Except, I believe that I heard from someone that, during the planning for the 417 Bronson overpass replacement, the MTO asked the City if they wanted to lengthen the overpass so that an extra lane could be added to Bronson. This is purely rumour, but I believe it to be true. Since the City would have had to foot a huge bill for the change, it declined the option and the MTO did a Rapid Bridge Replacement with a like structure, at its own cost.
What I would like to see happen now:
Pipe-Jack Tunneling should be used to create pedestrian/cycling passes under the 417 on each side of the Bronson overpass. Then the sidewalks along the section of Bronson under the overpass can be removed, and that space allocated to the missing south-bound left-turn lane.
Get rid of Chamberlain west of Percy. Connect Imperial out to a signalized intersection with Plymouth and Bronson. People who want to go east on Chamberlain will turn at the new ramp intersection.
FIX THE 417 OFF-RAMP to Catherine, and the Catherine/Raymond intersection with Bronson. There should be a separate lane to the 417 on-ramp, west of Bronson. Also, the MTO should not ‘hog’ the two left-turn lanes onto south-bound Bronson. It should guide drivers, preferentially, to the inside lane – but still allowing overflow to mingle with people from Catherine who are trying to turn left.