Calvin. The city owned the streets and ravines, so any route that used an existing ravine allowed for a surface rail segment. Under streets there was zero land

Calvin. The city owned the streets and ravines, so any route that used an existing ravine allowed for a surface rail segment. Under streets there was zero land cost, just the dig and shaft cost through the clay, garavel and hardpan that underlies Toronto. Going under houses was possible with forced purchase via eminent domain of the underground rights - but had a cost as tunneling cost more than cut and cover in these early days. We now have integrated tunneling/lining machines, so that is what they do not as C&C has large infrastructure relocation costs, whereas deep tunnels encounter only whatever is there. They extract drill cores on the planned routes these days to bypass any aquifers(wetted sand/gravel etc). The large east west light rail transport (LRT) used a combination of tunneling and surface/ravine open cuts. https://en.wikipedia.org/wiki/Line_5_Eglinton https://en.wikipedia.org/wiki/Line_5_Eglinton https://en.wikipedia.org/wiki/Jane_LRT https://en.wikipedia.org/wiki/Jane_LRT As you can see by the timeline, it was all fits and stops