Steel in the News
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Posted by Tasha Weiss on December 7, 2012 at 6:13 PM.
A steel network tied arch — the new Amelia Earhart Bridge in Atchison, Kan. — serves as the successor to a 1930s steel truss honoring the famous female flyer. The main arch span length of 527 ft, an economical design not possible with concrete, was necessary due to the heightened potential for scour caused by the older, adjacent bridge and a railroad bridge just upstream. Photo: Mike McPheeters
Many know the story of Amelia Earhart, best known for being the first female to fly solo across the Atlantic Ocean and later attempting a flight around the world at age 40. But likely few know the pioneering pilot was a native of Atchison, Kan., where a bridge named after her flew traffic over the Missouri River for 74 years.
The steel through truss, built as a Works Progress Administration (WPA) project in 1938, had been nursed through nearly 10 rehabilitations before the decision was made to replace it in 2002. Its shoulderless, narrow roadways fell short of 21st century needs. And the condition of its deck trusses worried the owners.
Because the bridge was a beloved, historic structure, both the Kansas and Missouri Departments of Transportation (KDOT and MoDOT) knew the community would have a significant voice in selecting the new design. In fact, citizens already had made one thing clear: The new bridge would be made of steel, like its predecessor.
The new U.S. 59 Amelia Earhart Bridge, a four-lane, ample-shouldered tied-arch bridge, rests just 78 ft south of the old bridge. Approximately 2,546 ft long, the structure consists of 2,019 ft of 78-in. NU (Nebraska University) prestressed concrete I-girder approach spans and a 527-ft steel tied-arch main span.
The new bridge has a 100-year design life and is capable of of handling the 20-year traffic projections of 12,400 vehicles a day — twice the capacity of the previous bridge. The former bridge, kept open to traffic during construction, will be closed once traffic is shifted to the new bridge and will be demolished next year.