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Comment by lelanthran | Hacker News Reader

> “idiot in front of me slammed on their brakes at the last second while I was scanning left or right”; the system kicked in and legitimately prevented an accident.

How many accidents have you had of that type in the past, say, 300000km of driving?

Because you say it legitimately prevented an accident, but this is a routine thing that happens (drivers slam on brakes at the last second) and if you aren't routinely driving into the rear of cars who brake at the last minute, then ... no, the accident wouldn't have happened anyway.

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I haven't looked into it, but I'm sure studies have and/or are being done on this. I wonder if the rate of incidence of rear-end type accidents has changed noticeably with these systems becoming standard. A quick Google suggestions around 30% of accidents are rear-end, accounting for something like 1.75 million accidents annually. What % reduction in these would make it make sense to "require" this? I'm not sure, I personally can't stand currently implementations, but it does seem like an easy thing to target for reduction.

As an aside, trying to quickly search for these sorts of statistics leads to an awful lot of law firm websites.

> A quick Google suggestions around 30% of accidents are rear-end, accounting for something like 1.75 million accidents annually.

But that number is not relevant. What is relevant is the ratio of humans avoiding these accidents to humans not avoiding these accidents.

Like I said, having to avoid the car in front which braked hard is routine. It happens all the time. It's why the blame and culpability for a rear-end accident is always on the rear driver by default - safe driving distance and all that.

Which is why I phrased my question to the GP the way I did - if he managed to go 300000km without rear-ending someone even though unpredictable braking happens so routinely ...

> What % reduction in these would make it make sense to "require" this?

I doubt there'll be a decrease, if any. A better system that beeps if a safe minimum following distance is not adhered to will almost certainly prevent more accidents than auto-braking, because the auto-braking system will sometimes get it wrong and cause the jackass tailing you to rear-end you.

An alert won't cause any accidents.

I'm not entirely sure I follow your argument. 1.75MM rear endings occur yearly. Decreasing that number does seem relevant. Could / do these auto-brakes decrease that number? You seem to think no, per your second quote comment - I'm not sure, I haven't done any further research to see if there's a trend. I wouldn't be surprised in either direction, honestly. The ratio of accidents to "near miss" is probably hundred(s?) to one, but could this make it more? I don't know. Fwiw - I'm anti-auto-brake as a rule, but I'm just curious if the data would be in their favor or not.

I don't have an auto-brake feature, only ridden with people who do. I believe that most of them do have some sort of warn prior to brake - but to your point, there are so many situations where this could falsely trigger that it would likely end up being tuned out, at least as I imagine it. Actually, my truck has one of the "warning" things, and I ultimately turned it off for this reason. The number of "immediate danger" warnings that would flash when I was driving, e.g. alone on a country road at night, made it not worthwhile to me. I can imagine an auto-brake would be even worse that way though, lol.

Anecdotally one (only been in one accident ever), but regrettably in that case I was the idiot braking at the last moment, and the driver behind me was distracted and rear ended me. Gave me a concussion that would have been nice to avoid.

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