The narrow band channel steps on VHF public safety and business channels are 7.5 kHz so that's what you set your scanner for to program the channels. The bandwidth of the signal is nominally 12.5 kHz.
The railroads, like all public safety and business users, are under an FCC mandate to switch to narrowband by January 1, 2013. CSX in my area seems to have switched, except for a couple of Avon Yard base stations which are very loud compared to everybody else on the channel. There have been reports in this forum of the UP and other railroads switching to narrowband. So, it doesn't surprise me that you are hearing the CN using narrowband.
I'm looking forward to this new change over.
Its already done in your area
The craggy Mountain lines in asheville nc. will soon need radio. I plane on getting kenwood radios and program them to our frequencies, But would we have to go to the digital system too in 2025ish? Were a small historical line non for profit?
I doubt you would be required to use the AAR plan given your isolation. However, if you ever need to communicate with NS, you would be unable to do so.
Don't know where you got the June 1, 2018?
Again, railroads have been researching it, including buying the NXDN capable radios, but, there are no plans for the conversion in the forseeable future.