Richmond Hill line is tough, because it has so much potential, but all options turn out to be quite expensive.
The current issue of Richmond Hill line is this: the current alignment is quite slow through the Don Valley, and it goes through a flood plain.
The solution to fix the flood plain is about $1.3 billion. Not cheap and will take time.
There is another option: Metrolinx purchased the CP Don Branch back in 2011. It offers a much straighter and faster route, and avoids the flood area.
Unfortunately it too has problems: namely that there is a lot of work to be done to refurbish and replace the track along the alignment, part goes through a very active CP mainline, as well that part of the alignment was ripped out and replaced with a bike path,
Now, that bike path, the Leaside Spur, is actually land owned by Metrolinx and the city has a temporary provision to use it as a bike path. At any point Metrolinx could revoke that permission and build a rail line in their. However, the question is, would they?
As you can imagine, the NIMBYISM would be out of control. That spur goes through a quiet neighbourhood of houses abutting the spur line.
The only thing I could possibly ever see being allowed on that area, would be some Tram-Train LRTs that are both compatible with heavy rail, but very light and quiet. That way you could sell to the locals of that area that they are getting an LRT, much like the Artbus corridor in Vancouver.
That still leaves Transport Canada to contend with. Metrolinx owns the lines from Union to the York sub just north of Steeles, and as we see with the Ion LRT in kitchener, TC will allow special provisions for LRTS to run on heavy rail spurs. However north of the York sub CN owns the lines and operates freight on it. I doubt TC would allow an LRT to operate there. Not including over the CP mainline that you must navigate to get to the Don Branch to downtown.
Furthurmore, it appears that VIA will want to use the Don Branch for its HFR trains, so scheduling will become even tighter on this line.
So as you can see there are a lot of issues with Richmond Hill, and solutions, but none of them are easy or a simple cost effective one.
Personally I think that Metrolinx should just operate a fleet of DMU's on the RH line while it fixes the problems with the flooding and the Don Branch connections, as it will be a long time coming before they offer anything better on this line.
