[PeterisP]

The problem with busy crossings is that if both cars and pedestrians have 'green' at the same time, and the traffic is busy (i.e., someone would be walking/driving for most part of the green light), then it's very inefficient for cars needing to make the right turn, that need to cross with the pedestrians. In some street plans (e.g., interleaving one-way streets w. no left crossings) the right-turn traffic is very heavy and has a separate lane; so delaying them is bad.

There are two okay solutions - either you desync the lights, so that there's some gap where the pedestrians have a red light but cars already/still have green, so that they can make that turn; or you make a 3-phase crossing; A-cars have green in one direction; B-cars have green in the other direction; C-all cars stop and pedestrians can cross across and diagonally. It works okay.

What's not a solution - 'right turn on red' doesn't solve it; this problem matters in heavy car/foot traffic, and in such traffic there aren't any safe opportunities to do so.