system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: How do self-driving cars manage large intersections with multiple traffic signals?
gpt
First of all, keep in mind that there are no finished, commercially-available self-driving cars that automatically handle traffic signals...yet.

Tesla's self-driving features only handle highway driving and parking, for example - they don't handle stop lights and stop signs.

Google's is the furthest along based on public information but it's still years away from being ready to fully autonomously drive. So this type of thing probably isn't completely solved yet.

One of the keys to Google's self-driving car is that it uses Google Street View data plus everything else from Google Maps driving directions - so it actually knows how many lanes there are supposed to be at every intersection, and which ones are turn lanes - before it can "see" any of the signs. That helps it know how to interpret the traffic signals.

That makes things much easier - it's not trying to understand every intersection from scratch, every time. It knows what to expect and only has to detect if for some reason the intersection isn't what it expected, like if it was recently changed.