A map of railroads in the Washington, DC area during World War II. B&O Railroad lines are in blue; lines affiliated with the Pennsylvania Railroad are in red, the Southern Railway is in green, and the Washington & Old Dominion Railroad is in pink. Other rail lines are in black. Image by the author.

The second span of Long Bridge, currently under construction, will double rail capacity across the Potomac when it is completed. However, this is not the first attempt to increase capacity by building a second rail crossing of the river in the District.

During World War II, the US Army Corps of Engineers built an “Emergency Bridge” across the Potomac to increase capacity and provide a back-up if Nazi saboteurs damaged or destroyed Long Bridge. Unlike the bridge currently under construction, the Emergency Bridge was not located parallel to the existing bridge; instead, it crossed the Potomac between Blue Plains and Alexandria.

Why build a second Potomac crossing?

The Potomac River has long been a barrier to rail travel along the East Coast. The Baltimore & Ohio (B&O) Railroad opened a railroad bridge across the Potomac at Harpers Ferry in 1837 as part of its east-west main line to the Ohio River. It remained the furthest downstream crossing of the Potomac until the Union Army laid railroad tracks across a predecessor to today’s Long Bridge during the Civil War.

Even after the Civil War, when the District became an important nexus between the Northeast’s rail network and the rebuilt railroads of the Southeast, Long Bridge in its several iterations remained the only rail bridge over the river below Harpers Ferry and the Blue Ridge. When the Pennsylvania Railroad gained exclusive control of Long Bridge for the last quarter of the 19th Century and denied the B&O access, the B&O built its Alexandria Extension to Shepherds Point (on the site of today’s Blue Plains wastewater treatment plant) and ran a ferry across the river to carry freight cars to Alexandria. But it never attempted to built a bridge on the site before it regained access to Long Bridge and discontinued the ferry in 1906.

After the opening of Union Station in 1908, the railroads were satisfied with Long Bridge. But, when the US entered World War II, the federal government decided that a second Potomac River bridge was needed. World War II was perhaps the last war in which the US military was extremely dependent on railroads: As during World War I and the Civil War, the Army activated railroad battalions for duty in the theatres of operations.

Rail was much more essential to moving supplies and soldiers within the continental US in the early 1940s than it is today, and the existence of a single, two-track bridge as a choke point between the Southeast and Northeast was seen as a major issue. Had saboteurs managed to destroy Long Bridge — which carried between 165 and 185 trains daily by the end of the war — it would have seriously disrupted military and civilian logistics until a replacement could be built.

A second-hand bridge

The options for building a second Potomac crossing after Pearl Harbor were limited in two ways. First, the need was seen as extremely urgent. With the nation at war, Long Bridge could be attacked at any time. (Nazi saboteurs did sneak into the US six months after Pearl Harbor, though they were captured before taking action, and I cannot find evidence that Long Bridge was among their targets.)

Second, wartime needs meant that both skilled tradespeople and steel were in short supply. The solution devised by the Army Corps of Engineers, who led the project, was to install a second-hand bridge across the Potomac between an existing industrial rail spur to the Alexandria waterfront at 3rd and North Fairfax Streets and the B&O Alexandria Extension that had led to the former Shepherd’s Point railcar ferry.

The Corps identified a decommissioned bridge over the Saginaw River on the Grand Trunk Western Railroad in Bay City, Michigan, partially disassembled it into seven sections, and shipped it by barge to Alexandria. On November 1, 1942, less than nine months after the decision to build a second Potomac Bridge, the first trains crossed the 3,360-foot Emergency Bridge.

The Emergency Bridge in wartime

The Emergency Bridge was just that: a backup for Long Bridge that saw some traffic, but never diverted a substantial share of Long Bridge’s traffic. There were several reasons for this. First, it was a single-track bridge at the end of a long single-track branch line that required a substantial detour for trains to reach downtown Washington, the B&O’s Metropolitan Branch to the west, or the Pennsylvania Railroad’s line to the Northeast.

Furthermore, although the entire portion of the Alexandria Extension south of its connection to the Baltimore & Potomac Railroad Anacostia Railroad Bridge was upgraded with new rail, switches, signals, and grade crossing protections, using the line posed security complications. The line ran through Bolling Air Force Base and Naval Support Facility Anacostia and wartime security concerns resulted in a requirement that armed guards accompany every train along the line to prevent unauthorized entry. Trains also had to yield to frequent aircraft take-offs and landings at the military airfields.

Another difficulty with using the Emergency Bridge was that, unlike Long Bridge, it was located downstream of the Anacostia River’s waterfront and naval facilities, and was not elevated enough for ships to pass under it. To allow for river traffic, the bridge’s central drawbridge portion was kept open except when it was in use.

During the war, the bridge averaged three to seven trains daily, with its maximum traffic in October 1944, when 184 trains crossed the bridge in one month — a figure within the range of trains crossing Long Bridge daily in 1945. Both freight and troop trains used the bridge, but no civilian passenger trains, which would likely have posed greater security issues for the military facilities along the line. Traffic was limited to northbound trains due to the constraints of the single-track bridge and line, though emergency plans (that were never activated) would have allowed for bidirectional traffic if Long Bridge was unavailable.

The end of the Emergency Bridge

The Emergency Bridge was a wartime measure that was never intended to be permanent, and the bridge was built quickly using wooden pilings rather than more-secure steel and concrete. Once the war was over, the bridge was withdrawn from service on November 14, 1945, just three years after it opened, and it was demolished in early 1947.

Today, the industrial rail spur that led to the Virginia approach to the bridge is owned by Norfolk Southern Railway, and is inactive. The portion of the Alexandria Extension south of the Baltimore & Potomac Railroad Anacostia Railroad Bridge was abandoned due to post-September 11 security concerns. Its last remaining user moved weekly chlorine gas deliveries to the Blue Plains wastewater treatment plant.

Related post-September 11 security concerns about the passage of rail freight through downtown Washington, and through the Virginia Avenue Tunnel, with its western portal just blocks from the Capitol, led the National Capital Planning Commission to perform a study on detouring freight around Washington in 2007.

Of the three proposals the study found to be feasible, one involved a two-track tunnel under the Potomac between Long Bridge and the former Emergency Bridge. The other two would have used the CSX Pope’s Creek subdivision, which separates from the Northeast Corridor in Bowie, to connect to a new rail bridge across the Potomac well south of Washington, to be built either near Quantico or near the US Route 301 bridge to Dalgren. However, nothing came of these proposals, and with CSX’s 2015-2018 rebuilding of the Virginia Avenue Tunnel to handle double-stacked freight, it is probable that freight trains through Washington will continue to use Long Bridge for a long time to come.

Source notes

I’d like to thank Marina Reilly-Collette of the US Army Corps of Engineers Portland District for initially bringing the history of Emergency Bridge to my attention. While the history of the Emergency Bridge across the Potomac is not well-known, I found two articles about the bridge that provided useful sources for this article:

• Bertsch, Amy and Mallamo, Lance. “A Temporary Bridge Across the Potomac.” Alexandria Times. 9 February 2017.
• Kenton, Malcolm. “A Wartime Lesson in Infrastructure Resiliency.” Trains. 30 January 2019.

In addition, the Emergency Bridge is mentioned in the virginiaplaces.org page on the transportation network of Alexandria and the National Railway Historical Society’s D.C. Chapter’s timeline of Washington, DC railroad history. The January 1946 issue of Railroad Magazine also evidently contained an article about the Emergency Bridge, but I have not been able to acquire a copy of it.