Bridge Safety:

Structural Soundness of the Zilwaukee Bridge

RCED-88-96: Published: Mar 29, 1988. Publicly Released: Apr 12, 1988.

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In response to a congressional request, GAO reviewed the Zilwaukee Bridge Project to: (1) determine whether the testing program that the Michigan Department of Transportation (MDOT) implemented confirmed that the bridge was structurally sound; (2) identify construction problems causing concerns about the bridge and determine whether they would affect its ability to perform as designed; and (3) assess the MDOT draft bridge maintenance manual.

GAO found that: (1) the tests indicated that the Zilwaukee Bridge had performed as designed and that the concrete exceeded design requirements for strength and durability; (2) repairs made after a 1982 construction accident fully restored the damaged areas of the bridge; (3) concrete spalling and cracking did not affect the bridge's ability to perform as designed; (4) MDOT took corrective action to ensure proper bonding of all areas with a concrete overlay; and (5) although an independent panel's review of the maintenance manual concluded that the manual was generally well prepared, it recommended several changes that, if followed, would provide for more adequate future maintenance.

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