Phase I: Swing Span Replacement
Ames Construction (Minneapolis, MN) was awarded phase I, which included the removal and replacement of an existing 360 foot swing span with a new vertical lift span. The process involved building two new piers and placing 140-foot towers around the existing bridge. The center pivot pier was then removed to open the navigation span to 350 feet. (The old swing span was listed as the worst bridge on the Mississippi River for collisions.) During construction, train (approx 30 a day) and tugboat traffic (approx 12 a day) had to be maintained and uninterrupted.
The new lift span truss was built on 4 barges just downstream of the existing bridge. The new truss weighs about 5 million pounds and dimensionally is 370 feet long, 65 feet tall and 36 feet wide. Ames Construction working with the local crafts had only 30 hrs to float out the old swing span and float in the new trust span and have the tracks cleared for traffic. This is a Truman Hobbs project, which meant it was partially funded by the Coast Guard through BNSF.
Phase II: Replacement of Abutment Structures
Walsh Construction (Chicago, IL) was awarded phase II of the BNSF bridge project which involved replacement of the 7 approach spans connecting to the new lift span crossing the Mississippi River. In working with the local crafts, Walsh constructed 6 spans approx. 10 miles downstream by Wever, IA and floated the spans upstream to their final location in Burlington. This project involved drilled shaft foundations over 150’ deep into the river bottom to hold the new bridge structures and similar to phase one, Walsh was allowed only 24 – 36 hour windows in which the old spans were removed and the new ones floated in and tracks cleared for rail traffic.