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Steel Structure Trivia: Chicago Loop Bridge Turns 50
Posted by Tasha Weiss on October 25, 2013 at 12:01 PM.


Here’s MSC’s October Steel Structure Trivia question! The steel bascule bridge pictured above, as it was being raised during a spring boat run to Lake Michigan, is one of four “modern” (post-1950) bascule bridges in downtown Chicago and celebrates its 50th anniversary on Sunday. (The first movable bridge in the city was also built at this location in 1834.) What is the name of this Chicago Loop bridge? Photo: Courtesy of Jim Phillips



The name of this Chicago Loop bridge is the Dearborn Street Bridge. Congratulations to our winner: Christopher Cichon, a structural associate with Sargent & Lundy in Chicago.


The current bridge at N. Dearborn Street marked 50 years of service last Sunday, October 27.


In 1963, then Mayor Richard J. Daley presided over the ceremony marking the opening of the bridge. According to the Chicago Tribune report of the event, no speeches were given; only a hand signal from the Mayor. The bridge was lowered into place and a procession consisting of a single Cadillac followed by about 20 cyclists crossed the bridge. Seventeen minutes later, regular traffic started flowing across the bridge.


dearborn-street-bridge-plaque.jpgThe steel bascule bridge was a replacement for a Scherzer rolling-lift bascule removed in 1959. The first movable bridge in Chicago was also built at this location in 1834 (see the plaque pictured left which is located on the northeast corner of the present bridge). That bridge was a double-leaf bridge similar to today’s bridge, but with the limitations of technology at the time.


The current Dearborn Street Bridge is the fourth at this location and one of four “modern” (post 1950) bascule bridges in downtown Chicago. These bridges are most easily identified by their single bridgehouse. As with several other downtown bridges, the bridge received a Merit award by AISC when it was completed.


For more information about the Dearborn Street Bridge, contact Jim Phillips (who provided this commentary) at 312.540.0696, or visit his website, which features multimedia pages for all of the Chicago Loop bridges.
You can test your steel structure knowledge right here on our MSC website on the last Friday of each month, where a new photo will be posted to the Steel in the News section as our weekly “Steel Shot.” Your challenge is to correctly answer the trivia question provided in the news post, based on what you see in the photo. The next question will be posted at noon CST on Friday, November 22 (moved up due to the Thanksgiving holiday the following week).



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