[emathias]

Crossrail seems sucky at the airport end of things unless they do something with the terminals.

To me, it seems like a deep tunnel with only three (O'Hare, the Loop, McCormick) stations would be ideal. You could have one station under O'Hare, and design it so that future HSR could use the same tunnel and station if that ever actually happened, one station under the West Loop, and one station at McCormick ready to also connect to future HSR. Design it right and it forms a backbone for the West Loop Transportation Center that's been long planned but never any movement on. I mean, ideally you'd drop people under Lasalle at Clark/Lake or use Block 37 but I don't see anyone actually advocating that anymore so the deep tunnel, three-stop solution seems best. Deep tunnels with only stations at the ends and one in the middle wouldn't be all that expensive compared to "normal" subways.