I don't see anything wrong with comparing ourselves to Melbourne. It's not like it's a small city, it has several million people and a bigger streetcar network than Toronto. For bigger cities with streetcar systems in dense areas, consider Tokyo, Hong Kong, Osaka, Milan, Moscow, and St. Petersburg.
And while I have no doubt that closing King to cars would improve the line, of course it won't solve all our problems. It will still be quite a bit slower than a subway and it will do nothing for Line 1 crowding...which is the main reason that the DRL is finally on the front burner. I can't see it having any impact on the case for a new subway downtown, which can relieve Line 1 and provide the reliable east-west travel that the downtown core needs.
To start I'm just going to make it clear on a few things so no one thinks I'm spouting Nayshunal rhetoric, or that I'm against the general idea of a King transit mall. I'm a
huge supporter of streetcars, LRT, and pedestrian zones; and would love for TO and the GTHA to have dozens of these.
Tokyo, Hong Kong, Osaka, Milan, Moscow, St Petersburgh... although I'm not really knowledgable with them, and don't at all doubt that they have extensive surface tram systems operating through each of their respective CBDs, I'd wager that each also has several grade-separated rapid transit lines passing through their core areas. Whether it's a heavy rail subway, or a Eg Crosstown-style premetro/stadtbahn (where a tram is tunneled beneath the central part of the city), or a combo of such systems - I don't think it's a safe comparison to TO's CBD. We have
ONE such line through ours (Line 1), with every other line throttled from being stuck on the surface. Even North York Centre has more (Lines 1 and 4), and soon Yonge-Eglinton Centre (Lines 1 and 5). I really can't think of any major city (Alpha and upwards) that has relegated their downtown to such backwardness as building only one line through their CBD.
Yes the DRL thankfully got bumped up in the Big Move from the 25yr to the 15yr plan. But unfortunately the supposed '15-yr' plan has been stretched out to +25yrs, and what's being highlighted now is not what was proposed during the Miller era. The original DRL to be built post-TC was to be a route that was one part Yonge 'relief', but 100% a subway across the south end of Old TO, through the CBD, from Pape to Dundas West, and in operation by ~2031. The plan has now been downgraded considerably - with the portion west of Osgoode dropped from the OP and RTP indefinitely, and the abridged Pape-Osgoode section to be in operation by ~2035.
Almost a quarter century before the Big Move we had the 1985 DRT/DRL plan. This was also a means of Yonge Relief, but more to the point it was the #1 shortlisted solution in a cohesive plan aimed at tackling transit within/across downtown and Old Toronto. How? By creating a grade-separated rapid transit line across the south end of the city. Every option but this one solution was soundly rejected as insufficient (yes, even surface streetcar improvements). This is somewhat surprising in retrospect, considering that Old TO was projected to see minimal growth - with the majority supposedly to occur in the boroughs' "Centres".
Prior to
that there were a significant number of plans spanning many decades that all led to the same answer: any crosstown rapid transit route needs to be grade-separated (tunneled/trenched) across the south end of the city. This wasn't one or two ideas, but a long series of separate studies undertaken between the 1910s-1980s. The ghost Lower Queen from the early 50s should serve as testimony to this long-standing conclusion. Considering traffic + development has grown above/beyond what anyone in the 1900s could've ever imagined, I think it's pretty obvious the same conclusions spanning a century would be the same conclusion today (arguably moreso): That is: we have to create a grade-separated line through the core and across the south end of the city.
Again, I'm all in favour of improving the 504's speed/reliability/capacity/frequency. Not to mention closing roads to cars and creating pedestrian malls. But unless we decide to holistically plan the King transit mall in tandem with the complete Miller-era DRL - and I guess tunnel the 504 for ~2km through the core, convert to 2 or 3-car consists, and LRTize the portions to Dundas West and Broadview stations - I think it's clear that any net gain in 504 service will be overrun on its first day. The current demand, latent demand, and growing demand will swamp it otherwise.
There's another thing that seems fairly apparent: money, resources, manpower are all finite. So unless this King transit mall is financed by donations specific to the project, planned/engineered by volunteers, and constructed pro bono - I think it's safe to say that it will by default divert money, resources, manpower, and attention from pre-existing projects. It might be a little or it might be a lot - we don't know at this point. But the TTC and Planning dept is only so large. However what we
do know (and was stressed at the Relief Line meetings) is that the DRL needs all the funds and support it can get.
So until I see a thorough EA for a DRL stretching all the way to at least Dufferin (that's funded and near shovel-ready), I think we should tread lightly when it comes to focusing attention toward new ideas that serve the same/adjacent corridor as the DRL. One hundred years of studies all pointed to the same conclusion - and a transit mall wasn't one of them. Nor was SmartTrack and new GO stations for that matter. The core of the city is in the mess it's in for no other reason than delaying, not building, underbuilding, politicization, and tackling new ideas (instead of building something deduced numerous times over the last century).