US 421, Milton-Madison Bridge over the Ohio River

American Structurepoint provided construction inspection services on the US 421 bridge over the Ohio River project, which included bridge pier rehabilitation and construction of a new superstructure, new approach piers, abutments, approaches, retaining walls, and a pedestrian bridge. The design-build project began in Kentucky at the intersection of KY 36 and US 421 going to the intersection of Fillmore Street and US 421 in Indiana for a total length of 0.696 mile. The length of the new bridge from the center of the south abutment to the center of the north abutment is 3,117 feet. The bridge has 12 spans, with four of those 12 being a steel truss bridge located in the center portion of the bridge structure over the Ohio River.

The bridge was constructed with 40 feet of clear roadway plus a 5-foot sidewalk going across the bridge and has a 90-feet minimum navigational clearance above the river. During the construction of the US 421 bridge over the Ohio River, temporary bridge supports were constructed adjacent to the existing bridge. The permanent superstructure deck was constructed on these temporary supports, and once the permanent piers were constructed and strengthened with high-performance concrete, the new deck was moved over and positioned on the permanent piers. During this process, traffic was allowed to continue on the existing bridge until the new deck was ready. Traffic used the temporary bridge location until the old bridge was prepared for the new deck. The total planned time for the bridge to be closed to traffic was 10 days. A temporary and/or emergency ferry service was provided as necessary during any total bridge closure periods. Work was performed as a sub to Michael Baker, Jr., in conjunction with the Indiana Department of Transportation Seymour District. Approximate construction costs were $103 million.