The next landmark on the railroad past Pigpen Siding was Horseshoe Curve, a sharp curve in the shape of a horseshoe near the adjacent treeline, which was fashioned after the Pennsylvania Railroad's Horseshoe Curve near Altoona, Pennsylvania, and which restricted trains to 8 mph (13 km/hr). After leaving Horseshoe Curve, a second, lesser-used, siding was encountered, after which the line curved to the right and the Long Fill (about a five-foot (1.7 m) fill) where the best speed on the railroad could be made. (Although trains were restricted in revenue service to 12 mph (19 km/hr), locomotive #1500, ironically the least powerful locomotive on the railroad's roster, was known to have attained in excess of 40 mph (64 km/hr) on numerous occasions. However, the lack of a long straight (tangent) track, and the risk of turning over a rail, were concerns that limited "high speed" running on the C&S RR.)