Toronto needs to implement a few things as potential solutions.
First, make the city more affordable for families to live in, ie. make a 3 or 4 bedroom unit easy to find and male its price compared in sqft the same as a single family home in the GTA (suburbs). Our cities need less commuters and more actually people living on them. Things to look at are missing middle homes, tackle parking requirements, take a look at fire codes and zoning in cities to allow low rose 6-7/story developments aimed at families and not investors.
Second, implement a greater increase in transportation infrastructure, this means closing streets to only transit such as trams, buses, taxis, and cycling. Focused on making the city walkable and livable from a pedestrian standpoint. This will cause more people to want to live on the city. The concept of a 15min city is the key.
Third, implement a low carbon, or low emission zone in toronto. Specifically starting in the downtown core, probaby up till saint clair or maybe even Ellington. Prevent larger and less file efficient cars for coming into the city to promote greater transit and less pollution, again urguing more people to choose to live on the city.
Fourth, look at infrastructure planing in Ontario. Out road and street design are not well thought out. We need to stop developing "strodes" and classify our roadways between streets, roads, and hyways for effectively. We need to cut down infrastructure costs as well, we can do this by cuting down on the amount of signaled intersections, and instead we should look at roundabout or traffic circles as much as possible. Most moneys cities spend are in the continued maintenance of traffic signals/lights. A roundabout is only built once and the maintenance costs in substantially lower.
Taking about classification of roadways, Ontario has almost no high speed roads, instead we implement "strodes" which are neither safe for pedestrian traffic or cycaling. This also sucks for transits. Instead we need proper design where hwys spill into high speed roads, which meet low speed roads, then into low speed streets and residential neighbourhood streets. We treat everything either as a hwy or a road at the moment, and each road has multiple driveways whicj causes congestion.
In the example of the Gardiner its was originaly designed as a high speed road with a limit of 90km, but its currently treated like a hwy. All the off ramps also empty out directly onto low density low speed streets.
IMO, the only place in all of Toronto that shows some sense of planing is a small section of the Allan road traveling north. The section looks like this.
You have the 401 hwy connect you to the Allan Rd (high speed road with no lights), empty out into a low traffic low speed city street, which then connects you into a suburban low speed speed. You have no traffic lights in this location (except the one intersection across the Allan at the top right), this section should really be a full two lane roundabout.