[matt-attack]

I noticed that change recently and assumed it was motivated by Tesla. There are certain things we all take for granted when driving. A huge one that we probably don’t give much conscious thought to us this:

How do we know if the lane to the left is ok to go in, or if it actually is for carrying oncoming traffic?

You’d like to think that one way though not the only way, is to look for a double yellow line. As in, double yellows always separate opposing traffic so never cross them.

In CA though, double yellow was also chosen to separate the carpool lane as OP mentioned. So there was actually a really mundane case where driving to the left of a double yellow was actually fine. Seems very confusing to an autonomous car that’s operating at the mental-level of an 18mo old.

[tobyjsullivan]

You are giving way too much credit to autonomous vehicles in this theory. Line colours are standard throughout all of North America (that I’ve seen so far). Yellow means what it means. This carpool line experiment would have been confusing to any driver seeing it for the first time.

Imagine a tourist on that highway for the first time, at 3am, when there’s no traffic. Can they use that lane? Can they pull a sneaky u-turn and start driving the opposite direction?

What if I’m driving down the highway, effectively on mental autopilot, and suddenly become aware that I’m on the “wrong” side of the yellow line? How would I be likely to react?

The opportunities for misunderstanding by normal humans seem plenty.

[mikestew]

I noticed that change recently and assumed it was motivated by Tesla.

My '11 Nissan Leaf couldn't even have LED taillights because the Feds said "no". Tesla isn't going to march into some DOT office and demand that the color of the lines be changed to accommodate them (I mean, they could, but the laughter would drown out the conversation).

CA changed it because not only was yellow against federal guidelines, but also because I personally believe it was a stupid choice to begin with (for reasons others have already listed).

[throwawayboise]

Yellow lines separating oncoming traffic is not universal though? I believe in the UK that the center lines are white?

[tannhaeuser]

Living in Germany and having only driven in Mexico (City) as far as the Americas go, I admit to not understand what yellow lines signify to US drivers, like at all ;) At my place, they're used for temporarily "overriding" regular white lines eg at construction sites, and only for that purpose.