I have a similar issue on my commute home (by car). There's a busy 3 way island and cars in the lane to my right (strictly speaking it's straight on but it's still the junction to my right and so I have to give way) can either turn left, and so I can go, or right, and so I have to wait for them to pass in front of me.
The problem is that very few of them bother to indicate and so it's very cat and mouse. I have to assume (for safety), if they're not indicating, that they're going to be turning right. I often sit there like a lemon as car after car turns left
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