|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.
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
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.