How the Cardinal leaves Chicago

I rode the Cardinal out of Chicago in mid-November and noticed that we did not exit the old Pennsy maineline at Colehour Junction. I asked the conductor and got her cheat sheet of various mileposts and railroad names but I can’t piece it all in sequence. The railroad she has listed:

CN MP 31.0-25.2 (ex GTW?)

UP MP 20.0-9.0

BRC MP 16.0-15.3

NS CP 518-521

METRA for 4 miles

I thought she mentioned something about a quick ride on B&OCT for probably not even a train length.

Can any one help me unravel this maze?

The Bernice Cutoff, which began at Colehour Junction, has mostly been abandoned. The Cardinal’s route out of Chicago is as follows:

Chicago Union Station trackage to 21st Street, former C&WI (now Metra/UP) to Dolton Junction, CSX/UP joint line (former C&EI) to Thornton Junction, GTW to Dyer, CSX (former MON) beyond.

Thanks for the quick reply. The conductor mentioned the B&OCT as a link between two of the other roads. Is that true and where would that occur?