[TimBurman]

In my city, the signal controller registers when a pedestrian pushes a button for the walk signal on a crossing that conflicts with a protected left turn. If it is fully protected, with a green arrow followed by red ball, then pedestrians are not given walk signals during that turning phase but prior during the through phase in their direction. If it is protected-permissive, when motorists see a green arrow followed by a green ball, then the pedestrian gets their walk signal ahead of the turning traffic, so they can clear before the left turning vehicles intersect their crosswalk. The collision you saw is the same issue that happens with right turn on red. The pedestrian has a walk, the car behind them turns into the pedestrian, even though they have a better view than a left turning vehicle of the nearby person. One alternative is to give separate phases to each traffic movement, such as the pedestrian scramble where all directions of pedestrians go with all vehicles stopped. The issue with delaying the left turn while the pedestrians go first is it increases cycle time or gives a greater percentage of cycle time to lower volume side road traffic, which tends to reduce the service level for most motorists waiting at conflicting red signals for these movements to complete. Lower service levels lead to more complaints, especially when there are thousands of vehicles per day vs. 100 pedestrian crossings, but Traffic Engineers have to fight for those pedestrians using what is often a difficult compromise.