Comment by grumbel

3 days ago

I am a little worried that this is still a problem after 20 years. Don't they have simulators to test every weird and unexpected road condition offline? And flooded roads aren't exactly an unusual event to begin with.

In ATL this happens often enough that it's not a shock when it happens, we have lots of drainage problems here. I agree that I would have assumed Waymo had tested in events like this, but clearly not. So what I can say is running in ATL is a great test case for these events, and also the people who live here don't do a better job than Waymo did. There were dozens of people who ruined their cars yesterday trying to drive through deep water.

  • There is a pretty big difference between a citizen driving their car into danger, and a service provider driving their car into danger with you in it.

    You wouldn't accept that from a taxi driver either. Pausing the service is the right move.

    • I completely agree pausing service is the right move. I'm not defending Waymo. More laughing at my fellow ATLiens.

  • We had a story in the news this week about a Cybertruck driver who thought his Elonmobile was a boat because it has "wade mode" and deliberately drove into a lake! Humans are very stupid when it comes to driving through standing water!

    • To be fair if you take Elon Musk at his word the Cybertruck is supposed to have hermetically sealed powertrain components and be capable of exactly this.

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  • As much as one could expect waymo to train on it, one could also expect a functioning city to not have flooded streets

    • Why?

      Functioning cities often shutdown for a day here or there for weather. I live in a northern city where we laugh at southern cities for shutting down for 1 inch of snow - but it is the right thing for them because it doesn't happen enough to be worth dealing with. If my city shutdown for 6 inches of snow we would be shutdown unacceptably often so we instead have higher taxes to pay for all the infrastructure needed to deal with snow (though honestly this isn't much $ in the total budget).

      Which is to say cities need to figure out what is the best use of their efforts/money. It is wrong to fault Atlanta for not dealing with this. If you live there you as a voter should learn all the pros and cons (I suspect there are some unexpected environmental ones) and consider if you should vote for a change or just deal with it. The rest of us won't don't live there though should keep our fingers out of their local issues.

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    • Streets flood sometimes. Shit happens.

      And when it does happen: A Waymo should not fucking drive through it.

      I remember once when the mall in my hometown flooded. It was at the top of a hill.

      IIRC: The top of that hill received something like 6" of rain in less than 15 minutes, in a very "Fuck you in particular" sort of way.

      The vaguely-greater surrounding area was fine. It was a very localized event.

      They were not prepared for this. It was a mess.

      And gosh: The streets near there flooded, too. The drainage systems were simply not up to the task.

      It had never happened before, and it has never happened since, but: Quite clearly, it happens.

      (I don't understand your deflection here, at all. If your main point is that "If cities were designed better, then the deficiencies of autonomous cars wouldn't be a big deal for those autonomous cars at all" then I might reasonably conclude that you're just not particularly observant of the world.)

      ---

      edit: People also screw things up. We (people) drive through flooded roads sometimes -- we even do it on purpose from time to time, even though the guidance is to avoid it.

      Some other times, we get surprised by flooded roads. Especially at night, they can be hard to detect. We screw things up. We take risks. Sometimes, those risks even work out OK.

      But back in context: Waymo. Waymo is an autonomous taxi cab. It works on regular public streets, and on a long-enough timeline: Some of those streets will be flooded.

      I probably never want my taxi driver to try to ferry me through a flooded roadway, whether it has a human brain or a computer brain calling the shots.

      (I did get to spend a week getting ferried ~daily through flooded roads in a Jeep once in an unrelated flood, but by a high-ranking deputy Sheriff was (who would not become confused by a power outage[1]), and this Jeep was a proper cop car with the lights and the logos. We had some mutual problems that needed solved that involved public safety, and both of us were being paid to solve those problems. That worked fine, I knew what I was getting into before we set forth, and we'd have had extraordinary support if anything went very wrong.)

      [1]: https://news.ycombinator.com/item?id=46342412

    • That's like saying one could expect New Orleans not to flood during hurricanes.

      There are problems.

      There is money you can throw at those problems.

      And there are some problems that are rare & low impact enough that it's not worth throwing money at them.

      See also: keeping snowplows in Atlanta.

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    • On one hand, sure, but on the other, Earth doesn't care what we expect. And humans don't build rationally most of the time. Most cities are hundreds or thousands of years old.

    • It would be a massive waste of resources to build out every city with a drainage system capable of handling any amount of rain. Houston had ~30 inches of water dumped on it during a somewhat recent hurricane, designing and building infrastructure for that level of storm is not realistic. I’m not familiar with storm sewer capacity design, but I’m confident they aren’t designed to flawlessly handle a 1 in 500 or 1 in 1000 year event.

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    • >one could also expect a functioning city to not have flooded streets

      In some cities, certain streets are designed to flood during heavy rain, and are an integral part of routing the water away from neighborhoods and businesses, and into the drainage systems.

  • SV is the most cloistered place I've ever seen. I'm comfortable assuming that nobody in any position of power at Waymo ever thought to themselves "gee maybe the weather is different in this new city we're deploying to, perhaps we should test that"

    • As a former engineer and manager at Waymo I can say with the confidence and sincerity of firsthand experience that this is not the case. People at all levels of the company think deeply about how different locations have present different challenges, including different weather.

      Also it's not like we never have flooded roads here in the valley.

      Whatever is going on, I'm confident it's not a result of straightforward parochialism in the way that you say you're comfortable assuming.

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    • I worked in the field, not at Waymo. Everyone in the business is acutely aware of weather, along with hundreds of other factors, many much less obvious.

      The engineers whose expertise you assume away are actually debating corner cases like the one we saw of someone carrying a bicycle on their skateboard.

      In fact the companies run test campaigns in shitty weather all over the country on purpose, at great expense.

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    • There's a long tail of unpredictable events in the AV industry that you end up seeing, especially since the cars in aggregate end up driving more than one could over a lifetime.

      At a previous employer, we've seen anything from cars getting mooned, a SUV slowly driving past the AV, the rear window roll down, and someone poke their head out and start throwing dollar bills at the AV, a convention of people dressed up in animal costumes, the "Miami left," and so on.

      So it's much less of "maybe we should test that" and more of "we don't know what we don't know, so let's gather some data." In practice, the cars have lidar so they won't crash into solid objects that aren't recognized, they just end up getting stuck in embarrassing situations like these.

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    • This seems silly -- they roll the service out to individual cities in different regions, one at a time. Why do you think they do that? I'm pretty sure this is exactly that testing that you're referring to.

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They can simulate "driving out of a raging fire" but not a flooded street? This seems like an admission that the fancy "world model simulation" doesn't actually mean much

https://waymo.com/blog/2026/02/the-waymo-world-model-a-new-f...

  • IMO there is a lot of daylight between “is not perfectly capable of simulating all situations and always used perfectly to the full capabilities of the system” and “doesn’t mean much”.

  • No simulation is perfect, so ideally you have a feedback look constantly looking at new real-world data as it comes in and finding where the simulation has errors, and updating the simulation to improve the correlation between the simulation and the real world over time.

    My guess is they did have flooded street sims but the correlation was much lower than expected, or the details of the situation being simulated (lighting, building locations, how dirty the water is, ...) were sufficiently different from the situation that was encountered that the sim based training didn't generalize to the new context.

"Don't they have simulators to test every weird and unexpected road condition offline? "

I remember when this was brought up in a Cruise (RIP) crash. The situation was that another human driver had hit and run a pedestrian who had been flung across the street and under a Cruise self-driving car. The cars were getting complaints for making too many emergency stops in the middle of the street, so it dutifully dragged the lady in the under-carriage a couple of more feet to get off to the side of the road.

Suffice to say that that had not coming up in simulation.

P.S: Lady survived but the Human hit and run driver is still at large. No one wrote about them or cared.

It can just mean that nobody though about flooded streets, what's way more reasonable than it seems because of the birthday paradox.

But that also means they need a long time to adapt to a new situation. That may be very bad depending on how fine grained a situation is defined, or it may mean nothing and in a few months they'll be back without problems.

Can Waymo cars even sense or detect flooded roadways? That is when it sees images of water covering the road, is it smart enough to know the car might get pushed into the raging waters?

This is one of the reasons why I switched to Apple Maps years ago. Google Maps kept giving directions to small backroads that I knew were prone to flooding. I noticed it when Google announced they were changing the algorithm to save people gas or something.

Yeah, it makes me wonder about their planned rollout to more of Southern California, where flooded roads aren't uncommon, especially in some of the valleys.

Just because there are real world failures doesn't mean they didn't do simulations. It could just mean the simulation didn't account for something different in the real world.

The website for software engineers is assuming that a production failure means nobody did any testing before prod...

  • So what you're saying is that something far worse happened here. They did test for flooded streets but some slight difference caused the model to fail in real life.

    To be fair, there will always be something that fails. So the more important question is probably the frequency and severity of those failures.

To me standing water sounds like obvious thing to include in testing. And maybe even design some reasonable technical solution like sensors near say wheels.

Areas with water should not be that uncommon that vehicles would never accidentally enter them. So seems like pools of say 10cm deep water should be included in testing.

  • A merely wet road (1mm of water) and one with 10cm can be hard to distinguish. If you avoid the former, you can't operate in rain at all.

The fact that they aren't a usual event is probably exactly the challenge here.

  • It may not be usual in Atlanta itself, but living on the Southeastern coast within a mile or two of the water, for 30+ years, it’s a surprisingly common occurrence. I’ve got old photos around of kayaking through downtown Charleston during college, for instance, where the street flooding is not only usual but a many times per season occurrence. Lots of seaside areas have the same issue.

    •     > it’s a surprisingly common occurrence
      

      That is wild. What happens to all of the flooded property? Do they tear-down and rebuild everything after every major flood? Or massive rennovations? It cannot believe this is truly possible as flood insurance would become impossible expensive.

  • I’ve lived in a place where it flooded every year or two. It floods regularly where I live now too.

    Locals know which roads to avoid and not to drive into a flood.

testing cannot prove the absence of bugs. It can only prove that you didn't find any, which is a completely different thing

It’s been clear for a while to anyone without money riding on this that the relatively “easy” part fooled a lot of people into assuming that the last push to full self driving wouldn’t be radically greater challenge.