Horseshoe Curve (Pennsylvania)

Horseshoe Curve
U.S. National Register of Historic Places
U.S. National Historic Landmark
An orthophoto of Horseshoe Curve. Trains headed counterclockwise around the curve are ascending.
Location:	Logan Township, Blair County, Pennsylvania
Nearest city:	Altoona, Pennsylvania
Coordinates:	40°29′51.5″N 78°29′3″W
Built:	1851–1854
Architect:	John Edgar Thomson, Pennsylvania Railroad
Governing body:	Norfolk Southern Railway
NRHP Reference#:	66000647
Significant dates
Added to NRHP:	November 13, 1966
Designated NHL:	November 13, 1966

Horseshoe Curve is a famous railroad horseshoe curve in central Pennsylvania, near Altoona in the United States. Called an "engineering marvel", it was completed in 1854 by the Pennsylvania Railroad. It was later used by the Penn Central, then Conrail, and is currently owned and operated by the Norfolk Southern Railway.

The Curve is in Kittanning Gap near the summit of the Allegheny Front, about 5 miles (8 km) west of Altoona. It covers about 220 degrees of arc; on the north side, the radius measures 637 ft (194 m), tightening to 609 ft (186 m) on the south side. The elevation at the east end is 1594 feet (486 m) above sea level, rising to 1716 feet (522 m) at the west end.

Design

Horseshoe Curve is a 2,375-foot (724 m) segment of the Pittsburgh Line, the Norfolk Southern Railway's main east–west route between Pittsburgh, Pennsylvania and Harrisburg, Pennsylvania. The curve is located 5 miles (8 km) west of Altoona in Logan Township, Blair County. The Blair County Veterans Memorial Highway (SR 4008) parallels the valley west from Altoona and crosses under the curve via a tunnel. The Altoona Water Authority's Kittanning Reservoir is located within Horseshoe Curve and supplies water for the city of Altoona.

Horseshoe Curve has 9 degrees and 15 minutes of curvature and a central angle of 220 degrees. At its widest, the curve is approximately 1,300 feet (400 m) across. Horseshoe Curve descends at rate of 91 feet per mile (17 m/km) from an elevation of 1,716 feet (523 m) on the southern side to 1,594 feet (486 m) on the northern. Three sets of 140-pound-per-yard (69 kg/m), continuous welded railroad tracks make up the curve. Prior to dieselization and the introduction of dynamic braking, 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 locomotives and rail cars thereby extending its lifespan.

History

In 1834, the state of Pennsylvania constructed the Allegheny Portage Railroad across the Allegheny Mountains to connect Philadelphia and Pittsburgh. The Portage Railroad consisted of a series of canals and inclined planes and remained in use until the mid-1800s. The Pennsylvania Railroad was incorporated in 1847 and was tasked with building a railroad from Harrisburg to Pittsburgh, bypassing the cumbersome Portage Railroad.

Construction and sabotage

Using surveys done several earlier, the state's engineers recommended a route from Lewistown that followed the ridges, keeping the maximum grade over the entire 84-mile (135 km) line at 0.852 percent. The Chief Engineer for the Pennsylvania Railroad John Edgar Thomson, however, opted to construct a line from Lewistown following lower, flatter terrain along the Juniata River and having the steep grades only on a 9.8-mile (15.8 km) stretch of track west of Altoona. It was discovered that the valley west of Altoona was split into two ravines by a mountain. Surveys done east from the Gallitzin Tunnel at the summit had already determined a suitable route on the opposite side of the valley that would keep the grade at 1.73 percent. Traversing the valley using a bridge would have created a grade of 4.37 percent, which was too steep for most trains. To reduce the grade by the increasing the distance between the points, engineers constructed an earth fill over the first ravine, cutting the point of the mountain, and another fill over the second ravine.

The curve took three years to complete and was constructed without heavy equipment, using only men "with picks and shovels, horses and drags". The entire line, including Horseshoe Curve, was opened on February 15, 1854. The total cost to lay the 31.1 miles (50.1 km) of track between Altoona and Johnstown was $2,495,000 or equivalent to $80,225 per mile ($49,850 /km). The remaining part of the mountain inside the curve was leveled in 1879 to allow for the construction of a park and observation area—the first specifically built for viewing trains. A third set of tracks was added to the curve in 1898 and a fourth was added two years later. From around the 1860s to just before World War II, Horseshoe Curve was served by the Kittanning Point station. A macadam road to the curve was opened in 1932 allowing access for visitors, and a gift shop was constructed in 1940.

During the war, Horseshoe Curve became an important lifeline for the Allied war effort and, subsequently, was placed under armed guard. The military intelligence arm of Nazi Germany, the Abwehr, plotted to sabotage important industrial assets in the United States in a project code-named Operation Pastorius. In June 1942, four men were brought by submarine and landed on the coast of Long Island. They were tasked with destroying such sites as the curve, the Hell Gate Bridge, Alcoa aluminum factories and the locks on the Ohio River. The would-be saboteurs were eventually apprehended by the Federal Bureau of Investigation (FBI) after one, George John Dasch, turned himself in.

Panorama from the outside of the curve in 1934 with the Kittanning Point station in the distance

The curve was designated as a National Historic Landmark in 1966, and is now a part of the National Register of Historic Places.

The location is noted among geologists for its excellent rock outcrops, including the Devonian Catskill Formation.

Current operations

As of 2009, the curve has more than 50 trains daily on the triple-track mainline and it is not uncommon to see three trains passing simultaneously, with long freight trains working the westbound grade assisted by helper engines on the rear. The curve also serves Amtrak's Pennsylvanian, which runs once in each direction every day. It has long been a popular tourist attraction, and is accessible via the Horseshoe Curve Funicular, a funicular railway running to a small park built by the PRR in 1879 at the summit of the ridge. A modern visitors center with a trackside observation area was built in 1992 and is open April through October, managed by the Railroaders Memorial Museum. Altoona's minor league baseball team, the Altoona Curve, is named after this railroad landmark.

Gallery

• 

  Three trains passing on triple-track, July 2006

• 

  Westbound freight grinding upgrade, July 2006

• 

  Eastbound freight rounding the curve, July 2006

• 

  Rock outcrops (Irish Valley Member of Catskill Formation)

See also

• List of Historic Civil Engineering Landmarks
• List of National Historic Landmarks in Pennsylvania
• National Register of Historic Places listings in Cambria County, Pennsylvania
• Tehachapi Loop

Sources

• Cohen, Gary (February 2002). "The Keystone Kommandos". The Atlantic Monthly 289 (2): 46–59. ISSN 1072-7825. http://www.theatlantic.com/past/docs/issues/2002/02/cohen.htm. Retrieved January 31, 2012. 
• Greenwood, Richard (August 9, 1975). "Horseshoe Curve" (PDF). National Register of Historic Places—Nomination Form. National Park Service. http://pdfhost.focus.nps.gov/docs/NHLS/Text/66000647.pdf. Retrieved January 30, 2012. 
• Seidel, David W (2008). Horseshoe Curve. Images of Rail. Charleston, South Carolina: Arcadia Publishing. ISBN 0-7385-5707-2. 

External links

• World Famous Horseshoe Curve (Railroaders Memorial Museum)