We knew this day would come as far as a switch from FM to NXDN. The Industry Standard will be NXDN. All of the train frequencies that I listen to in my area all have the emission on the FCC License NXDN even though they still operate FM for now. Just hope the scanners will catch up. DSD will work, having a scanner would be the best option.
Yes, CSX has begun testing NXDN Digital here in INDY. They have not switched over fully yet, but are testing on a couple of the not regularly used channels. From my understanding, they will start doing the yards before switching main roads.