Many rumors have circulated regarding the "re-farming" of the railroad radio band and whether or not people will be able to monitor it once the changes are made. First of all, don't worry... These changes will progress very slowly. There isn't going to be a point where everything changes in a day, or even a month. It will take years before the whole rail system adopts a totally new standard. Once it does, you will still be able to monitor it. The way you monitor it may change, but it will still be open.

The reason for these changes are the various mandates that the FCC has imposed for radio systems... Their overall goal is to reorganize the radio spectrum so there's more room for all of the wireless equipment being put into use today, and to also try and create more interoperability between various services. One of the ways they're creating more space, is by narrowing the channel spacing in different service bands by splitting them...

The original AAR railroad radio band has a spacing of 25 kHz for it's channels. Modern technology allows channels to be spaced much closer together now, which creates more channels in a much smaller amount of radio spectrum. The FCC mandates that new radio systems go from 25 kHz channels to smaller 12.5 kHz channels by 2013 (step spacing will go from 15 kHz to 7.5 kHz). They also want new radio systems to eventually be capable of an even smaller channel spacing, mandating that manufacturers make all new equipment capable of a 6.25 kHz channel by 2011, and that end users of new systems use a 6.25 kHz channel by 2018 (time not set in stone). The new railroad band plan with the first 12.5 kHz mandate by 2013 does not require radios to be digital. However, due to technical limitations for the much tighter 6.25 kHz channel spacing that will eventually happen, the 6.25 kHz plan will require radios to be digital. It's this second new plan due around 2018 that has railroads experimenting with digital and trying to decide how exactly they will go about the change. Most new radios being purchased now are capable of both analog and digital, or they're at least capable of being modified to digital. Recently the FCC has recommended that the rail industry skip over the 2013 mandate altogether and just start shooting for the 6.25 kHz standard. Some of the larger railroads have decided to start working on this by replacing radios with new models capable of doing both analog and 6.25 kHz digital. This however does NOT mean things are going digital anytime soon... It just means they're starting to replace equipment. Remember, all radios in a large area have to be capable of the new protocol before it can be used, including track-side transmitter sites. This takes a lot of time and money.

What will digital mean? For now it's hard to say exactly how it will all work. There is talk of trunking and other possibilities in the new plan. The most important thing to emphasize though, is that this will be a very slow change, and it will most likely NOT include any encryption on normal voice channels. Early on, the APCO-25 or 'P25' protocol was being tested for use as the standard in the rail industry. However, Motorola has indicated that they don't seem to have much interest in the railroad industry at this point, due to the fact that they've discontinued both the railroad Spectra and Astro Spectra radio models. It now appears that the standard digital protocol for railroad radio will probably end up being the new Kenwood / Icom format called NXDN (Sometimes referred to as IDAS by Icom). This protocol is proprietary to Kenwood and Icom equipment. It's also cheaper to implement than P25. Having a proprietary digital protocol for the rail industry wouldn't be that much of a problem, because unlike civil services, the rail industry is fairly self contained... They don't need their system to be compatible with other services. It's been reported that the big roads have been starting to replace mobile radios with NXDN capable radios. As of 2008-2009, some of the new radio equipment being fielded by the large roads is as follows:

Norfolk Southern: Kenwood TK-290 portables, unknown mobiles.
CSX: Icom portables, Motorola mobiles and Kenwood portables.
BNSF: Kenwood TK-290 & TK-2180 portables, some Motorolas, Kenwood TK-790 & 740 mobiles. 
UPRR: Kenwood TK-290 & TK-2180 portables.
P&W, MBTA & Amtrak (nationwide): Icom F5061 mobile and the F3161 portable.

Motorola no longer produces a dedicated 'clean cab' railroad radio, such as the Spectra or Astro Spectra. Motorola does have the P25 capable XTL2500 and XTL5000 mobiles, but these are not dedicated 'clean cab' style radios. There's basically three known 'clean cab' style radios other than the old Motorolas, and they're produced by JEM (Kenwood/Icom electronics), Wabtec (refurbished Motorolas), and GE (formerly Harmon).

So what does this mean for railroad monitoring? As radios are replaced with 12.5 kHz and/or 6.25 kHz capable radios, there will probably be some new 12.5 kHz channels slowly popping up... most likely secondary channels used by yards, MoW, PD and so on. It's unlikely the actual road radio systems will be turned upside down, just because new channels are available. Most scanners will still be able to hear the new 12.5 kHz channels. As more equipment is replaced with 6.25 kHz equipment, both in the locomotives and at transmitter sites, it can be surmised that certain sections of lines may slowly start switching from analog to digital. Since the radios will be able to do both, it won't be an issue for crews to switch over while traveling through different areas. But it is very unlikely this will happen anytime soon. The mandate to use 6.26 kHz is years off, and there is no logical reason for the railroads to spend millions of dollars to change all their systems along the entire right-of-way overnight. By the time it does change, there's a chance NXDN may start showing up in scanners. It all depends on how popular the protocol becomes and how much scanner buyers ask for it. So start pestering the scanner companies now. Worse case scenario, you would be able to buy a commercial radio to listen. So the sky isn't falling! Have fun listening.

Below is a table based on the last rail band plan information released by the FCC.