The Monongahela Incline, or Mon Incline, is the oldest continuously operating funicular railway in the United States. It opened May 28, 1870 and continues to operate on a daily basis. On a typical weekday, it carries 1,500 riders, and that number nearly doubles on Saturdays and holidays. In recent years, the Mon Incline had become subject to an increase in unplanned service outages. Often times during service outages, the Port Authority of Allegheny County arranged to have shuttles available to ensure customers would not miss their transportation to work, as the Incline provides a critical link between residential areas of Mt. Washington and the Downtown Central Business District.
Numerous intermittent problems were contributing to the Incline’s issues. Diagnostics were further complicated when a variety of problems were being reported in one general drive fault in the PLC. Whenever this general fault registered, the PLC was programmed to shut the Incline down. Some of the problems included in this general drive fault involved limit switches, air temperature changes, tach problems, and changes in pressure for the air operated components.