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Potomac Yard in Alexandria, Virginia — The American South (Mid-Atlantic)
 

The Rail Yard Hump

City of Alexandria Est. 1749

 

— Potomac Yard —

 
The Rail Yard Hump Marker image. Click for full size.
By Devry Jones, March 30, 2018
1. The Rail Yard Hump Marker
Inscription.  Certain rail classification yards depended on a simple landform called the "hump." Potomac Yard had two humps: one for the northbound trains and one for the southbound trains. Trains first entered a receiving yard where locomotives were detached from trains and cars were sent to a classification yard over the hump: a hill built between the two yards. After being pushed to the top of the hump by a yard locomotive, cars were uncoupled in specific groups and allowed to roll down one of several different tracks to become part of a new train. This group of tracks formed the classification yard. This system used gravity—and a good deal of pre-planning by track managers—to make classifying (or sorting) rail cars much easier.

Technological Advances
Potomac Yard incorporated numerous technological advances over the years to improve efficiency. Classifying cars evolved from primarily manual labor to utilizing automated and digital systems. Computers, installed at the Yard in the 1960s and 1970s, replaced mechanical relay systems with state-of-the-art digital systems.

The first hump yards at Potomac Yard were
The Rail Yard Hump Marker image. Click for full size.
By Devry Jones, March 30, 2018
2. The Rail Yard Hump Marker
operated manually by car-cutters who uncoupled the cars when they reached the top of the hump. Switch tenders lined the switches and brakemen rode the cars down the hill and slowed their descent using hand-operated brakes. In the 1930s and 1940s, remotely-operated switches and car retarders were installed and controlled from two towers on each hump.

In the late 1950s, the hump yards were once again updated when the VELAC system was installed at the southbound hump. VELAC, an automated classification yard system, replaced remote switches with electronic switches controlled from a four-story concrete tower. Touted as an "electronic brain," VELAC made car classification even more efficient and required fewer employees.
 
Erected by City of Alexandria.
 
Topics and series. This historical marker is listed in these topic lists: Railroads & StreetcarsScience & Medicine. In addition, it is included in the Virginia, The City of Alexandria series list.
 
Location. 38° 49.355′ N, 77° 2.913′ W. Marker is in Potomac Yard in Alexandria, Virginia. Marker is at the intersection of Main Line Boulevard and Potomac Avenue, on the right when traveling north on Main Line Boulevard. Touch for map. Marker is at or near this postal address: 650 Potomac Avenue, Alexandria VA 22301, United States of America. Touch for directions.
 
Other nearby markers. At least 8 other markers
Nearby sign at Potomac Yard Park image. Click for full size.
By Devry Jones, March 30, 2018
3. Nearby sign at Potomac Yard Park
are within walking distance of this marker. Crossroads of Transportation (within shouting distance of this marker); Potomac Yard in Transition (within shouting distance of this marker); The People of Potomac Yard (approx. ¼ mile away); The Alexandria Almshouse (approx. 0.3 miles away); Building Potomac Yard (approx. half a mile away); Potomac Town Hall and Firehouse (approx. half a mile away); Corporal Charles William Hill (approx. half a mile away); Smoot Lumber Company Planing Mill (approx. 0.6 miles away). Touch for a list and map of all markers in Potomac Yard.
 
 
Credits. This page was last revised on April 17, 2020. It was originally submitted on March 30, 2018, by Devry Becker Jones of Washington, District of Columbia. This page has been viewed 103 times since then and 16 times this year. Photos:   1, 2, 3. submitted on March 30, 2018, by Devry Becker Jones of Washington, District of Columbia. • Bernard Fisher was the editor who published this page.
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Aug. 10, 2020