Recycling Bridges

by Jai B. Kim, Prof. & Chmn.; Dept. of Civ. Engrg., Bucknell Univ., Lewisburg, PA 17837,

Serial Information: Civil Engineering—ASCE, 1988, Vol. 58, Issue 11, Pg. 58-59

Document Type: Editorial


Faced with the statistics showing that more than half of our bridges have fallen into a state of disrepair, bridge engineers have coined a phrase from the lexicon of conservationists to describe a new concept in bridge rehabilitation: recycling. By reinforcing the arches of old metal truss bridges, engineers are extending the lives and rejuvenating the structures of bridges that might otherwise have to be replaced. There are approximately 35,000 metal truss bridges in the U.S. and most of them are structurally deficient and load posted. Because the financial resources needed to repair or replace all of these bridges far exceed available funds and also because many of these bridges are historic landmarks, the arch reinforcement method offers a logical, cost effective solution. Engineers have successfully applied the arch reinforcement method to several truss bridges in Connecticut, Idaho, Kentucky, Maryland, New York and Pennsylvania. The method entails superpositioning steel arches on the existing truss and making minor modifications to the substructure to accommodate the arches, from which additional floor beams are hung. These measures strengthen the entire bridge, including its truss and floor system, enabling it to bear up under the weight of heavy traffic loads. The life expectancy of a bridge is extended substantially and the safety of motorists who travel the bridge is enhanced.

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