The Thomas Viaduct spans the Patapsco River and its valley between Relay and Elkridge, MD. It was commissioned by the B&O Railroad; built between July 4, 1833, and July 4, 1835; and named for Philip E. Thomas, the company’s first president. It remains the world’s oldest multiple arched stone railroad bridge.
At its completion, this viaduct was the largest railroad bridge in the United States and the country’s first multi-span masonry rail bridge to be built on a curve. It is divided into eight spans and was designed by Benjamin Henry Latrobe II, who was then B&O’s assistant engineer and later its chief engineer. In 1964, it was designated as a National Historic Landmark. In 2010, the bridge was designated as a National Historic Civil Engineering Landmark by the American Society of Civil Engineers.
Thomas Viaduct is now owned and operated by CSX Transportation (successor to the B&O) and still is in daily operation, making it one of the oldest railroad bridges still in service.
The viaduct’s span is 612 feet; individual arches are roughly 58 feet in span, with a height of 59 feet from water level to the base of the rail. Width at the top is 26 feet 4 inches. The bridge is constructed using a rough-dressed Maryland granite ashlar, known as Woodstock granite, from Patapsco River quarries. A wooden-floored walkway built for pedestrian and railway employee use is 4 ft. wide and supported by cast iron brackets and edged with ornamental cast iron railings. The viaduct contains 24,476 cubic yards of masonry and cost $142,236.51, equal to $3,568,301 today.
In 1835 the Washington Branch was constructed, including the Thomas Viaduct. This branch was at Relay, MD, the site of a former hotel and changing point for stagecoach horses. The 1830s Relay House served as a hotel until it was replaced by the $50,078.41 (equal to $1,081,833 today) Viaduct Hotel in 1872. The Gothic combination railroad station and hotel operated until 1938 and was torn down in 1950.
When the Thomas Viaduct was completed, a 15-foot obelisk bearing names of the builder, directors of the railroad, the architect and others associated with the viaduct was erected at the east end in Relay, by builder John McCartney. On one side the monument read: The Thomas Viaduct, Commenced July 4, 1833 Finished, July 4, 1835. He also celebrated the completed work by having his men kneel on the deck of the viaduct while mock “baptizing” them with a pint of whiskey.
Until after the Civil War, the B&O was the only railroad into Washington, DC. Thus, the Thomas Viaduct was essential for supply trains to reach the nation’s capital during that conflict. To prevent sabotage, the bridge was heavily guarded by Union troops stationed along its length.
In 1929, extensive mortar work on the masonry was carried out, and again in 1937. To counteract deterioration, the Thomas Viaduct underwent more cosmetic upgrades in 1938, performed by the B&O. The viaduct is still indicative of the way in which B&O track and major structures were constructed – built to last! At an unknown date, railing blocks were removed from the north side of the deck and a bracketed walkway added giving more lateral clearance.
From the 1880s to the 1950s, Thomas Viaduct carried B&O’s famed Royal Blue line passenger trains between New York and Washington. Until the late 1960s, the bridge also carried B&O passenger trains traveling to points west of Washington, such as the Capital Limited and National Limited, both westbound. With the advent of Amtrak on May 1, 1971, B&O ended its passenger train service, except for local Baltimore–Washington commuter trains. In 1986, CSX acquired the B&O and all of its trackage, including the Thomas Viaduct.
The bridge was designated a National Historic Landmark on January 28, 1964, and administratively listed on the National Register of Historic Places on October 15, 1966. In 2010, the bridge designated as a National Historic Civil Engineering Landmark by the American Society of Civil Engineers.
Yours truly has been over this landmark a number of times as a passenger, as well as having “looked up from ground level at its beauty.” It definitely is awe-inspiring…but so sad that they tore down the old hotel…it would have been a finishing touch to the scene!