Norfolk Southern Bridge DH-514.47 is a span drive vertical lift bridge that carries one track of rail across the Mississippi River in Hannibal, Missouri. The lift span truss is 417'-0" long and 20'-6" wide with a 41'-4" lift height and weighs 3 million pounds. The bridge was erected in 1959 in Florence, Alabama, but was relocated to its present location in 1992. In September 2011, Norfolk Southern initiated a work order to investigate the source of poor and erratic operating behavior that the bridge exhibited. This presentation will discuss this project from the owners, engineers and contractor's viewpoint. Areas of focus will include: the specific inspection tasks which lead to the identification of excessive system friction resultant from severe abrasive wear at the trunnion journals, the rehabilitation design plans prepared to facilitate the trunnion repair as well as to address the root cause of the deterioration, coordination necessary to obtain the necessary marine and rail traffic outages to perform the work, and the challenges faced during the implementation of the field work under frigid conditions in the winter of 2014. The presentation will close with an assessment of the success of the rehabilitation work through an evaluation of the operating loads both prior to and following the repair work. This paper and presentation will be of particular interest to movable bridge owners, engineers, maintainers and inspectors as it will present significant findings that may be used to consider what benefits may be achieved through a properly executed repair.
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