While generally I support the removal of highways. I'm more in favour of reconfiguring the expressway at Eglinton. Yonge and Eglinton is a major business district and I think it's smart to maintain highway access.
I'm not sure I agree they have highway access. I don't know what origin/destination surveys show for users of Allen Road, but I'd be surprised if a large amount of that traffic was bound for Y-E in the AM Peak.
Suffice to say Allen Road is 3km from Yonge and Eglinton; and the City is in the process of narrowing Eglinton Avenue to support Cycle Tracks and wide sidewalks, reducing current throughput for cars.
But I think we could do this while also improving the pedestrian experience - it would just take some expropriation.
Example: raising Eglinton at Allen Road by ~3m to allow off ramps to pass under Eglinton and into the middle lane where a traffic signal would be placed. Not only would pedestrian conflict points be reduced, but phased traffic signals could also improve traffic flows. Expropriated lands could then be regraded and developed with increased density.
Assuming the origin/destination surveys supported the notion that a material amount of Allen Road traffic were bound for Yonge-Eglinton.........what you propose has 2 overt issues to me.
The first, I have noted above, that the City is actually reducing the car-carrying capacity of Eglinton in favour of cycletracks and wider sidewalks.
The second is the cost and political issue of the expropriation you're identifying.
A quick glance suggests to me that you would be making the 13 Division police parking lot completely inaccessible (if the road is 3M above that grade level.); a replacement building will start at 50M and could be double that.
It might also impair access to Winnett Avenue. Depending on the turning radii of the ramp (which would be over the Crosstown tunnel), there's no chance that's under a 6% grade and I think its likely higher.
The ramp portal would likely eat into and impair access to Ben Nobleman Park as well.
That's just the off ramp; and only at Eglinton. That's no small matter.
Oh, and 3M is not sufficient to support truck clearance given that you're to have a deck under that raised road w/the ramp passing underneath. I think you'd need just about 4M for clearance, then another 1M on top for the road deck above.
Since pedestrians and cyclists would likewise have to pass over the ramp, you're now putting them on a 10%+ grade which is in excess of current standards for those with Wheelchairs, where every effort is made to maintain a 5% or less grade.
Never mind the poor merchants on this section of Eglinton that have endured years of construction and will lack enthusiasm for more.
In the above scenario, I'm not sure you really make pedestrian/cycling life much more comfortable at the interchanges; the problem of excess traffic entering too small a road to support it remains, and it doesn't address reconnecting neighbourhoods, or The Beltline, creating new parks or housing.