micheal_can
Senior Member
I don't even think it would be physically possible to run the line under the Don Valley. The distance from the future Mortimer/Cosburn station to the valley is at most just over a kilometer and iirc the TTC says its maximum grade for its trains is something like 3% so is it even possible to drop that much altitude in what is at most a kilometer? We aren't using rubber tire or LIM for the line so we are pretty hamstrung on this. Of course there is also the absurd cost of tunneling that deep for what is in this case literally no reason.
EDIT: as well bridging the valley would allow the RLN to be shallower which has obvious cost and construction benefits. Can you imagine if the BD was planned to be built under the Don. There probably wouldn't be a BD since the tunneling alone would have eaten nearly the entire budget.
Ok you math wizards, the depth of the Don Valley in that area seems to be about 100+m. Lets add 20m to be below the river. So, lets say you need to drop 120m How far at a 3% grade could it be done in?