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/306885
26 | ASPIRE , Summer 2008 An emergency project to relocate a portion of the Pacific Coast Highway (U.S. Route 101) away from a large landslide in northern California required two large bridges to span the South Fork Eel River. Although the bridges are within a quarter mile of each other, they are dramatically different structures. The difference in the bridge types resulted from the vastly different terrains at the two crossings of the South Fork Eel River that snaked along in the shape of a giant "U" with a bridge over each leg. The southern leg of the river, with its wide banks, required a 1355-ft-long, three-span, segmental concrete bridge that was 275 ft above the river. The northern leg of the river, which passed through a narrow rock walled canyon, required a 581-ft-long, three-span, cast- on-falsework concrete arch bridge that sits 150 ft above the river. profile SouTH Fork eel river BridgeS (ConFuSion Hill BridgeS) / lEGGEtt, CAlIf. EnginEE r: California department of transportation, Sacramento, Calif. PrimE ContraCtor: mCm Construction Inc., north highlands, Calif. ContraC tor'S SEgmEntal EnginEEr: finley Engineering Group Inc., tallahassee, fla. ConCrEtE SuPPliEr: mercer-fraser Company, Eureka, Calif. form traVE lEr SuPPliEr: AVAR Construction Systems Inc., Campbell, Calif. PoSt-tEnSioning SuPPliEr: Schwager davis Inc., San Jose, Calif. rE inforCing StEEl SuPPliEr: fontana Steel, Stockton, Calif. by Kevin Harper, California Department of Transportation AvOIDINg the relocation of u.S. route 101 required two high- level bridges over the Eel r iver Route 101 is the primary route that provides direct access to California's north coast for commercial trucking and recreational traffic. North of the San Francisco Bay area, this highway is considered the "lifeline of the California's north coast." There has been a recurring problem of landslides around Confusion Hill over the last decade, resulting in frequent road closures and high maintenance costs. When a major landslide occurs that closes both lanes, the traffic south of Confusion Hill may have to backtrack and detour an additional distance of 250 miles. During the past 10 years, over $33 million has been spent on slide repairs. T h e p r o j e c t i n v o l v e s r e l o c a t i n g approximately 1.5 miles of U.S. Route 101 away from the active landslide. The large ancient rockslide complex extends L A N D S L I D E S The emergency project relocates a portion of U.S. Route 101 away from a large landslide requiring two large bridges over the South Fork Eel River. The large landslide extends over 1000 ft above the river enveloping the current highway. The slide is approximately 3000 ft wide. Photos: © Caltrans. The emergency project Aspire_sum08.indb 26 6/24/08 1:40:34 PM