steveintoronto has brought up tunnelling and geotechnical challenges with having the line cross above the Don and DVP but I contend there are simpler geometry issues that make this essentially impossible (nothing is "impossible" but the scale of impacts do not make it feasible).
One just has to look at the plan views of the proposed station, focusing on where the platforms are located relative to the rail corridor:
View attachment 184551View attachment 184552
Scenario 1: At-grade (elevated) with the rail corridor
Not feasible, due to the obvious conflict with the existing rail corridor. Btw, I see absolutely no chance of this line being interlined with the LSE corridor, which is the only way this scenario could ever resemble something that is feasible. Raise it over the rail corridor? Non-starter, again for obvious reasons, plus the platforms would have to be on a serious gradient.
Scenario 2: Lower to Eastern Avenue grade east of the DVP
We're now in conflict with the Broadview Avenue extension, not to mention the rail embankment, and Eastern Avenue when the line turns northward. Remember, the platforms have to be at a zero gradient and their eastern ends are at the rail corridor.
Scenario 3: Lower below Broadview Avenue profile east of the DVP
To clear the DVP and then to be sufficiently lower than the roadways and subsurface utilities on Eastern and Broadview, that's one heck of a roller coaster and our platforms will not be at a zero gradient. Plus, if you're now diving below grade for the station, why not just tunnel the river and the DVP?
Bottom line: this is another example of wasted time and money with only the consultants on poorly scoped, cost-plus assignments benefitting from it.