Why do you need to know if they need to turn? If you are far enough left to give them room on your right to turn right, it shouldn't be an issue. If they're going straight, they'll stop behind you. If they're turning right, they'll pass you on the right and turn right. Regardless what the motorist behind you is planning on doing, your stopping position in the lane should be the same.

Stopping in the "middle of the lane" that is relatively wide means stopping at about the "right tire track" of cars going straight. Unless the lane is wide enough for right-turning cars to squeeze past cars stopped further to the left who are going straight, this is not far enough to the left to let the right-turning cars pass you on your right. In that case you should be stopped further to the left. Basically, if you have to move left from your initial stopped position to let right-turners turn right, then your initial stopped position is not far enough to the left.


Yikes! I've never had that happen. Perhaps you're stopping too far to the left?
Or is this in a lane from which left turns are also allowed? All of the above I have written assumes a straight-or-right lane, not a left-or-straight-or-right lane. In that case stopping near the left indicates your intent is to turn left, which makes stopping on your right and passing you on the right, even by motorists going straight when the light turns, to be appropriate. Especially if the left turn is not protected by a left arrow signal...

Serge