it's just programmed into some timer somewhere.

It's pretty simple.

You don't need clever software or self-driving cars, you just need to lift your right foot a little near schools.

https://maps.app.goo.gl/34QgN2KTQmGML2Ae8

Here is an example of one that just lights up with a 20mph limit when it's needed, from near where I grew up. Pretty high-tech for a remote part of the world, eh?

Ok, I get it. Here we just have 30kph limit with speed bumps at all times.

You are not penalized for failing to go over 35 on non-school-days. School zones are sufficiently small that the time penalty for complying on a summer weekday isn't that much of an inconvenience.

Where I am, the school zone signs fold up; during the off season, they're folded and say things like drive nice; during the on season, they are unfolded and present the limit.

the sign says the hours for the reduced speed limit or, more commonly in my experience, has a light that activates during school hours.

The light and often even the sign itself are typically considered informational aids rather than strict determinants of legality. The driver is expected to comply with all the nitpicky details of the law regardless of whether the bulb is burned out or the school schedule changes.

Needless to say, most people regularly violate some kind of traffic law, we just don't enforce it.

of course. i'm confident slowing down near a school is pretty intuitive for the vast majority of drivers, though.

Sure, but the context here is a discussion about how a computer can know all of these "intuitive" rules humans follow.

The answer is encoded in the map data in this case, but it's an interesting category of problems for autonomous vehicles.

Have you had the experience of riding in a Waymo making a left hand turn against incoming traffic -- and how it handles the eventual yellow light?

I was very impressed about the decision making in this situation. Seems very intuitive (at least superficially).

it wasn’t at first but I suspect they received a ton of feedback and fixed it.

in my estimation the robo driver has reached a median-human level of driving skill. it still doesn’t quite know how to balance the weight of the car through turns and it sometimes gets fussy with holding lanes at night but otherwise it mimics human behaviors pretty well except where they’re illegal like rolling through the first stop at a stop sign.

Now I’m imagining the Waymo Driver calling out to Gemini to determine "school hours" by looking it up on the Internet, and wondering about the nature of life.

In the area I live, the wording is frequently "when children present" so you don't need to know school schedule.

Present means "present in the school." It's not always observable while driving by if you need to obey the reduced limit or not. California does it and I find it absurd.

Many other states setup a flashing yellow light and program the light with the school schedule. Then the limit only applies "when light is flashing." Far more sensible.

This is the one most familiar to me. Usually the signs have flashing orange lights to indicate when they're active, but sometimes not. You generally know roughly when the kids are in school (maybe look at the school?), and follow what other drivers are doing. Things like this are why I think fully autonomous driving basically requires AGI.

You can always just slow down for 30 seconds if you're not sure.

They should just always observe the lower speed limit.

The difference is usually 5 or maybe 10 mph.

Which over the distance of a school zone is nothing.

It can be dangerous though. In my area we have roads with speed limits of 45 that drop to 25 "when children are present". My EV always assumes children are present as it has no real way to determine if they are. Driving 25 in a 45 is dangerous for many reasons.

Neither do you, the lower speed limit applies when children are present inside the school.

A building that looks the same with it without children inside of it.

It can just read the sign surely? My ancient Tesla S can read simple speed limit signs and in France distinguishes between those that apply to it and those that apply only to lorries because of the notice below the speed limit sign.

Then it really would be as simple as looking up the calendar or simply erring on the safe side that all weekdays are schooldays.

Waymo only operates on fully mapped roads anyway so I think that Waymo could be reasonably expected to include such abilities.

Aren’t they supposed to read signs? Otherwise they’d also ignore the overhead speed limits on the highway for traffic jams / air quality adjustments during the day.

GP is saying that reading the sign is insufficient to determine whether it is a school day. You have to either guess based on the presence of students or busses, the lights being on, etc., or you have to source the school calendar somehow.

I don't know how it is there, but here those signs near schools light up and blink during school hours (really can't miss it). And for signs that do not, I think school days are pretty fixed, shouldn't be difficult to program... and a default of just slowing down would be just fine too.

This sign doesn’t have a flashing light.

Are school days ever Sundays? If not, perhaps all drivers just treat every non-Sunday as school day. If so, they probably just slow every day.