|
The Smithfield Street Bridge, built in 1881-1883, is Pittsburgh's oldest surviving river bridge, entering its 128th year of service in 2010. It's unique design and stunning longevity have made it a Pittsburgh treasure as well as a national monument. Despite it's age, the Smithfield Street Bridge remains one of the city's main arteries connecting the northern and southern shores of the Monongahela River. In addition to high automobile and transit use, the pedestrian walkway is a vital link between the Golden Triangle and the many attractions across the waterway at the Station Square complex. The present structure is actually the third rendition of the bridge. The first, a covered wooden span known as the Monongahela Bridge, was built in 1818 by Louis Wernwag at a cost of $102,000. The bridge was seriously damaged in 1832 by a runaway boat. After extensive repairs, it stood for another thirteen years before burning during the Great Fire of 1845.
In 1846, a replacement span was constructed and renamed the Smithfield Street Bridge. It was a wire rope suspension bridge built by John Roebling, the legendary engineer who went on to build the Brooklyn Bridge. It was Roebling's first highway bridge. Unfortunately, increases in vehicular traffic soon made the eight short spans that made up the structure obsolete. A larger, more durable alternative was needed.
The Roebling span was dismantled in 1881 in favor of the current bridge with a unique and revolutionary design. The new bridge was designed by another legendary engineer, Gustav Lindenthal. It used the standing stone piers that remained from the Roebling structure and was built with future expansion in mind. The bridge was opened to traffic on March 19, 1883.
Since its initial dedication in 1883, the landmark span has undergone four major modifications. In 1891, a third truss was added, doubling the bridge width to accomodate increases in vehicular and trolley traffic. The bridge was further widened in 1911 when the north and south portals were redesigned. In 1934, the bridge deck was replaced. Finally, in 1994-1995, the bridge underwent a thorough rehabilitation. The trademark trolley tracks were removed and the bridge's road surface restructured for three vehicle lanes. The structural steel was reinforced and a colorful paint scheme applied. These modifications ensure that the venerable Smithfield Street Bridge will remain in operation well into the 21st century.
In addition to being Pittsburgh's oldest river bridge, the heavily traveled span is the oldest steel through-truss bridge in America, and the only one in this country employing the over-and-under double lenticular truss design. The bridge has been designated a National Historic Civic Engineering Landmark.
|
