This may be of interest to some.
I live near the Dundas and Lansdowne intersection, which is currently undergoing reconstruction. I was chatting with one of the TTC workers the other day and he told me that they discovered a high pressure gas main directly under the road bed, and as a result they won't be installing the curve from westbound Dundas to northbound Lansdowne as they would have to pour concrete directly on top of it, which the city won't allow. He said that they will have to decommission and reconstruct the gas main over the course of the next year, and they will likely install the missing curve next year during the scheduled reconstruction of College/Lansdowne.
This checks out, given that I had observed that they weren't using heavy equipment on that corner and all the demolition work was being done by hand, slowly and painstakingly, by workers with jackhammers. I'm curious to see whether they're able to reopen the intersection in time. Definitely not looking forward to having the intersection ripped up again a year from now.