Are not the 'key' lights controllable by a central computer system? I thought it was possible to make on-demand changes to the lights.
According to my sister, who has worked for various highways departments, you can override many lights from the central control room for the area. She once described to me watching as a controller gave one of their staff a green wave to get to a meeting, watching him on traffic cameras & switching the lights as he approached.
Of course, they wouldn't do that when traffic was heavy. Cause far too much disruption.
But - and it's a big but - inadequately planned changes to phasing of lights could cause chaos. It's all right doing a bit of ad hoc manual overriding, but making permanent changes without carefully modelling the consequences has some of the same risks as trying to repair a watch with a hammer. Get wrong - cue gridlock.