Potomac Yard

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Potomac Yard

site of future Potomac Yard in 1897
Source: US Geological Survey (USGS), Alexandria, VA 1:125,000 topographic quadrangle (1897)`

The Pennsylvania Railroad, the Atlantic Coast Line Railroad, the Southern Railway, the Chesapeake and Ohio Railway, the Seaboard Air Line Railway, and the Baltimore and Ohio Railroad served Alexandria at the start of the 20th Century. To consolidate the five separate passenger terminals in town and create one combined yard to interchange freight cars, the six railroads formed the Richmond-Washington Company in 1901.

the Great Falls and Washington and Old Dominion Railroad (red) crossed Potomac Yard on a trestle, starting in 1906
Source: Library of Congress, Baist's map of the vicinity of Washington D.C (1918)

The passenger terminal opened in 1905. The freight facility, Potomac Yard, opened in 1906.

It was the largest U.S. rail freight classification yard in the United States at the time, covering 450 acres. Trains arrived from the north and south with cars which needed to be delivered to different destinations. Steam-powered locomotives were detached, and cars were rearranged ("switched") into new trains. Cars were classified based on contents and destination, so they could be lined up behind the locomotives in a logical sequence for delivery.

The Mutual Ice Company produced as much as 700 tons of ice daily, which was loaded into cars at Potomac Yard to preserve perishable vegetables, fruit, and other products. That operation continued until refrigerated cars eliminated the need, and the Mutual Ice Company closed in 1969.¹ "127-0172 Main Street Station," National Register of Historic Places nomination form, Virginia Department of Historic Resources, October 15, 1970, https://www.dhr.virginia.gov/historic-registers/127-0172/; "Building Potomac Yard," City of Alexandria, https://www.alexandriava.gov/uploadedFiles/historic/info/archaeology/TrailSignPotomacYardBuilding.pdf (last checked July 16, 2020)

The switching process relied upon gravity, and the topography of the site was altered when the yard was established. An archeological report later concluded that a layer of cinder ballast two feet thick, and in pkaces as much as 15 feet thick, had ben used to help level the ground and:¹ "The Archaeological Investigation of the Former Preston Plantation and Alexandria Canal at Potomac Yard," International Archaeological Consultants, 1996, Public Summary, https://www.alexandriava.gov/uploadedFiles/historic/info/archaeology/SiteReportAdams1996PotomacYardPrestonPlantation.pdf (last checked July 17, 2020

...a significant amount of soil, 11-23 feet had been removed to reduce the knolls or bluff area known from historic records to accommodate the needs of a flat railyard with little or no relief.

Potomac Yard in 1918
Source: Library of Congress, Baist's map of the vicinity of Washington D.C (1918)

Rail cars in an arriving train were hauled up a "hump" or hill built in the yard. At the top, workers known as "car cutters" separated individual cars, and they rolled down the hill towards a network of tracks. Brakemen on top of each car managed the speed. On the ground, Potomac Yard personnel moved track switches in order to send each car onto the desired track.

There was one hump for assembling southbound trains, and a second hump for northbound trains. Often one car at a time, arriving trains were disassembled and new trains were organized to take freight cars to the next destination.

Potomac Yard in 1945
Source: US Geological Survey (USGS), Alexandria, VA 1:31.680 topographic quadrangle (1945)

Over time, the manual procedures were replaced with automated systems. Retarders on the track slowed cars rolling down the hump, reducing the safety risks of brakemen riding on the moving cars. By the 1960's, a few workers in a tower in the middle of the yard could control much of the switching process.¹ "The Rail Yard Hump," City of Alexandria, https://www.alexandriava.gov/uploadedFiles/historic/info/archaeology/TrailSignPotomacYardsRailHump.pdf (last checked July 16, 2020)

Starting in the 1970's, railroads reduced the amount of freight moving through Washington DC. Narrow tunnels, Amtrak passenger trains, and a train collision north of Union Station in 1987 created a chokepoint that delayed delivery. Virginia built an "inland port" at Front Royal in 1989, and it successfully diverted traffic onto the old Shenandoah Valley Railroad route which Norfolk Southern used. The demand for multiple railroads to operate a classification yard dropped, and the facility closed in 1992.¹ "Potomac Yard in Transition," City of Alexandria, https://www.alexandriava.gov/uploadedFiles/historic/info/archaeology/TrailSignPotomacYardsTransition.pdf (last checked July 16, 2020)

Potomac Yard in 2019
Source: US Geological Survey (USGS), Alexandria, VA 1:31.680 topographic quadrangle (2019)