Recycling on the Mississippi

Patnaik, Jacob; ,

Recycling on the Mississippi

by Jacob Patnaik, Chief; Bridge Engineering Branch, U.S. Coast Guard, Washington, DC,

Serial Information: Civil Engineering—ASCE, 1993, Vol. 63, Issue 2, Pg. 64-65

Document Type: Feature article

Abstract:

Changes in the Mississippi River's water depth and alignment are forcing the retirement of the 105-year-old Hannibal, Mo. swing bridge. Although the bridge's twin navigation openings of 159 ft, with a closed position vertical clearance of 20 ft had once been adequate, the swing span and its pivot pier, pose an obstruction and safety hazard to passing barges and boats. The bridge's owner, Norfolk Southern Railroad, Atlanta, came up with a novel, and cheaper, way to replace the bridge. Why not barge in another bridge owned by Norfolk Southern; the unused 400 ft span vertical lift bridge in Florence, Ala. that crosses the Tennessee River? This switch would save about $1 million in construction costs and at least 12 months of construction time. Engineers at the U.S. Coast Guard figured out the details for the span-for-span alteration, which has proceeded in two phases. Under a $3.7 million contract, construction of a new substructure and a control house that involved the building of three new piers, the modification of one abutment, and the construction of a 54 ft dolphin and a new control/operator's house. The superstructure, Florence lift bridge, was dismantled and refurbished under a $9.3 million contract.

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