Hennepin County and the city of Minneapolis released this press release Friday. In short, a preliminary report suggests that wind is to blame for the failure of two cable connections on the Martin Olav Sabo pedestrian and biking bridge in Minneapolis. The bridge was closed from Feb. 19 to June 1.
June 8, 2012 (MINNEAPOLIS) Minneapolis and Hennepin County Public Works staff this morning received a project summary from the engineering firm hired to investigate why the cable connections fractured. The full report with technical details and data will be available June 28; however the project summary provides the firm’s conclusions that wind-induced cable vibrations caused fatigue cracking in the diaphragm plates resulting in two cable connections fracturing.
Wiss, Janney, Elstner Associates, Inc. is an engineering firm with specialized expertise in determining the cause of structural issues in bridges and designing appropriate repair solutions. The firm was hired specifically to investigate why the cable connections fractured and identify options for a permanent solution to repair the bridge.
The City of Minneapolis and Hennepin County have begun discussions with URS, the bridge designer about these findings. The City, County, Wiss, Janney, Elstner and URS continue to work cooperatively in a responsible manner to develop permanent retrofit solutions.
To receive a copy of the project summary or to arrange for an interview this afternoon (between 1 – 3 p.m.) with City, County and Wiss, Janney, Elstner staff, please contact Casper Hill at 612-432-5749.
The Sabo Bridge is a 215 foot-long cable-stayed suspension bridge that opened in November of 2007 to carry bicycles and pedestrians on the Midtown Greenway over Hiawatha Avenue and the Hiawatha Light Rail line. On Sunday, Feb. 19, pair of suspension cable connections fractured. The bridge was closed for further evaluation, support structures were put in place under a portion of the bridge deck, and other work was done. The bridge reopened to bike and pedestrian traffic on June 1, after engineers determined the bridge could safely be reopened before permanent repairs are made. The bridge’s redundant design performed as expected to support the bridge when the pair of cables broke loose.