The W Line of the Norfolk Southern Railway is best known for its Saluda Grade, a grueling 4.24% grade ascending into Asheville, North Carolina, representing the steepest grade on an adhesion-based standard gauge railroad in the United States. Formerly the Asheville Subdivision of the Southern Railway, the line was originally opened in 1878 by the Spartanburg and Asheville Railroad in attempt to overcome the Blue Ridge Mountains.
The steepest part of the grade ascends between Melrose and Saluda at a formidable 4.94%. Ascending trains would double and sometimes triple their consists in order to make the climb; ever-present helper operations were also a must. Descending trains encountered two safety tracks along the way. These runaway spurs were originally manned -- the signalman would reverse the switch to the safety track upon hearing specific sequence of whistle blasts from a train descending uncontrollably. Later technology utilized automatic timers -- trains starting their descent after cresting the grade in Saluda would trip a timing circuit that would hold the switch in reverse; the switch would return to normal after a predetermined amount of time. Trains not under controlled braking would reach the switch before time and thus diverge to the safety track.
Today, having succumbed to its operational challenges, Saluda Grade lies dormant. And while tracks and crossbucks remain, it is unlikely that a train will surmount its grade again.