I'm also not crazy about the idea of vertical white bars having multiple different meanings depending on the intersection. Especially if more signs is what we need to explain the meanings.
Oh, and the taxi exception further complicates things.
This is already the case! The symbol is currently just a blanket transit priority in our regs. The taxi exception would not work with this, no transit signal would - if you have anything that isn't a transit vehicle going through the intersection you
need a regular traffic light, that's not really negotiable. The problem with King is that it is a half baked pilot that no one seems to want to pick up and actually complete from the ground up - you can't solve it by tweaking signals and signage alone.
Let's say for example you show a white bar for Eastbound traffic.
Transit vehicles turning left would conflict with pedestrians on the North crosswalk, and transit vehicles turning right would conflict with pedestrians on the South crosswalk. It's therefore not possible to give those crosswalks the walk signal at the same time as the white bar.
Transit bar = fully protected left turn and right turn.
Pedestrians conflict with left turn and right turn.
The current regs require the transit priority to be the only movement during the phase anyways, you wouldn't have concurrent pedestrian movement and the phase only lasts as long as the vehicle needs to clear the intersection which is shorter than any pedestrian phase would require. If you wanted to allow for transit through movements with pedestrians, you would require a dedicated 3 light transit signal (under current regs).
How do you expect the TTC to solve the problem when they have no alternative way of showing a left turn arrow for transit vehicles only?
I feel like I'm banging my head against a brick wall. The HTA allows any transit movement during the white bar priority phase. If the TTC doesn't allow this, that's their own rule. There's nothing to change in the HTA (unless we just go to full 3 light white bar transit signals, which the MTO seems reluctant to do). It would be up to the transportation engineers designing the intersection to ensure that there are no conflicts, which is possible because transit routes are planned and drivers are professional. The scenario where you have a conflict in transit movements, where one is going straight and one in the opposing direction is turning left and they both show up at the same time, you would know if that possibility exists because of route planning. You can handle this one of two ways, use the same phase and let the two drivers sort out right of way (straight movements first), or phase each direction.
Regardless you would not be able to use a transit priority signal on King for any real benefit if the carve out for taxis remains. Taxis would still require a green signal, which cannot run at the same time as a transit priority. King also allows bikes, so if you removed the standard green you would need a bike signal (I don't remember off the top of my head if the HTA allows for bike on ped signal movements, but that would be an additional sign).