Collapse of Lake Street/Marshall Avenue Bridge	Print    Inquire    847-965-7500

Problem
The Lake Street/Marshall Avenue Bridge consists of two reinforced concrete arches, each spanning approximately 550 ft, across the Mississippi River between Minneapolis and St. Paul. Construction of the east arch required the use of falsework with a clear span of 200 ft to maintain the navigation channel of the Mississippi. This section of falsework, consisting of four post-tensioned steel trusses supported on steel towers, collapsed during construction of the concrete arch, killing one worker.

Next Steps
CTLGroup was retained by the Minnesota Department of Transportation to investigate the collapse. CTLGroup recovered falsework members from the river and developed a metallurgical test program for key structural components.

Results
The investigation included detailed inspection and testing of the recovered falsework members, interviews of various eyewitnesses to the accident, review of design documents, review of field construction records and construction photographs, and review of contract specifications. A detailed finite element model of the falsework was also constructed to establish the collapse sequence and cause of the collapse. CTLGroup also provided technical support in the subsequent litigation.