Nah, I'm jumping straight to this conclusion: if you hit something in front of you that didn't leap out in front of you at the last second, you fucked up. The object that you hit was erratically slowing and speeding up? You should have left more room to allow for the unpredictability. It was raining, can't see, the roads are slick? Leave more room in front of you.

Yes, I way too often don't do that, either. But if there's something in the road ahead of me, and I hit it? Man, there are few scenarios where I can claim that there was nothing I could do. And in the case of a full-sized vehicle in front of me, I don't care how erratically it's driving, don't run into the back of it.

The only time it can be not your fault is if the slow moving car switches lanes in front of you before there is time to stop.

His actual statement was, "if you rear-end someone that you are following, it is your fault..."

If someone abruptly pulls in front of you, you weren't following them.

Related to this is glare from the sun or artificial sources. I lived in a small city with antique-style globe lamps on Main Street. The veiling glare made pedestrians invisible, and even if you knew about the glare and watched for pedestrians, you would still be surprised when they became visible halfway across the street in front of you.

It's not causing accidents in these cases. The humans are.

So while your statement isn't wrong, it's also not always pragmatic in the real world.

Indeed - this is the 70mph is slower than 50mph thing I mention.

If not, then you already recognize the probability is less than 100%, so that has to be baked into your statement.

The only comments saying that are...yours. If your argument is so lacking that you need to argue in bad faith, perhaps it is best to not bother at all.

Or perhaps you are not aware of the proper following distance (and therefore, part of the problem about which you complain). Two car lengths (EDIT: seconds, not car lengths; oops) is the general advice.

>Two car lengths is the general advice.

No. It's speed, roadway, and car dependent. Two car lengths isn't even sufficient at 25mph let alone at 70mph.[1] Which all goes to show how poorly people tend to think about these things and quickly resort to overly simplified mental models.

[1] https://one.nhtsa.gov/nhtsa/Safety1nNum3ers/august2015/S1N_A...

Moreso that my post has a mistake: two second following distance, not car lengths. Brain fart on my part; apologies for causing you to have to find a URL. But as general rules go, that increases the distance as speed goes up. No, it doesn’t account for everything, but good enough for most circumstances.

Like most real-world engineering, there is a cost-benefit balance. Could we design an interstate highway system that allows everyone a 10 car buffer? Sure. Would we like how much it costs, the effects on the environment, etc.? Probably not.

As an aside, your comment seems to go against HN guidelines by taking the least charitable interpretation of the comment.

You might have forgotten the ultimate rule of road safety: Everything is a tradeoff. Safer is only sometimes better. Otherwise the speed limit would be 10mph, because it's quite a safe speed.

Roads like that are currently operating at bursting point. There are incidents and accidents every single day and constant police presence is required to unblock them. If you alleviate congestion, more people use the road. They just go back to bursting point. In other words, it's utterly insane.

Can you imagine if there were accidents on railways or in the air every day? Imagine the scandal if train operators were found to be unsafely squeezing more trains on to the line that it could handle. Roads are stressful, inefficient and shit. Enforcing a safe stopping distance and pricing journeys accordingly, like trains, is where we want to be.

I don't disagree about "pricing journeys accordingly," but there are many reasons why this is difficult in practice in the US. Going through those points is a bit of a digression from my main point. Namely, that there are pragmatic tradeoffs that have to be considered. I'm consistently taken aback by the amount of "simple" solutions people advocate on HN and sometimes I wonder if it's due to software developers constantly working with the abstract rather than the concrete.

You do not have to raise the average speed of travel very much to make up the theoretical loss due to increased spacing

Moral: support public transit.

I'm nearly certain that I'm alive today because I drove as defensively as something like a Waymo. One day as I was approaching an intersection where I had a green light, I saw a car approaching the same intersection from the cross street at a speed that they couldn't have possibly stopped for their red light.

I instinctively slowed down suddenly and that car, as I predicted , ran the red light at high speed and turned just a few yards in front of me.

If I had been more tired, hasty, or it had been darker out, I might not have seen it or reacted in time. A fully autonomous and defensive driving system wouldn't get tired or hasty, and lidar can see fine at night.

And yes, I might have gotten rear ended, but that's a far better outcome than getting t-boned by a car going 65mph.

If you had just been an average driver. Most people are terrible at defensive driving.

Mostly because people misunderstand what defensive driving means.

It doesn't mean "go slow". It means always maintain a safety margin between your vehicle and others, adjusted for speed, road conditions, and relative direction of travel.

Those are the kinds of objectives a self driving system can very reliably achieve, unlike a human.

Most human drivers I observe are taking huge chances every single day. I see them drive at speed around corners they can't see around fully, driving far too closely to cars front, using their phone etc. They get lucky but it's only a matter of time before they have accidents. The three incidents recorded here are simply due to three humans' luck running out.