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Revision as of 20:01, 13 January 2011 by B137 (talk | contribs)(diff) ← Previous revision | Latest revision (diff) | Newer revision → (diff)Sand Patch Grade is a ~100 mile length of railroad track known for it's steep grades and curves through the Allegany Mountains of Pennsylvania and Maryland. A well known landmark along Sand Patch Grade is the Sand Patch Tunnel, which was constructed in the mid 1800's. The tunnels used vertical ventilation shafts with fires in them to circulate air.