The proper rules[1] of a 4 way stop are probably pretty straightforward to encode, and probably easier for a computer to apply than a human, but the real issue is that you can't trust the other drivers (or AIs) to understand/follow them consistently. So the interesting part is how these kinds of systems can almost instantly react when another driver starts to go, and let them go.
In NYC, where I live now, the de facto rule seems to be if you hesitate at all then the other person just goes, rules be damned. In the rural south, where I'm from, there's a lot of "no no, you go first" waving/gesturing/light flashing, which I'm curious if/how a self driving car would handle. (Do we need to give the self driving cars hands to gesture with?!)
The car stopping if another car goes before it brings up another issue. If self driving cars start showing up on the road and are recognizable, you'd be able to "bully" the self driving cars since you know it'll always give right away. Imagine being stuck on an on-ramp behind a car that is programmed with infinite patience and extreme risk aversion; you could be sitting there quite a while.
That's not the real issue, that's just the initial domino. The real issue is how self-driving companies will combat that. They'll surely want to record film at all times and have a pipeline to law enforcement to curb suspected bullies. It's often the over-correcting solution that becomes the bigger problem. There are analogues in other human-robot interactions.
Waymo resolved this early on by encoding the human resolution into the action. Stopping as required by law, then moving forward slowly until the next action is more clear.
Imagine if cars were given the same authority to generate citations as redlight cameras and schoolbus cameras. They'd be cheap to free and financed by kickbacks from law enforcement.
I imagine if enough self-driving cars were on the road, that would be less of a problem, because more regular speeds & distances between cars would allow for more opportunities for merging. Perhaps even between-car negotiations of merging or 4 way stop type of behaviour.
I think we're quite a ways away from that though - hopefully not as far away as the flying car thing :)
> In NYC, where I live now, the de facto rule seems to be if you hesitate at all then the other person just goes, rules be damned.
This has been my experience pretty much everywhere I've driven, which includes a half dozen or so European countries and about as many U.S. states. Notably though I've never driven in New York, state or city.
My experience is that in larger cities, and cities with a lot of tourists, this "aggressiveness" seems to be the norm. I put that in scare quotes because I'm not sure I'd call it aggressive, I just feel it's the pragmatic way to break the tie.
Maybe that's why this is my experience everywhere – I'm that guy! (My apologies to all my fellow drivers out there!)
Wouldn't the data decide what the rule is? I'm guessing if in NYC, a more aggressive driving style is the norm - the models and the pipeline should be capable of adjusting to that.
Lawyers will define what the rules are for a manufacturers self driving cars. After all, any accident at a 4-way stop will immediately result in blaming and then suing the manufacturer. And what are they gonna have for a defense? "Sorry, your honor, we use machine learning to decide how our car drives--as a result there is no real way to truly understand how our car will react to every situation it encounters".
In NYC, where I live now, the de facto rule seems to be if you hesitate at all then the other person just goes, rules be damned. In the rural south, where I'm from, there's a lot of "no no, you go first" waving/gesturing/light flashing, which I'm curious if/how a self driving car would handle. (Do we need to give the self driving cars hands to gesture with?!)
1. https://en.wikipedia.org/wiki/All-way_stop#Operation