I'd imagine that CP will be so happy to be rid of it that it will disappear the night after the first in-service GO train crosses the new span...
It won’t take long, but it’s more complicated than that, because the signalling has to be modified. Even though the diamond won’t have any opposing movements to clear, the signals protecting it have to be removed and the circuitry altered to bridge across the gap. (the “approach” signals on either side of the diamond may ned to be reprogrammed to convey different indications under different conditions, and the spacing of blocks may be changed to simplify and increase speeds).
IIRC when the West Toronto underpass was completed, the physical track components were torn out and replaced with straight rail a few days later, but, it was several months before the signal circuitry was updated, and in the interim the CP RTC’s continued to clear the signal at the ”diamond” just as if it was still there.
- Paul