Rainforest
Senior Member
LRT is the most expensive option out there due to the extra large tunnels needed and mostly due to switching the SRT to LRT. Most of the cost of the SRT switch to LRT is due to all the stations having to be comppletely redone due to having to "raise the roof" due to the extra height needed to accomodate LRT. It will be more expensive than much higher capacity subway/metro, SkyTrain, or monorail which just require track work changes. SkyTrain would require no changes at all and have the extra savings of not having to build a totally new LRT storage and maintenance centre.
Most of the costs are the extension to Sheppard / Progress, the rebuild of Kennedy station, and the rebuild of tunnel between Ellesmere and Midland. All those costs are needed for ART as well.
Raising the roofs is a minor component.