Precast Solutions - November/December 2008 - (Page 17) Precast concrete headwalls and wingwalls complete the structural system and retain backfill. Developed in 1966 in Switzerland, the BEBO Arch System uses the fundamentals of soil-structure interaction to achieve superior strength and stability. BNSF MAINTAINS UNINTERRUPTED Elevation of BEBO precast concrete arch system over Burlington Northern Santa Fe railroad tracks. Drawing courtesy: WSDOT TRAIN SERVICE Two to four trains run each day at the project site. The primary concern for BNSF Railway Co. was maintaining uninterrupted rail service on the Kettle Falls Subdivision for customers from regions north of the tunnel. PRODUCTION AND TRANSPORT In just 20 days in early 2008, BNSF constructed a parallel track at the site, called the BNSF Shoofly. The first reason for a secondary line was that BNSF needs to be able to expand the system to meet the demands of growing freight transportation by rail. The second reason for building the additional track was to allow adequate space for construction of the cast-in-place concrete footings for the BEBO Arch System. Providing this second rail line at the construction site was critical, as BNSF’s soil slope and shoring requirements (to ensure safe operations) restricted excavation activities next to the existing single track. Central Pre-Mix of Spokane Valley, Wash., fabricated the precast concrete components for the BNSF railroad project. Beginning in December 2007, about five pieces per day were cast at Central’s facility. When scheduled for installation, flat-bed trucks were used to transport the precast arch sections to the job site. BEBO arches are transported in the as-cast, or horizontal, position perpendicular to the final erected structure. The units were hoisted by crane at the construction site and rotated to the vertical position before being set in place on footings. NOVEMBER/DECEMBER 2008 | PRECAST SOLUTIONS 17
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