Athens Subdivision (160.230 MHz):
The Athens Subdivision is the former C&O/Hocking Valley line from Athens to Columbus. Built to haul coal from the southeastern Ohio coal fields to Lake Erie, it began a downhill slide when the southern Ohio coalfields were either depleted or passed over in favor of lower-sulfur coal. The line has recently been downgraded to the Athens Industrial Track and is under the operational control of the Parsons Yardmaster.
Northern Subdivision (160.230 road, 161.520 dispatcher):
The Northern Subdivision was bult by Chesapeake & Ohio in the 1920s to gain a company-owned route between the C&O main at Russell, KY and the Hocking Valley lines at Columbus. Traffic between Russell and Columbus originally utilized trackage rights over N&W between Portsmouth and Columbus; when N&W declined to renew the trackage rights agreement, a new route was imperative.
The Northern Subdivision was built to the highest standards of the day, and is still one of the best-designed pieces of railroad in the country. Boasting light grades and easy curves, the line continues to host coal, chemical and manifest traffic. It misses the downtown areas of every major town in South Central Ohio, but has a major share of the business in the area, being built through adjacent areas that were prime for city expansion in the 1950s and 1960s.
Logan Subdivision (161.295 MHz):
The Logan Subdivision is the former C&O/Hocking Valley line from Athens to Columbus. The CSX Athens Industrial Track runs from Groveport Pike at Parsons Yard to Groveport; the I&O takes over at Groveport. The line still has quite a bit of business, especially at Lancaster (Ralston Foods and Anchor-Hocking Glass) and Logan.
Midland Subdivision (161.220 MHz):
The Midland Subdivision is the former B&O main line between Columbus and Miland City, where is joined with the B&O Parkersburg-Cincinnati main. Sold to I&O in October 2004, the line has it's operating center at Washington Court House in Fayette County. Several locals are based here, and the junction with the DT&I Subdivision is here as well.
Columbus District (161.190 MHz):
Built by the Scioto Valley Railway, the Columbus District is the former Norfolk & Western main line between Columbus and Portsmouth. The Columbus District terminated at Joyce Yard in Columbus, adjacent to the Pennsy's Grogan Yard; as N&W was a subsidiary of PRR, most coal traffic from the line was transferred to Grogan Yard for forwarding to Sandusky. Much manifest traffic was generally transferred to other PRR yards in the Columbus area for forwarding to other parts of the PRR system. Traffic was also interchanged with other railroads in Columbus.
Columbus District operations in Columbus are centered at Watkins Yard. Watkins has diminished considerably in importance since the CSX/Conrail/NS merger in 1999, but still hosts some locals as well as interchange with CSX Parsons Yard. Adjacent to Watkins is Discovery Park, the primary NS intermodal facility in the area; it is due to be replaced in the next year or so by a new, larger intermodal facility just south of Valley Crossing and adjacent to Rickenbacker International Airport, a large freight hub.