Caption of drawing at top left The GE P42DC produced by General Electric Transportation Systems.Caption of drawing at top right Norfolk Southern SD40-Es usually come up in pairs. And often on both ends of long freight trains going up hill. (Up is to your left as you face the track.)Caption of drawing at center left Truck trailers were first carried on flat cars in 1927. Today with the advent of doublestack trailers and containers, the railroad has been able to move more goods more efficiently than ever before.Caption of drawing at center right Amtrak got its own fleet of lightweight passenger cars in the mid-1970's, the first major order (492 units) for intercity passenger cars since the WWII era. Budd Manufacturing Company supplied the Amfleet cars in red, white and blue livery and configured to Amcoach, Amcafe, Amlounge or Amdinette functions.Caption of drawing at bottom left Entire trains of coal hoppers are a common sight on the Curve. You will see mostly empty cars going upgrade, loaded cars going down. Most of the coal mines are west of here and the typical markets are northeastern power companies.Caption of drawing at bottom right Overhead clearances were established in the early days. For example, the 17 to 18 foot heights of the tunnels at Gallitzin can keep some loads off of this route. But some large loads can be shipped by using a depressed center or "semi-well" flat car.Text in Center Box FACTS AND FIGURESHorseshoe Curve measures 2375 feet from the beginning to the end of its curvature.The lower end of the Curve is 1594 feet above sea level, the upper end is 1716 feet. (That's a difference of 122 feet.)The diameter of the half-circle formed by the Curve is 1300 feet. In engineering terms, the degree of curvature is 9 degrees, 25 minutes.The average grade is 91 feet per mile. That is also 1.8% or 1.8 foot rise for every 100 feet of run. At the center of the Curve the grade is reduced slightly to compensate for the increased friction of the curved track.The Curve was opened on February 15, 1854. And two tracks were in operation by the end of that year. In 1898 a third track was addedc and in late 1899 to early 1900 a fourth. Conrail removed the second from inside track in 1981 due to a decline in traffic.Horseshoe Curve has been in continuous use since it opened, with few exceptions: Strikes have briefly halted operations and there have been weather-related closures such as those resulting from the Johnstown floods of 1889 and 1977.An average day's traffic is 60 trains in both directions, not counting returning helpers. For comparison in 1904 (a high point) there were 168 trains per day.