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The I-435 Bridge over the Missouri River at Kansas City, Missouri, consists of twin twogirder structures. Inspections by the Missouri Department of Transportation (MoDOT) in 2003 detected numerous cracks at the floor beam and lateral member connections throughout the 30-year-old bridge. An initial evaluation suggested that many of the cracks were the result of distortion-induced stresses. No evidence of unstable crack extension was observed. A comprehensive fatigue study was subsequently carried out to investigate the extent and cause of cracking and to evaluate possible long-term retrofit solutions. Based on the study findings, a retrofit plan was implemented that addressed details susceptible to distortion-induced cracking, end restraint cracking, and crack growth from embedded defects. Large-hole and loosening type retrofits were utilized to reduce the possibility of crack extension. The installed retrofits will significantly extend the remaining fatigue life and facilitate ease of inspection of this critical infrastructure link.

<p>The Maumee River Crossing Project is a large scale concrete bridge project. The contractor chose segmental construction which required the use of four different types of gantries. To assure a consistent design basis, all of the gantries were checked using the governing project engineering standards and project-specific loads. Due to the unique movement capabilities of these launching structures, each construction step from launch to final segment release was examined for each span, and span-specific work methods were developed. In some cases, gantry modifications were required to handle the project demands. In other cases, constraints posed by the supporting structures necessitated the use of structural supplements and customized operational procedures. A physical inspection of all gantries was performed to verify as-build conditions. In addition, quarterly operation audits were carried out to observe launch procedures and conformance of span-specific work methods.</p>