English: The 1839 survey of the en:Tapeworm Railroad route (top) with excavations (tracks weren't completed) included a switchback from en:Maria Furnace westward along the en:Nichols Gap Road. The route was to loop west of the location where the Nichols Gap Road crossed Toms Creek in a topographic gap between ~900 ft (270 m) levels (bottom). The survey map shows the 3 crossing points of the route, the road, and the creek (white pixels at top, with misaligned hachures to the northeast) were at 3 distinctly different points. At the easternmost of the 3 points, the railroad company built a single-arch stone bridge for the road over the creek. (The roadway bridge is often misidentified as being for the railway and--with the inaccurate term "viaduct"--as having multiple arches.) In addition to the never-built Tapeworm Railroad trestle to cross the gap west of the roadway bridge, a Tapeworm Railroad tunnel was planned nearby (top, outlined) through a spur of Jacks Mountain. In 1888-1889, the "Western Extension" was built by the en:Baltimore and Harrisburg Railway (bottom) east of the gap, crossing Toms Creek at a lower elevation than the original Tapeworm Railroad route.