Description:

Replacing the Aging US 52 Mississippi River Bridge 

Abstract

The US 52 bridge over the Mississippi River in Savanna, Illinois was originally constructed in 1932. It provides a crucial transportation link for the region, connecting Savanna, Illinois to Sabula, Iowa with the nearest alternate Mississippi River crossing located almost 20 miles to the south in Fulton, Illinois.  Over the years, a number of repairs had been made to the bridge and it was rapidly approaching the end of its useful life and in need of replacement.

The new replacement bridge consists of 12 spans totaling 2454 ft from a causeway in the middle of the Upper Mississippi River Wildlife and Fish Refuge in the Mississippi River on the Iowa side to the high bluffs of the Mississippi Palisades in Illinois.  A 546 ft main span steel tied-arch over the navigation channel flanked by steel girder approach spans was designed by Parsons Corporation in coordination with the Illinois DOT with construction completed and opened to traffic in November 2017.  

Challenging aspects of the project included minimizing environmental impacts, designing around varying geotechnical conditions and a relatively deep river pool, and coordinating with various agencies including a railroad line.  The influence of the structure depth on the vertical profile along with constructability and maintenance concerns led to the selection of a main span steel tied-arch with floating deck system.   The large water depth and varying rock elevations led to the desire to limit deep cofferdams in favor of waterline footings with drilled shafts.