A dramatic new concrete arch is joining the setting of the historic Hoover Dam, spanning the Black Canyon between the States of Arizona and Nevada. When complete, the 323 meter arch will be the 4th longest concrete arch in the world, and the longest in the United States. What makes the design distinctive is the combined use of steel and concrete to optimize construction and structural performance. The design is the first arch structure built on such a scale to combine a composite steel deck with a segmental concrete arch and spandrels. In addition, the design is unique in its use of steel sections for Vierendeel struts between twin concrete arch ribs – a feature that both speeds construction and adds ductility to the lateral framing system for extreme seismic loads.
This new transportation facility is designed to greatly enhance mobility in the vicinity of the historic Hoover Dam. The Hoover Dam Bypass will relocate through traffic off the dam and onto a new high-speed, four-lane roadway. The selected Sugarloaf alignment alternative of this facility carries the roadway approximately ¼-mile downstream of the dam, requiring nearly 3.5 miles of new roadway and a 2,000-foot-long bridge with a minimum clear span of 1,090 feet across the Black Canyon, an 800-foot-deep gorge carved by the Colorado River.
The effort is being led by a Project Management Team that includes the lead agency, the Central Federal Lands Highway Division of the Federal Highway Administration, supported by the Arizona Department of Transportation, Nevada Department of Transportation, U.S. Bureau of Reclamation, National Park Service, and the Western Area Power Administration.
The overall project design team is headed by HDR and includes major partners T.Y. Lin International (Colorado River crossing) and Sverdrup Civil (approach roadways).