Spadina isn't a "major transit line"....it's a short LRT line. Putting LRT underground isn't cost effective. We're lucky they spent the $105 million to put in what we got. Surely you aren't suggesting that Spadina should have built as a heavy rail subway (even if we had a $billion to do it)?
The problem with Spadina, is they accommodated cars too much. They should have NEVER built the left-hand turn lanes with delayed greens. They should have killed one lane each way, and widened the sidewalks and installed bike lanes. Spadina is a prime example where cars should have had their asses kicked. But hey, this city is still not prepared to face that reality, so it was what we got...or nothing. I'll take what we got.
A lot of the problems on Spadina is an unavoidable fact of logistics on such a busy downtown corridor. Spacing stops further apart won't help anything....traffic light priority won't work either. What Spadina needs is those big new streetcars.