10. Sleeper stones
During the construction of the Allegheny Portage Railroad, cost considerations drove much of the initial system. Huge amounts of granite and other rock were unearthed, some of it going to line the canal beds and walls. Other uses of granite, which was in abundance, proved less successful. One such use was placing granite stones as the foundation of the rail beds, supporting the weight of the trains as they passed along the rails. Granite stones, known as sleepers were cut and placed beneath the iron rails. They proved unsatisfactory. Water permeated the stones and caused them to split from the weight and vibration of the trains. They also demonstrated a tendency to move, leaving sections of rail unsupported.
When the railroad opened nearly its entire length rode on granite sleeper stones, cut from the walls of the mountain. By 1840 most had been replaced with wooden ties. The wood both supported and cushioned the rails, and replacing them as necessary was easier for maintenance crews. The technology of using wooden ties was adopted by other railways in the United States, including the Baltimore and Ohio, then pushing west toward Harpers Ferry in Virginia, and the Pennsylvania Railroad. The stone sleepers found other uses, including being broken up for stone fences and walls, and building construction. The gaps left where they were cut from the mountainsides can still be seen throughout much of central Pennsylvania.