[bunderbunder]

I'm sure there are civil engineering issues I haven't thought of, but it seems like there would be a lot less tunnel to bore if they take the existing line that already goes from downtown to O'Hare and just convert it from being partially underground to being completely underground.

[MisterTea]

how do you do that without service interruptions?

[bunderbunder]

You don't.

Don't worry, blue line people are used to it.