I'd suggest the MBI book Penn Central by Peter Lynch. It offers a very comprehensive look at the Columbus area and how operations evolved from separate PRR and NYC divisions into the PC era. Sadly, the Columbus area, as part of the Southern Division, was the area with the most redundant routes. PC and CR lifted about 48% of the tracks in that area between 1968 and 1999.
"It is highly likely that the 1990s were an overrated decade."