http://www.uiuc.edu/ph/www/roma/rr-freqs
Hi Micheal, You can find specific freqs at the site above. N. American railroads have 97 specific channels assigned to them. Some of them use all 97 and some just a few. They're all in the the upper portion of the VHF band so most any scanner will pick them up.
Norfolk Southern
161.115 -- [AAR channel 67] -- EOT devices
161.415 -- [AAR channel 87] -- ex-N&W carmen
160.485 -- [AAR channel 25] -- ex-N&W carmen
161.190 -- [AAR channel 72] -- ex-N&W road (former N&W)
161.250 -- [AAR channel 76] -- ex-N&W road (former Nickel Plate)
160.440 -- [AAR channel 22] -- ex-N&W road (former Wabash)
160.365 -- [AAR channel 17] -- ex-Southern carmen
160.245 -- [AAR channel 09] -- ex-Southern channel 2 (dispatcher-to-train)
160.830 -- [AAR channel 48] -- ex-Southern channel 2 (train-to-dispatcher)
161.490 -- [AAR channel 92] -- ex-Southern channel 3 (yard)
160.770 -- [AAR channel 44] -- ex-Southern channel 4 (road)
160.950 -- [AAR channel 56] -- ex-Southern channel 5 (road)
160.635 -- [AAR channel 35] -- PBX (Manassas, VA)
161.130 -- [AAR channel 68] -- PBX (Tilton, IL-St. Louis, MO)
160.515 -- [AAR channel 27] -- PBX (various points), piggyback ramp (Chicago, IL)
160.620 -- [AAR channel 34] -- police
161.205 -- [AAR channel 73] -- police
160.275 -- [AAR channel 11] -- Salisbury PBX
