I doublechecked the map, and Graniteville is on their line from Augusta, GA to Columbia, SC. Probably not enough traffic to economically justify signalling the line would be my guess (I used to work for the NS, but not down south), though after the lawsuits they may end up putting in switch-alignment indicators (which won't help with broken rails or a bridge out, but to be fair, the railroads aren't really earning their cost of capital these days, yet are swamped with new traffic that requires capacity expansion.)
Speaking of signals, the best I ever heard of were color position lights, where instead of just the normal red, amber, green they also were duplicated with 3 lights in a row: green vertical, amber diagonal, and red horizontal. Much safer and easier to determine from a distance, but I guess they cost too much, because I understand they are being phased-out and replace with the standard 'traffic light'-type signals.
Sometimes, even as a conservative, I question how effective the FRA is with their safety oversight.
TWC with no CTC islands. Scary.