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New green light chimes shed light on FSD lane awareness

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Tesla recently rolled out an option to enable a 'chime' when the light you're waiting at turns green (regardless of whether AP is on).

The traffic light renderings were always so crude that I often wondered whether the car understood which lane was controlled by which light. But since enabling the chime, I've been pleasantly surprised. When sitting in the left turn lane of a multi-lane road, the green arrow turned green (while the other lanes remained red) and the car chimed to let me know my lane could proceed. Same thing when I was sitting at a light waiting to turn right (this particular intersection has a dedicated light for right turns).

It's a small thing, but I found it encouraging.
 
I guess they’ve been marking the “relevant” lights in the UI for a while, but the visualization has been sort of subtle - the lights that it thinks are relevant for you will get marked a little brighter. The chime works with this information, I assume. Not sure if it uses heuristics or mapping tricks for this.

I found an intersection yesterday where there are 2 lanes with both only going straight (the cross-street is a 1-way T junction), and the traffic lights for the cross street are close enough that they get picked up and rendered as if they’re controlling the same direction as the “valid” lights. Would be curious to see whether the green light chime would activate on those, as I couldn’t quite tell from the visualization alone...
 
OTOH, this morning we stopped at a red light and noticed the truck’s turn signal in front of us was being picked up as a traffic light also, with the result of having a traffic light image appear and disappear, in addition to the ones that were static. Was interested to see how that would play, so I engaged AP. Sure enough, when all the real lights turned green, the limit line stayed red and we stayed put, due to this intermittently appearing phantom light.