It's set up like this - busy avenue with lanes (left to right) 1, 2, and 3 enter into roundabout with circles (inner to outer) A, B, and C. The problem is that half way around the circle, where the avenue continues, A, B, and C then have lines indicating that you can either continue on the circle or move in a perpendicular direction to the circle and exit back such like this A -> 1, B -> 2, and C -> 3. And that's what everyone does. The problem is If someone from C is going around the circle, they're going to t-bone anyone going A -> 1 or B -> 2, and there's no moment to prepare because A or B is going to be suddenly cutting in front of them.

Or to visualize it another way - if you can image those intersections where there are two right turn only lanes, and one lane to the left of them that's right turn or go straight. Now imagine if all three lanes were right turn or go straight, and everyone made right turns - but if someone in the far right lane is going straight, they're plowing into the cars turning in the other two lanes.

After years they eventually fixed it and made the two outer circle lanes right turn only, which is what they should have done at the beginning. But even there they screwed up, because there's a street that enters the circle right after the right turn only signs, so if someone is entering from that direction and isn't familiar with the circle it's possible for them to ram into the other cars.