Daniel Webster Hoan Bridge
Additional Resources:
Failure Analysis Full Report (3 MB PDF)
Failure Analysis Summary (HTML)
In-Depth Inspection Report (5 MB PDF)
Client
State of Wisconsin
Dept. of Transportation
Wisconsin Department of Transportation
Project
A 200+ ft. long, three girder span fails and sags 4 feet.  The span is part of a nearly two mile long, six lane bridge/viaduct structure which carries  I-794 into downtown Milwaukee, Wisconsin.  More than 36,000 vehicles use the bridge each day.
Scope of Work
Emergency inspection and analysis of bridge failure.  Emergency retrofit to re-open bridge to traffic.  Replacement of failed span and permanent retrofit of entire structure to avoid similar failures in the future.
Construction Cost
$7,800,000
Explosive demolition of damaged span
Explosive demolition of damaged span










Hoan Bridge main arch span
Project Details
The Daniel Webster Hoan Bridge is a 1.9 mile structure composed of a three span, 1140 foot long tied steel arch, 18 spans of continuous steel girders and numerous steel girder approach spans over the Milwaukee River.  It was constructed in 1977 and carries three lanes of traffic in each direction.  A vital link serving the downtown Milwaukee area, the bridge carries more than 36,000 vehicles per day.

On December 13, 2000 with temperatures hovering below zero degrees, a major crack was discovered in a steel girder in the northbound span just south of the arch.  The approach spans are composed of three longitudinal girders spaced 24.5 ft. apart.  The northbound and southbound superstructures are independent but share a common pier.   The crack originated at a shelf plate that connected horizontal wind bracing to the web of the girders.  The span sagged about 4 feet and was immediately closed to all traffic.

Lichtenstein was immediately mobilized by the Wisconsin Department of Transportation to conduct an emergency inspection of all the spans to determine whether there were additional cracks.  As the failed span was on the northbound approach, a determination needed to be made whether the southbound spans could be opened to limited traffic.  Lichtenstein was also charged with the task of conducting a failure analysis that included metal testing, strain gauging, and fracture and fractographic analysis to determine the cause of cracking.  All of these tasks were conducted on an accelerated basis including removal of the damaged span by explosive demolition.

Additional cracks of a less severe nature were found originating at the same detail at other locations.  A retrofit was designed and constructed and the southbound lanes were opened to two directional vehicular traffic on February 17, 2001.

Contract plans, specifications and estimates were developed for retrofit and reconstruction of the demolished span in accordance with recommendations of the failure investigation and retrofit study.  The $7.8 million fast-track permanent retrofit of all three-girder spans on the bridge and replacement of the demolished span was completed in October, 2001.

The project team received the FHWA Strive for Excellence Award in 2001 for its efforts on this project.

 

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