Before the Conrail merger in 1999 CSX used Direct traffic control on all of its unsignaled lines. DTC makes use of fixed blocks with movement authority provided from the dispatcher to the train directly via radio communications (hence the D in DTC). This was in contrast to previous systems where trains would follow a predetermined timetable and any changes would have to be given to crews via block operators or lineside telephones (aka Indirect Traffic Control). When Conrail trritory was incorporated those lines used the Form D Control System or DCS. This was similar to DTC it referenced stations and interlockings as valid block limits (with a block limit sign being a form of station), but don't let the D in DCS fool you as DCS is a Track Warrant system, not a DTC system.
|Say Goodbye to old CSX DTC Block Signs Like These|