Over the River
In the early years, overland traffic simply forded the river; in 1777, a ferry was established. The first bridge was built sometime after 1800, carrying the turnpike that would eventually become Washington Boulevard, part of the present-day U.S. Route 1.
When the Baltimore & Ohio Railroad came up river it shadowed the route of the turnpike, and encountered the same natural wall of hills. From Relay, across the Patapsco from Elkridge, the main westward stem of the B&O continued right up the river gorge for five miles, reaching Ellicott City in 1830. (The earliest trains were horse-drawn; Relay earned its name as the place where tired horses were exchanged for fresh ones.) A second rail line, bound for the nation's capital, had to cross the river. And that's how the still-standing Thomas Viaduct came to be built in the 1830s, a marvel of engineering that has withstood heavy locomotive traffic, the grumbles of naysayers, and the threat of war.
Crossing the Patapsco by rail brought a number of new problems for the bridge builders. Trains were neither as light nor as flexible as horse-drawn wagons. A rail bridge would have to be strong, roughly level with the tracks on both banks of the river, and high above the stream. More daunting, it would have to curve to the left in order to steer clear of the beetling bluffs on the far bank, but the curve had to be gradual to accommodate the large turning circle required by trains. Nobody had ever built a bridge quite like it before.
To design this unprecedented structure, the B&O tapped Benjamin Latrobe Jr., son and namesake of the Baltimore architect famed for his work on the U.S. Capitol. The younger Latrobe, still in his mid-20s, had neither studied engineering formally nor designed a bridge; he'd been trained as a lawyer. Apparently, though, he impressed B&O officials; he proved to have something of his father's gifts and, as it turns out, amazing foresight to boot.
Latrobe designed a span of nine arches upheld by eight tall piers in addition to the abutments on either end. To achieve the necessary curve, the piers were laid out along the radii of an enormous arc. Although it's not obvious to present-day observers, the piers are slightly wedge-shaped when viewed in cross-section. This design kept the spaces between them rectangular, simplifying the construction of the arches.
According to the historical marker at the entrance to Patapsco Valley State Park, skeptics hooted at the project: "'Ridiculous!' 'Impossible!' Such were the stern pronouncements in 1833 as work began on the world's oldest, multiple-arched stone railroad bridge." Edward Hangerford's 1928 book The Story of the Baltimore & Ohio Railroad confirms that "for some years the bridge was called, by idle-minded folk, 'Latrobe's Folly.' This name was taken up for a time by engineers who swore that the bridge could not even be built, that it would not stand under its own weight."
The mockery is understandable, especially considering the architect's lack of experience. For its time, the bridge was a huge undertaking, 700 feet long and rising 66 feet over the riverbed. Although it was conceived as neat geometry, it was built with thousands of rough-hewn, irregular granite blocks the size of refrigerators. Several workers died during construction, and others were badly injured.
But Latrobe's construction of the bridge, dubbed the Thomas Viaduct (after Philip Thomas, first president of the B&O), was completed in two years--officially, from July 4, 1833, to July 4, 1835. It has been in continuous use ever since. Even the Civil War failed to halt traffic across the viaduct, thanks to a Union Army garrison at Relay. Most remarkably, for a structure built at a time when locomotives weighed six tons, this old bridge routinely carries diesel engines 50 times that weight. Together, the two crossings at Elkridge--the railroad and Washington Boulevard--handled more than half the traffic between Baltimore and Washington for more than a century.
The man who directed the building of the bridge, John McCartney of Ohio, was so proud of it that he erected, at his own expense, a commemorative obelisk that still stands at the north end of the bridge. McCartney's monument is engraved with the names of contemporary B&O directors as well as the technical team in charge. The officials listed include many names that still resound in Baltimore's cityscape: Patterson, Oliver, McKim, Swan, Ellicott, and Alexander Brown.
These days, it's easier to see the viaduct than to reach it. Traveling north on Interstate 95, glance to the right after passing the Harbor Tunnel (895) exit; going west on 895, look to the right--and down--after the Washington Boulevard exit. Sadly, this landmark looks small and dingy from the perspective of the freeways that fly past it. To see Latrobe's handiwork up close, take Washington Boulevard to South Street in Relay, between the ramps for Routes 895 and 195. Off South Street, take the entrance to Patapsco Valley State Park, which leads directly to the Thomas Viaduct. In contrast to this dignified old structure, the I-95 overpass--a short drive up the same road--looks like the work of heartless aliens.
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