Horseshoe Curve (Pennsylvania) - Location and Design

Location and Design

Horseshoe Curve is a 3,485-foot (1,062 m) segment of the Pittsburgh Line, the Norfolk Southern Railway's main east–west route in its Pittsburgh Division between Pittsburgh and Harrisburg, Pennsylvania. Trains heading west from Altoona have to ascend a maximum grade of 1.85 percent for 12 miles (19 km) to the summit of the Allegheny Mountains in Gallitzin. From there, trains traverse the Gallitzin Tunnels and descend for 25 miles (40 km), at a maximum grade of 1.05 percent, into Johnstown.

The curve is located 5 miles (8 km) west of Altoona in Logan Township, Blair County at railroad milepost 242. The Blair County Veterans Memorial Highway (SR 4008) parallels the valley west from Altoona and crosses under the curve via a tunnel. Within the open eastern end of Horseshoe Curve is a dam and lake, the highest of a series of three reservoirs along the valley which are owned by the Altoona Water Authority and supply water to the city. Horseshoe Curve spans two ravines formed by creeks: Kittanning Run on the northern side, and Glenwhite Run on the southern.

For every 100 feet (30 m), the tracks at Horseshoe Curve bend 9 degrees and 15 minutes with the entire curve totaling 220 degrees. At its widest, the curve is approximately 1,300 feet (400 m) across. Horseshoe Curve descends from an elevation of 1,650 feet (500 m) on the southern side to 1,594 feet (486 m) on the northern with a grade of 1.73 percent. Three sets of 140-pound-per-yard (70 kg/m), continuous welded railroad tracks make up the curve. Prior to dieselization and the introduction of dynamic braking and rail oilers, the rails along the curve would be transposed—left to right and vice versa—to equalize the amount of wear on one side of the rail from the flanges of passing steam locomotives and rail cars, extending their lifespan.