I have been surveying bridges on the railroad for about a month now for UPRR. We are required to have a flagmen present and a radio with us at all times but the railroad does not always have enough radios to give the flagmen so I said I could program one of my radios to work. Does the railroad use a repeater system? I am guessing they are on VHF from what I have seen in the database, if they do not use a repeater system is it simplex and then transmitted over the phone lines or how does it work?