THE CONCRETE BRIDGE MAGAZINE

FALL 2017

ASPIRE is a quarterly magazine published by PCI in cooperation with the associations of the National Concrete Bridge Council. The editorial content focuses on the latest technology and key issues in the Concrete Bridge Industry.

Issue link: http://www.aspiremagazinebyengineers.com/i/879956

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PROJECT SH-55 Over North Fork Payette River Bridge by Leonard Ruminski, Idaho Transportation Department The project is located in the small resort town of Cascade, Idaho, on a two-lane scenic highway that is also a vital north-south link within the state for both commercial and tourist traffic. Any prolonged traffic interruptions on this highway would have significant impacts as there is no practical detour available. The existing 65-year-old, three-span steel girder bridge crossing a 20-ft-deep, 190-ft-wide river was classified as structurally and functionally deficient, and was originally scheduled to be replaced in 2017. However, due to excessive corrosion of exposed pier piles, the bridge could no longer support heavy truck loads, causing traffic restrictions along the route and impeding commercial traffic. The Idaho Transportation Department (ITD) temporarily addressed the issue by encapsulating 50% of the corroded piles with epoxy-filled jackets, which allowed lessening of traffic restrictions. But to achieve full mobility as soon as possible, the bridge replacement completion had to be accelerated by two years and was set for October 2015. To minimize impacts on the traveling public and local businesses, the new structure was to be erected by accelerated bridge construction methods with precast concrete elements that would allow rapid assembly in the field. The bridge removal and replacement were to be performed in two stages while maintaining two-way traffic through the construction site at all times. This required a 10-ft shift in the permanent roadway alignment and construction of long, mechanically stabilized earth (MSE) retaining walls at each end of the new bridge, due to right-of-way limitations. MSE walls with precast concrete panel facing were also used instead of conventional wingwalls at each abutment. The bridge layout is oriented on a north-south alignment. Access within the river was only available on the east side of the bridge, where a modular temporary work platform was erected along the existing bridge during stage 1 construction. This working bridge was used to remove the eastern part of the existing bridge and to construct stage 1 of the new bridge. On the west side of the bridge, the existing topography at abutment 1 and the wetland area at abutment 2 made access and construction of a working platform impossible. Low-hanging electrical power lines also ran parallel along the east side of the bridge, making crane operations difficult. Therefore, during stage 2 construction, the remaining part of the existing bridge was used to support equipment for installing piles and the precast concrete pier wall and to allow erection of the girders. Piles for the new bridge were installed through openings cut in the existing deck, so the new pile spacing was designed to fit between the existing bridge girders. Using the existing bridge as a work platform (cont. next page) PROFILE SH-55 OVER NORTH FORK PAYETTE RIVER BRIDGE / CASCADE, IDAHO BRIDGE DESIGN ENGINEER: Idaho Transportation Department, Boise, Idaho PRIME CONTRACTOR: RSCI, Boise, Idaho PRECASTER: Hanson Structural Precast (now Forterra Structural Precast), Caldwell, Idaho's PCI-certified producer PILE FOUNDATION INSTALLATION AND PRECAST CONCRETE ERECTOR: Inland Crane, Boise, Idaho

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