The Pennsylvania Railroad’s Wilmore track pan installation, the largest ever built, was a fine example of the public works that running a railroad entailed. Located on the western slope of the Alleghenies near the PRR’s Pittsburgh Division milepost no. 260.8, Wilmore was the scene of both heavy freight and fast passenger traffic. By the early 1940s, its four track pans were each 2685 feet—the world’s longest.

Constructed on a tangent (straight track section), the entire length had been carefully engineered to be perfectly flat to keep the water level even. Each pan was 26 inches wide with a four-inch lip overhanging inward to reduce splashing. Pan depth was seven inches except on Track 1 which used 152-pound rail and pan depth was increased to eight inches to better enable Mountain class locomotives to scoop water. Pan sections were made of steel and were welded together. Replacement sections were stored nearby to replace damaged pans as needed. Periodic welding and repairs were necessary when the pans were damaged by scoops or developed leaks.

Water was supplied by gravity through a 20-inch pipe with 20 pounds of pressure from a nearby mountain reservoir that was created by the PRR when it built the Wilmore Dam. As early as 1929, this installation was using 1.5 million gallons a day. The added demands during World War II made it necessary to supplement the water supply by municipal service at 85 lb pressure from nearby Benns Creek. After the war, a water treatment plant was added to reduce boiler corrosion.

Water level in the pans was measured by an indicator or equalization pipe, one per pan, located at the midpoint of

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the pan. This pipe led to a valve house in which a 14-inch round tank housed a float that in turn controlled a pilot valve to the main 10-inch valve in the pit below. Water was admitted through the four-inch supply lines that ran underground, through the undertrack tunnels, and up to the pans.

There the supply line pipes were joined via a flexible hose that allowed for expansion/contraction to a four-inch elbow which fed water through openings in the sides of the pans. With ten filling points on each pan admitting water at right angles to the pan length, splash was contained by the four-inch overhanging lip. (At other installations, water was fed in through the bottom of the pan or through the side in an angled fashion, or from behind deflector plates.) There were three valve houses at Wilmore, one opposite the boiler plant and the other two a thousand feet in each direction.

At times, small fish from the reservoir found their way into the pans, sometime jamming the water level floats, which caused the pans to overflow. The pans had to be cleaned periodically to remove dead fish, coal, and other debris.

To protect the trackbed from erosion by water splashed during scooping, thousands of Belgian blocks were laid beside the tracks and a series of drains installed. The Wilmore installation contained ten tunnels at right angles to and under the right of way. The first and last of these were within ten feet of the pan ends and the rest spaced about 300 feet apart. These tunnels, which carried off drainage and housed the water supply and indicator lines, were of four-foot-diameter bolted cast iron sections.

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