Always risky taking renderings too literally - but - the track drawing shows the likelihood of the 4-track line being used as two express tracks (not accessible from the platforms) and two stopping tracks for local trains making all local stops.
That leads to a scenario where the local tracks are used by the UP trains making all local stops, interleaving at Wice with other local trains from Bramalea or Mount Pleasant, all using those two local tracks.
Meanwhile, express trains from wherever use the other two tracks, perhaps making selected stops (as Bloor, Mount Dennis Weston, and Woodbine will have platforms) .... but definitely not stopping at St Clair.
There was lots of talk of this configuration, and it sort of works this way already with three tracks - but this is the first time that has reached the artwork, to my knowledge.