That in itself can also be dangerous. There are in fact traffic laws in various places against driving too slow or otherwise impeding traffic flow because doing so can cause accidents.

You are always allowed to stop in an emergency. Or if your engine stops working for example ;)

You're supposed to turn on your blinkers and pull over ASAP. Stopping cold on a highway lane is a huge hazard.

And you can't use your warnings from the front (well you can but they'll be invisible).

So unless the self-driving vehicle has a routine to activate those on weird slowdown it may be very hard for the traffic coming behind to notice, further increasing the danger.

Tesla autopilot can overtake slow cars. You might have to swerve and block it. Certainly possible, as it is not aggressive, but it wouldn't be as straightforward to stop it as with regular traffic aware cruise control.

That's possible, but the article said that it changed lanes to the left while signaling to the right. That rules out having NoA enabled with "confirmationless" lane changes.

That would rule out autopilot entirely, wouldn't it? If true then this is just a case of someone falling asleep behind the wheel that could happen in any car. But with modern safety features like lane departure avoidance and automatic emergency braking. Tesla's active safety features can even brake for stop signs and traffic lights in addition to cars and pedestrians. And regenerative braking will bring the car to a stop much more quickly than a gas car when the accelerator is not pressed.

I'm trying to think of weird edge cases, but yeah it does seem like the odds are against AP being on in this case. Maybe TACC was on, but even that seems a little inconsistent with the report.

I, for one, am not getting into a car fight with our robot overlords.

On a highway that could cause an accident as traffic behind the self driving car would have to screech to a stop or swerve around. There needs to be some way to get it to pull over onto the shoulder.

This highlights a meta-problem of highways in general: they're very high-speed conduits, which are not intended for traffic to whiplash to 0 MPH in a short distance, where accidents and emergencies can definitely create roadblocks that force traffic to whiplash to 0 MPH over a short distance.

It'd be nice to have a solution to that. There are no inexpensive ones (rails handle this with corridor control... Every N miles, a signal indicates whether it's safe to proceed to the next segment. Some sections of highway have signage allowing for this; most don't).

I've always wanted to run a traffic simulation to see if traffic is eliminated if the highway was partitioned (5-10 rows of car per partition) into several chunks going at a precise speed and requiring cars to maintain some distance between the next partitions behind them. This could be accomplished with some tracking laser following the cars against the wall. Of course this would be ruined as soon as drivers wanted to hop into the partition in front of them, change lanes, etc.

Another slightly relevant idea is to mark intersections with a large red no-go area placed at the calculated point, where, if you were going the speed limit, if the traffic signal changed to yellow and you were in this box you could not safely pass the stop line. I hate having to guess how long a yellow light is (3 to 6 seconds is a large gap).

If you can't slow down in time to avoid hitting the car in front of you when it slows down, you're tailgating, and are a danger to yourself and the cars around you.

The problem isn't when you're tailgating, the problem is when you're comfortably cruising at 80 mph and all of a sudden you realize there's a stopped car in your lane. It can be surprisingly hard to notice the one car that isn't going with the flow of traffic. There are videos of cars getting totaled this way. Not sure I want to know what happened to the passengers.

On busy highways, if your car breaks down and you need to slow, one of your biggest concerns should be to get out of the way asap before someone rear-ends you.

Whether you consider it a result of tailgating or not, pile-ups are a common result of unexpected action on a highway.

What do you do if there is a traffic jam in front of you? You always hit the last car?

I haven't hit anyone so far, but I've gotten rear-ended myself. Twice. Thankfully never been stranded on on a highway like this.. https://www.youtube.com/watch?v=2lnYOlUnsWI

What do you do if a tree or something falls on the road?

That’s why you should stop slowly in such a case. Create a traffic jam behind you.

A traffic jam is a far less dangerous situation than an intoxicated driver.

You shouldn't have to screech to a halt if the car in front of you slowly decelerates.