Here is an interesting article, instead of subways, use the underused GO lines:
http://www.thegridto.com/city/politics/tunnel-vision-is-plaguing-the-future-of-transit-in-this-city/
http://www.thegridto.com/city/politics/tunnel-vision-is-plaguing-the-future-of-transit-in-this-city/
On Monday, a group called Transport Action Ontario released a proposal—the result of two years of research—suggesting that the underused GO rail corridors in and around Toronto could be easily and relatively cheaply converted into “above-ground subways” that would provide high-speed train service across the city and way out into the 905. Their proposal offers the kind of breathtaking map that gets all of us excited: seven lines snaking around the entire city with more than 50 stations in Toronto. Their research says the whole thing could be done much cheaper than the cost of subways or even LRTs, while still providing huge capacity, and may be completely finished in fewer than 20 years.