Best Bridge (Span Greater than 150 Feet) - Angeles Crest Bridge #1, Wrightwood, Calif.
Best Bridge (Span Greater than 150 Feet) - Angeles Crest Bridge #1, Wrightwood, Calif.
This bridge is located in a remote mountain area where a landslide had eliminated the roadway linking a resort town with a major metropolitan area in March 2005. The California Department of Transportation wrestled with various solutions that were complicated by the active nature of the slide. Efforts to stabilize the mass of rock proved ineffective and therefore the only logical solution was to place the abutments on stable soil comfortably outside the slide limits. This decision meant that the bridge span would reach to over 200 ft. A cast-in-place structure was quickly eliminated because falsework could not be placed on the sliding mass of rock and soil. Steel was dropped as an alternative because of its cost and the six-month delivery schedule. After careful consideration, precast concrete was chosen as the best solution, with the ultimate decision resulting in 8 ft 0 in. deep, 208-ft-long spliced precast bulb-tee girders. Because of the narrow mountain roads, the 208-ft-long girders were divided into three pieces—two 56 ft end sections and one 92 ft center section—so that they could be maneuvered up the two-lane road that led to the site. Special considerations were necessary because of the potential for lateral instability while transporting the girders up the winding roadways. In addition to these intense logistical considerations on the site, the concrete girders had to reach 8500 psi at 28 days while simultaneously maintaining at least 6% air content. This …
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