Horseshoe curve

A horseshoe curve is a reversing curve through a single tight curve in a railway or a road, through an angle of about 180 degrees or more. The U shape, or even slight balloon shape, of such a curve resembles a horseshoe, hence the name. On roads such curves, if tight enough, are typically called hairpin turns.

A horseshoe curve is a means to lengthen an ascending or descending grade and thereby reduce the maximum gradient. If the straight route between two points would be too steep to climb, a more circuitous route will increase the distance travelled, allowing the difference in altitude to be averaged over a longer track (or road) length. This is similar to the function of a spiral. However, a horseshoe curve does not involve the track crossing over itself, and the full horseshoe involves both relatively straight and tightly curved sections, while a spiral generally has a more uniform curvature. Obviously, a horseshoe also gives rise to a severe change in direction, while a spiral generally does not.

Horseshoe Curve (disambiguation)

A horseshoe curve is a track layout used to reduce the gradient a train must travel uphill.

Horseshoe Curve may also refer to:

Horseshoe Curve (Pennsylvania)

Horseshoe Curve is a three-track railroad curve on the Norfolk Southern Railway's Pittsburgh Line in Blair County, Pennsylvania. The curve itself is about 2,375-foot (724 m) long and 1,300 feet (400 m) in diameter; it was completed in 1854 by the Pennsylvania Railroad as a way to lessen the grade to the summit of the Allegheny Mountains. It eventually replaced the time-consuming Allegheny Portage Railroad, the only other route across the mountains for large vehicles.

The rail line has been important since its opening, and during World War II the Curve was targeted by Nazi Germany in 1942 as part of Operation Pastorius. The Curve was later owned and used by Pennsylvania Railroad successors Penn Central, Conrail, and Norfolk Southern. Horseshoe Curve was added to the National Register of Historic Places and designated a National Historic Landmark in 1966, and became a National Historic Civil Engineering Landmark in 2004.

Horseshoe Curve has long been a tourist attraction with a trackside observation park being completed in 1879. In the early 1990s the park was renovated and a visitor center built; the Railroaders Memorial Museum in Altoona manages the center, which has exhibits pertaining to the curve.