An Engineering Marvel-Horseshoe Curve


Nestled deep in the Alleghenies lies an engineering marvel, the Horseshoe Curve. Completed by the Pennsylvania Railroad in 1854, it successfully created a rail passage through the rugged terrain of the Alleghenies.

Prior to the construction of the curve, transportation across Pennsylvania was a time consuming and tedious process. Wagon loads of travelers would brave the elements and rough terrain for over 20 days to get to the their destination. In 1834, the Allegheny Portage Railroad was completed and began operations. This cut the travel time down to four days, whether traveling by ship, rail, or wagon. The Allegheny Portage Railroad provided a passage through the Alleghenies, bypassing the most treacherous part of the entire journey.

With the creation of the Horseshoe Curve, the travel time was reduced to just 15 hours, making it a substantial engineering accomplishment. The curve was engineered by J. Edgar Thompson, and was completed using over 400 workers. The curve was built using hand tools, as no machinery was used, making working conditions difficult and dangerous.

The curve tackled the steep incline of the Alleghenies at a 1.8% grade, this was a significant improvement over the previous grade of 6% used by the Allegheny Portage Railroad. Horseshoe curve is comprised of two curves, a northern curve and a southern curve. The northern curve measures in at a radius of 637 feet, and the southern curve measures at 609 feet.

Other than the PRR, other railroads operated the curve after the PRR merged with the New York Central in 1968, forming the Penn Central, which operated the curve until 1976. At this time, Conrail was formed and controlled the curve until the merger in 1998-1999, and it became Norfolk Southern, which operates it today.

Building the Curve

Charles McCain

J. Edgar Thompson, who eventually became the president of the Pennsylvania Railroad, raised funds for the Horseshoe Curve project. Thompson was the engineer responsible for the creation of the curve and designated that it be built west of Altoona, increasing the grade gradually, where it eventually rose 122 ft. Edgar was focused on the ease of operation and efficiency of the trains that had to tackle the curve, as he wanted trains to be able to cross easily with the assistance of a helper engine. The work was challenging as laborers had to break away parts of the mountain, only with the use of picks and shovels. Workers used dynamite to cut out large portions of the mountain, then built and evened out the foundation for the curve.

Early plans for a passage through the Alleghenies included a tunnel that would have to be 3,600 feet long. This would require removing large sections of the mountain and moving copious amounts of land. This plan did not come to fruition because of the PRRs lack of funds, and wanted to settle with the Allegheny Portage Railroad as the sole passage through the mountain. As an engineer, J. Edgar Thomson adopted a plan to find a different route, as he did not want the PRR to be dependent on the Allegheny Portage Railroad, which was plagued with delays, and did not operate at night. Thomson fought with the board of directors for funding for the project, and to stay competitive with the Baltimore and Ohio, and the New York and Erie. He was repeatedly denied and took it upon himself to advertise the project in local newspapers and bulletins during stockholder meetings. He was successful in his plight, as he was later elected as the PRR’s president, and gained overwhelming support for his project, as stockholders supported his plan, the final vote cast was 134,680 votes for the plan, and 754 votes against it.

“World Famous Horseshoe Curve” Griff Teller

Although Thomson’s plan was supported and he had the go ahead to start the project, building the curve was sure to be an provocative task. The grade of the railroad increased from some 800 ft from Harrisburg, the capital of Pennsylvania, to Altoona, which is a total distance of approximately 132 miles. From Altoona, to the crest of the mountain located in Gallitzin, the railroad had to increase the gradient 1000 feet in the short stretch of 12 miles.

To conquer this massive feat, he decided on one of two options. The first option was to approach the Alleghenies in a straight line. The second, which was ultimately chosen, was to detour the tracks for a mile or more through a nearby valley, then to a knob called Kittanning Point, and then continuing into another curve,creating the horseshoe like shape. In order to complete this project, a tunnel had to be built at the crest of the mountain at Gallitzin. This was a dangerous task as workers were dangerously close to a cliff, and had to use dynamite to blast out part of the mountain.

On February 15, 1854, the curve was finally completed giving travelers a direct passage through the Allegheny mountains. This linked the entire state of Pennsylvania, from Philadelphia to Pittsburgh.

Within due time, the fascination with Horseshoe Curve began and it was soon a sought after location for rail enthusiasts, as in 1880, a park was built in the middle of the curve for this very purpose.

The curve was originally two tracks but was widened to three tracks in the late 1800s, however, traffic was increasing at an astounding rate, as the railroads were beginning to make their mark on the country, and the curve was eventually widened to four tracks in 1900.

Timothy E. Pavlic II

For years to come, Horseshoe Curve became an attraction. When a PRR passenger train passed through the curve, the conductor would notify the passengers. The Horseshoe Curve was on one of the busiest rail lines in the country, which at its peak saw close to 120 trains daily. Today, over 50 trains use the curve daily, making it one of the most sought after spots for rail enthusiasts worldwide.

When visiting Horseshoe Curve today you will be greeted with the sight of a PRR GP9 locomotive in the center of the park. To get to the curve, visitors can either take the steps or catch a ride on the “Funicular”, which is a inclined railroad on a track leading up to the curve powered by cables.

While visiting Horseshoe Curve, be sure to visit the Railroader’s Memorial Museum, located just a short drive from the curve. The museum is dedicated to remembering the sacrifices and contributions of railroaders throughout the years. It focuses on the significance of the infrastructure around Altoona its significant contribution to the nation’s infrastructure, especially during the industrial revolution.

When visiting the curve today, visitors will have the opportunity to see Norfolk Southern and Amtrak trains, as well as many sets of helper units used to push freight trains over the mountain.


Visiting Horseshoe Curve

Horseshoe Curve Park Hours of Operation

Monday-Saturday: 9am-6pm

Sunday: 11am-6pm


2400 Veterans Memorial Highway

Altoona, PA 16601


$8 for Horseshoe Curve

$11 for combined Horseshoe Curve Park and Railroader’s Memorial Museum.


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