I still keep misreading those big white triangles for opposite direction arrows, and sometimes that's very confusing:
To be honest, I don't even know what do they stand for. My only idea is that it's an invitation to look around before moving forward, so the apex is for the eye and so the triangle is the field of view (sounds like a weird explanation, doesn't it?)
Back in the days when I was still struggling with the left-hand traffic mistaking with the direction when triangles were the only indicators happened more often to me than I'd rather like.
Be careful if you have the same problems.