Railroads & Locomotives Railroad Operations Horseshoe Curve

Horseshoe Curve

By Lucas Iverson | October 27, 2024

170 years of history for this engineering marvel that attracts millions to this day

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Black-and-white locomotives on Penn Central history freight train curving through mountains
A westbound Penn Central freight rounds Horseshoe Curve west of Altoona, Pa., on May 30, 1969, on Track 4. Trailing unit 3536, a former Pennsylvania Railroad F7B, is unusual here. J. David Ingles photo

 

Mention the name, “horseshoe curve,” and your mind will immediately think of the World Famous Horseshoe Curve nestled deep in the Allegheny Mountains west of Altoona, Penn. That shouldn’t be a surprise considering this landmark’s history and engineering marvel that’s been attracting visitors for 170 years, ranging from the curious to the most enthusiastic.

 

When the Philadelphia-Pittsburgh Pennsylvania Railroad looked to connect Harrisburg in the early 1950s, what stood between the fledgling railroad and westward expansion was the Allegheny Mountains. While the Gallitzin Tunnels was one solution to traverse the rugged terrain standing tall at 2,161 feet above sea level, another was a horseshoe-style curve to help ease the gradient, which would reach a maximum of roughly 2.5% along the entire route.

 

Pennsy chief engineer J. Edgar Thomson headed the project. The set location for the curve at Kittanning Point was the result of a dozen passage options being surveyed. The four-year slog to carve through the Alleghenies was made possible by the hard work of Irish immigrants hired by the Pennsylvania Railroad. The Horseshoe Curve, and ultimately the new Pittsburgh-Harrisburg main line, opened on February 15, 1854. From there grew a legendary railroad that would stretch well into the U.S. history books beyond its eventual 10,000-mile network.

 

When completed, the curve became renowned as one of the eight engineering marvels of the world. It resides between 1,500 and 1,900 feet of elevation with a modest incline of 1.45% heading west. While the original routing and alignment remains the same, the line has been a primary candidate for improvements and expansion over the years. Block signals were introduced in 1875, followed by automatic block signaling in 1900. While the original double-track main line was triple-tracked in 1898, and then quadruple-tracked in 1900 — though track No. 2 would eventually be removed in 1981 by PRR successor Conrail.

 

Children watch along a fence as a freight train passes
Baldwin Centipede locomotive 5827 and an unseen mate shove hard against the class N5c cabin car as yet another in the parade of westbound Pennsylvania Railroad freights challenges the Allegheny Mountains at Horseshoe Curve west of Altoona. Frank Quin photo

 

It wasn’t long until Horseshoe Curve caught the attention of many wishing to witness this marvel and its scenic beauty. The Pennsylvania Railroad didn’t shy away from promotional opportunities upon completing significant landscaping to the area in 1879. The completion of a macadam road in 1932 also became a game changer as it provided easier access to the curve.

 

The inside of the loop eventually set the stage for a park-like destination as tourism to the area increased at the end of World War II. Over the years, the site has seen additions and improvements for the visitor’s experience, including a gift shop in 1940 and multiple pieces of displayed equipment with Altoona-built K4-class 4-6-2 No. 1361 as the most prominent. A significant addition came in the form of a $5.8 million visitor center that was supported by both the state and the National Park Service. Completed in 1992, the facility includes a funicular to complement the 10-story stairway for viewing the curve at track level. The overall site is managed today by the Altoona’s Railroaders Memorial Museum.

 

The curve, itself, remains active and serves as a vital connection in modern-day railroading, even with its designation as a National Historic Landmark since 1967. After the Pennsylvania Railroad days in 1968, the landmark has seen three additional owners: Penn Central, 1968-1976; Conrail, 1976-1999; and currently, Norfolk Southern Corp. Today, roughly 50-70 trains of both NS and Amtrak traverse what is now the Pittsburgh Line with the passenger rail carrier’s New York-Pittsburgh Pennsylvanian making a station stop in Altoona.

 

The late Trains and Classic Trains Senior Editor J. David Ingles and his friend Dick Wallin visited the World Famous Horseshoe Curve in 1969.

 

Black and white locomotives round a curve people in the foreground wave to the crew
A westbound Norfolk Southern stack train, led by ES44AC unit No. 8122 and C44-9W unit No. 8992, climbs Horseshoe Curve at Milepost PT 242, five miles west of Altoona, Pa.., on NS’s Pittsburgh Line, on May 27, 2013. Dan Cupper

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