Arlington, Va. – At nearly 900 feet above the Colorado River and 1,900 feet long, the Hoover Dam Bypass helps to protect the security of the Dam by removing through traffic from US 93, reducing the vulnerability to a terrorist attack and also protect the most sustainable source of electricity and a scarce water supply for the entire Southwest.

In recognition of the challenges to build such a structure in a difficult environment, the Hoover Dam Bypass Bridge was honored with the American Society of Civil Engineer’s (ASCE) 2012 Outstanding Civil Engineering Achievement (OCEA) award. The announcement was made at the Renaissance Capital View Hotel in Arlington, Va. during the Society’s annual OPAL Gala.

The structure, officially known as the Michael O’Callaghan/Pat Tillman Memorial Bridge, was constructed in a harsh environment where temperatures reached triple digits during the day. The structure is the highest and longest arch concrete bridge in the Western hemisphere and features the world’s tallest concrete columns.

Because of the 800-foot gorge below with rock cliffs, steep canyon walls and winds of up to 70 miles per hour, the contractor used two 2,500 foot long cableways connected to 330 foot high towers on each side of the canyon to transport the construction crews and 50 tons of equipment and material into place during the construction. Due to the high heat, concrete was poured from mid-air at night and was cooled with liquid nitrogen filled tubes.

The bridge is part of the five-mile long bypass that consists of four lanes of roadway, eight bridges, interchanges in both Arizona and Nevada and over 3.6 million cubic yards of shot rock excavation.

The project was built for $240 million without a dispute or claim by contractors. Obayashi Corporation and PSM Construction USA were contractors for the bridge while HDR, T.Y. Lin International and Jacobs Engineering were the design and support team. The project is owned by the Arizona Department of Transportation, the Nevada Department of Transportation, the U.S. Bureau of Reclamation, the Western Area Power/Administration and the National Park Service. The Central Federal Lands Highway Division of the Federal Highway Administration was the project and program manager.

The other finalists were:
Cherry Island Landfill Vertical Expansion Project, Wilmington, Del.
Nacimiento Water Project in San Luis Obispo County, Calif.
US 191 Colorado River Bridge in Moab, Utah
Willamette River Combined Sewer Overflow Tunnel, Portland, Ore.

Past winners of the OCEA Award have been:
Louisville Water Company’s Riverbank Filtration System
China’s Sutong Bridge, Nantong City, Jiagsu Province, China
Groundwater Replenishment System, Orange County, Calif.
Woodrow Wilson Bridge outside Washington, D.C.

Entries for the 2013 OCEA award are due June 1, 2012. More information about the award is available atwww.asce.org/OPAL.