Emergency Closure and Repair of St. Louis’ Jefferson Barracks Bridge

Abstract

The Jefferson Barracks Bridge is a fifteen-span structure that carries I-255 over the Mississippi River, in St. Louis, Missouri. The 910-foot main navigational span consists of a steel tied-arch superstructure, approximately 190 feet tall. In May 2019, during a routine and fracture critical inspection of the main span, inspectors discovered a six-foot crack at the toe of a weld in the steel tie girder. Further investigation revealed that crack extended at least 5/16 inch into the steel web plate. Because the cause of the steel crack was not known and the potential for bridge collapse if the crack were to propagate, the Missouri Department of Transportation (MoDOT) elected to close the three westbound lanes of I-255 on the structure. Several similar cracks were subsequently found at other locations throughout the tie girders. Working together with MoDOT and the Illinois Department of Transportation (IDOT), the inspectors responded quickly to evaluate the extent of the cracking at similar locations, obtain steel core samples, and perform laboratory testing to determine the cause of the steel cracks. Within approximately four days, the team documented the extent of this critical finding, determined the cause, began emergency repairs, and reopened the bridge to limited traffic. This paper/presentation discusses the decisionmaking process for the emergency response and presents the findings from the inspection, the results of the laboratory testing, the cause of the steel cracks, and the approaches used for repair.