With early summer storm brewing in the area, the sound of thunder continues to roll down the steel rails as NS 129 (Chattanooga,TN-Birmingham,AL) roll down the AGS North-End just four miles south of the Tennessee, and Georgia State line. Its mind blowing to this day that this secondary line is still using track authority. To the old timer that once work on the railroad and the older generation of railfans track authority was use in the old DTC system which to surprise is still being use today. In DTC, controlled tracks and sidings (those requiring authority from the train dispatcher to occupy) are divided into pre-specified blocks. In addition to being listed by milepost in the railroad's timetable, block limits are delineated by conspicuous signs along the tracks. Every portion of controlled track belongs to a block, as blocks are laid out back-to-back along the entire length of the rail line. Just a little different from CTC, and old compare to the new PTC system.
