The PRR's Horseshoe Curve

Throughout the years there were many horseshoe-like projects carried out on America's railroads in an attempt to keep a particular line's ruling grade at a manageable level. However, none became as famous as the Pennsylvania Railroad's Horseshoe Curve. It was credited as an engineering marvel in the mid-19th century when it was constructed and was so well planned and designed that it remains in regular use today, as an important main line artery between the east coast and Chicago. Railfans have become enamored by the location, not only because of its unique design but also because of the number of trains that traverse the curve on a daily basis.

Entire libraries could be written on the Pennsylvania Railroad ranging from its history to the different businesses it owned, far, far too much to cover here which is a mere brief history of the railroad. The Pennsy was an institution to the City of Philadelphia and State of Pennsylvania. For over 100 years the keystone represented the PRR as much as it did the State of Pennsylvania itself. The PRR had been in existence for just under ten years when it reached the area around Altoona, Pennsylvania in the south-central region of the state. Thus far during the company's construction it had been able to keep its ruling grade to no greater than 1.8% by hugging river valleys whenever possible such as the Juniata and Susquehanna.

Altoona, and the area west of the city (both of which sat at the foot of the Allegheny Mountains) became a real challenge as the topography made it extremely difficult to keep the ruling grade at or under 1.8%, as required by top management. To solve the dilemma the Pennsylvania Railroad's chief engineer, John Edgar Thomson in the late 1840s looked to improve a survey that had been done by Colonel Charles Schlatter in 1839. Thomson's new idea was to head south through Altoona using the Juniata River valley then turn west hugging the foothills of the mountain range.

To reach the other hillside and keep the grade under 1.8% Thomson opted to fill in the valley floor between the hills, which crossed two small creeks (Kittanning Run and Burgoon's Run). This created an almost perfect horseshoe and once on the western hill the line then headed due east for a short distance before turning south and then back west, all of the while hugging the hillsides as much as possible (it should also be noted that roughly six miles west of the curve is the location of Gallitizin Tunnel).

What became known as Horseshoe Curve began construction in the early 1850s and was officially opened on February 15, 1854. While the route initially only featured one track it grew to four around the turn of the 20th century not only because of the PRR's fast and low-grade route between New York and Chicago but also because the railroad's primary locomotive and maintenance shops were located right nearby in Altoona.  Today, the curve features only three tracks with the loss of significant passenger train traffic (Conrail removed the fourth track soon after its startup in 1976). However, today the line remains as busy as ever, usually hosting more than 50 Norfolk Southern freight trains and a few Amtrak passenger trains every day.  To read more about the Pennsylvania Railroad please click here.

As early as 1879 a park dedicated to the engineering marvel has been located in the bowl of the curve. In 1932 an access road was completed to the park and in 1957 the Pennsylvania Railroad dedicated a retired Class K4 Pacific steam locomotive (#1361) to be featured at the park. In 1986 the curve was adorned with the rare status as a National Historic Landmark and in the late 1980s the National Park Service became involved by permanently helping to maintain the park's facilities and overall grounds. Today, the park is part of the nearby Altoona Rail Roaders Memorial Museum (which preserves the PRR's massive shop complex located in the city) and sees thousands of visitors and tourists each year.  To learn more about visiting the curve please click here.

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