Acrow Delivers Temporary Bridge to Windy City

The Windy City needed a new bridge in a hurry.

The Chicago Department of Transportation (CDOT) selected F.H. Paschen, S.N. Nielsen & Associates in June 2014 for an emergency $6 million replacement of the Division Street Bridge over the Chicago River North Branch Canal. The job came with a tight three-month deadline and involved demolition of the existing 111-year-old trunnion bascule bridge, removal of the bridge’s drivetrains and counterweights, and elimination of the existing abutments.

From an engineering perspective, the project posed a number of challenges: first, vertical clearance had to match the existing bridge; second, the sloped site profile required a unique method of getting the structure in place; and third, the fabrication of specialty components. Additionally, CDOT required source inspection of the Acrow fabrication facility in Milton, Pennsylvania, and certification that all components were manufactured in the United States, plus other quality assurances. In 2006, Acrow provided a temporary bridge for Chicago’s North Avenue.

acrow2The Acrow 700XS panel bridge was selected as the interim span for Division Street based on availability, quick delivery and speed of erection. Acrow’s engineering team worked with the CDOT’s bridge team and the contractor to develop a solution based on readily available prefabricated bridge elements.

The bridge selected was comprised of three simple, independent spans of 60 feet, 140 feet, and 60 feet. The structure has a roadway width of 36 feet with two five-foot walkways cantilevered off of each side of the bridge. To minimize the dead load and to expedite construction, an orthotropic deck with an anti-skid aggregate epoxy coating applied to the roadway surface was used for driving safety and to eliminate the need for asphalt.

The bridge was assembled on rollers behind the east abutment and rolled across the river using a cantilevered launch over the east river pier to the west river pier. The launch was carefully orchestrated to compensate for the upward arching of the steel, which was used to create the proper clearance from the top of the water and the sloped site profile. Once the main span was in place over the reconstructed piers, it was jacked up off the rollers and lowered onto the bearings. Once all three spans were on bearings, the roadway deck panels, the two pedestrian walkways and guiderail system were installed.

Traffic was reopened across the bridge ahead of schedule in September 2014. The quick work resulted in F.H. Paschen, S.N. Nielson & Associates being recognized as the “Outstanding Bridge Contractor of the Year” by CDOT.

The city is currently doing engineering work and identifying funding sources for a permanent replacement on Division Street. A CDOT spokesman said that project could take up to five years to complete. But now there’s some time to spare. Acrow says the 700XS panel bridge can be used as a permanent structure with an anticipated lifespan of 75 to 100 years.


Information for this article was provided by Acrow Bridge and edited by ARTBA’s Mark Holan.

Photos Courtesy of Acrow Bridge


 

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