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Comment by GloamingNiblets | Hacker News Reader

I don't have any specific knowledge about Waymo's stack, but I can confidently say Waymo's reaction time is likely poorer than an attentive human. By the time sensor data makes it through the perception stack, prediction/planning stack, and back to the controls stack, you're likely looking at >500ms. Waymos have the advantage of consistency though (they never text and drive).

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> but I can confidently say [...] you're likely looking at >500ms

That sounds outrageous if true. Very strange to acknowledge you don't actually have any specific knowledge about this thing before doing a grand claim, not just "confidently", but also label it as such.

They've been publishing some stuff around latency (https://waymo.com/search?q=latency) but I'm not finding any concrete numbers, but I'd be very surprised if it was higher than the reaction time for a human, which seems to be around 400-600ms typically.

My experience is from another prominent AV company; I do not have Waymo insider knowledge.

> My experience is from another prominent AV company;

Better technology is one of the reasons that Waymo has an active autonomous ride service and no one else does.

Human reaction time is very difficult to average meaningfully. It ranges anywhere from a few hundred milliseconds on the low end to multiple seconds. The low end of that range consists of snap reactions by alert drivers, and the high end is common with distracted driving.

400-500ms is a fairly normal baseline for AV systems in my experience.

> Human reaction time is very difficult to average meaningfully

Indeed, my previously stated number was taken from here: https://news.mit.edu/2019/how-fast-humans-react-car-hazards-...

> MIT researchers have found an answer in a new study that shows humans need about 390 to 600 milliseconds to detect and react to road hazards, given only a single glance at the road — with younger drivers detecting hazards nearly twice as fast as older drivers.

But it'll be highly variable not just between individuals but state of mind, attentiveness and a whole lot of other things.

Even if we assume this to be true, waymos have the advantage of more sensors and less blind spots.

Unlike humans they can also sense what's behind the car or other spots not directly visible to a human. They can also measure distance very precisely due to lidars (and perhaps radars too?)

A human reacts to the red light when a car breaks, without that it will take you way more time due to stereo vision to realize that a car ahead was getting closer to you.

And I am pretty sure when the car detects certain obstacles fast approaching at certain distances, or if a car ahesd of you stopped suddenly or deer jumped or w/e it breaks directly it doesn't need neural networks processing those are probably low level failsafes that are very fast to compute and definitely faster than what a human could react to

What gives you that confidence?

You're quite wrong. It tends to be more like 100–200 ms, which is generally significantly faster than a human's reaction.

People have lots of fears about self-driving cars, but their reaction time shouldn't be on the list.

The better part of a decade as a SWE at another AV company. In practice the latency is a not a concern, I was just sharing some trivia.

Beyond the questions about human braking, this seems worse than the dedicated AEB systems many vehicles are using now. Do they really use the full stack for this case instead of a faster collision avoidance path? I remember some of their people talking about concurrency back in the DARPA Grand Challenge days and it seems like this would be a high priority for anyone working on a system like this.

Humans can provide a simple, pre-planned reaction to an expected event (e.g. "click when the reaction test shows a signal") within typically 250-300ms, but 500ms from vision to physically executed action for an unexpected event seems pretty optimistic for a human driver.

> I don't have any specific knowledge about Waymo's stack, but I can confidently say Waymo's reaction time is likely poorer than an attentive human.

Wait, so basically, "I don't know anything about this subject, but I'm confident regardless"?

Waymo "sees" further - including behind cars - and has persistent 360-degree awareness, wheres humans have to settle for time-division of the fovea and are limited to line-of-sight from driver's seat. Humans only have an advantage if the event is visible from the cabin, and they were already looking at it (i.e. it's in front of them) for every other scenario, Waymo has better perception + reaction times. "They just came out of nowhere" happens less for Waymo vehicles with their current sensor suite.

It's actually a really interesting topic to think about. Depending on the situation, there might be some indecision in a human driver that slows the process down. Whereas the Waymo probably has a decisive answer to whatever problem is facing it.

I don't really know the answers for sure here, but there's probably a gray area where humans struggle more than the Waymo.

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