Steel in the News
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Posted by Tasha Weiss on August 10, 2012 at 2:15 PM.
The 83-year-old, 350-ft-long Checkered House Bridge in Richmond, Vt. was separated 12 feet six inches in just a day and a half. The steel truss bridge was widened to accommodate traffic and enhance safety while maintaining its historical integrity (click on the photo for an enlarged view). Photo: Jared Katz
Vermont’s largest truss bridge, the 350-ft-long Checkered House Bridge on Route 2 in Richmond, was widened in just a day and a half earlier this month. The design-build rehabilitation and widening of the bridge, which was built in 1929, is the first time such a technique has been tried on a bridge of this scale.
After months of preparation, the historic bridge was literally rolled out 12 feet six inches to the north, achieving a launching rate of two feet per hour.
The Checkered House Bridge project is only the second design-build project undertaken by the Vermont Agency of Transportation (VTrans) since design-build project delivery was authorized by the Vermont legislature. They retained Finley Engineering Group, Inc., Harrison & Burrowes Bridge Constructors, Inc., and CHA, Inc., to widen the bridge.
“Widening a bridge of this age, type and size was technically challenging because we needed to consider construction engineering during the design phase,” said Jerry M. Pfuntner, P.E., Finley project manager.
Finley developed and implemented the concept to widen the bridge by cutting and moving the entire North truss chord in place. To maintain the bridge’s historical integrity, the plan was to widen the bridge leaving as many of the original steel members as possible, and installing new structural bracing members within the widened portion of the bridge only. To accomplish this, Finley developed the original concept for a falsework and jacking system that allowed the North truss to be moved while still receiving lateral support from the South truss system.
The South truss was designed to support the entire existing truss bracing members with the aid of this unique falsework system that stabilized the eccentric self-weight, wind loading and jacking forces through the many phases of the North truss jacking operation. Finley designed the hydraulic side-launching jacking system that assisted with separation of the truss members from the existing connections, moved the North truss and facilitated fit-up of the new bracing members, and provided a means to adjust the camber of the North truss.
The bridge is scheduled to be completed in late spring 2013. For more information about the project and additional photos of the bridge widening, visit Finley’s website at www.finleyengineeringgroup.com (direct link: http://bit.ly/Qmcr0R).