nfitz
Superstar
The bedrock downtown is shale, and can be very soft. This isn't like Montreal where you can just tunnel through the bedrock willy-nilly. You may even need to underpin.IIRC the difference, at least with Queen and Osgoode, is the OL tunnel will be built into the bedrock at those stations, so they won't have to underpin the existing subway tunnel the way they did with Eglinton and Eg West. That's why in the diagram for Queen station, the OL station is largely built to either side of the existing station. Not to say these stations won't be complex or could slow down the project, but they aren't being built in the same way that slowed down the Eglinton transfer stations, thankfully.
I'd think the biggest difference for the Ontario Line is that Osgoode and Queen are part of the main contract, and will be starting with the others, rather than a later contract, and playing catch-up the whole time.
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