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Elegant Arches, Soaring Spans: C.B McCullough, Oregon's Master Bridge Builder
by Robert W. Hadlow

Hoover Dam Bypass (New Colorado) Bridge Project

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The Hoover Dam Bypass Project (which includes the New Colorado Bridge) is a complex project made up of four miles of roadway (two lanes in each direction), eight bridges, wildlife crossings, a 2,000 foot-long bridge over the Colorado River and various pedestrian and visitor improvements. Because of the magnitude of this project, it will be constructed in four distinct phases: the Arizona Approach, the Nevada Approach, the Colorado River Bridge, and final roadway surfacing. Construction of the Arizona approach has begun followed by the Nevada Approach in mid-2003 and Colorado River Bridge in late 2003. The entire Hoover Dam Bypass Project is expected to be complete in 2007 at a cost of $234 million.

The Central Federal Lands Highway Division (CFLHD) of the Federal Highway Administration (FHWA) is responsible for delivery of Hoover Dam Bypass project for the states of Arizona and Nevada. CFLHD is the managing partner of a multi-agency project management team consisting of the Arizona and Nevada Departments of Transportation, the FHWA, the Bureau of Reclamation, the National Parks Service and the Western Area Power Administration. Comprehensive design services are being provided by the Hoover Support Team (HST), which consists of HDR Engineering (lead), Sverdrup Civil and T.Y. Lin International.

The type of bridge being built is Composite Concrete Deck Arch Bridge.

The river bridge contract is scheduled for construction beginning in late 2003 with completion in 2007.

The composite solution was developed to address the specific design issues inherent to the Hoover Dam site.  It is recommended on the merits of cost, schedule, aesthetics and technical excellence.  The specific advantages of the concrete composite alternative include the following:

  • The concrete composite alternative blends the best of both concrete and steel, using concrete in compression for the arch, and lighter steel for the upper structure.  Concrete is used where it is most economical, and is efficiently placed using a form traveler system that is a proven construction technology for this type of work.

  • The concrete composite offers advantages for accelerated schedule, since the concrete arch can follow on an early foundation excavation contract without the wait for fabrication of arch steel.

  • The concrete composite alternative is the lowest projected cost for the favored solid rib alternatives, and the blend of concrete and steel design detail options allows the greatest flexibility to design for cost efficiency.
  •  The composite distributes construction risks in terms of costs, quality control and schedule.  Concrete casting is completed in a confined form, and runs in parallel with steel fabrication.  The steel superstructure reduces the risk of delays and eliminates many quality control issues inherent with a cast-in-place concrete superstructure in the open environ over the gorge.  The composite structure utilizes concrete where it is most efficient and steel where it is most efficient.
  • The composite structure allows progress to occur in parallel on site during arch erection and in the shop for superstructure steel fabrication, with relative independence between these operations.

The selection of the composite alternative is influenced by a priority given to schedule, budget and compatibility with the Hoover Dam.  A design choice with the blend of steel and concrete also favors the composite as a single alternative with the greatest opportunity for cost control.  The construction schedule criteria favors the composite structure over the all cast-in-place concrete structure.

Information Provided by http://www.hooverdambypass.org


5-16-03 Update

60% Plan Sheets

60% Specifications

The Colorado River Bridge will facilitate the realignment of US 93 and will span the Colorado River approximately 1,500 feet downstream of Hoover Dam, connecting Clark County, NV and Mohave County, AZ. 

The project will encompass all aspects of the construction of this transportation facility, as well as relative minor approach roadway work.  Major bid items include (approximate): 50,500 yd3 structure excavation (various), 2,500 yd3 structural backfill, 20,000 LF rock anchors, 10,000 ft2 wire mesh fence for boulder containment, 500 each rock bolts, 28,500 yd3 structural concrete (various locations, some options between Precast and CIP), 7,235,500 lb reinforcing steel (various locations, some options between Precast and CIP), 380,500 ft2 painting concrete structures, 24 each bearings,  81,000 lb post tensioning strand R/C caps, 40,000 lb post tensioning bars R/C caps, 798,000 lb structural steel furnish arch struts, 798,000 lb structural steel erect arch struts, 103,000 lb post tensioning bars arch struts, cap option (steel or concrete) -1,353,000 lb structural steel furnish steel caps and 1,353,000 lb structural steel erect steel caps and 77,500 lb post tensioning bars steel caps and 5,116,000 lb structural steel furnish fab boxes and 5,116,000 lb structural steel erect boxes or 952,000 lb structural steel furnish concrete caps and 952,000 lb structural steel erect concrete caps, 2000 ft median barrier; along with associated survey, staking, contractor testing, and traffic control. 


2-25-03 Update

The Arizona  Contract has been awarded! The first phase of the Hoover Dam Bypass, the Arizona Approach, is set to begin early this year. The contract for construction services has been awarded to the joint venture team of R.E. Monks Construction and Vastco Inc., of Fountain Hills, Arizona.

The Arizona Approach is the roadway leading from Arizona U.S. 93 to the new Colorado River bridge crossing (approximately 1500 feet downstream of the Hoover Dam).

The Arizona Approach will include:

  • 1.8 miles of four-lane roadway (two lanes in each direction divided by a concrete median)

  • Sugarloaf Mountain Bridge 900-foot bridge spanning a canyon on the east side of Sugarloaf Mountain

  • Traffic Interchange at the intersection of the Bypass, the Hoover Dam Access Road and Kingman Wash Road

  • Wildlife crossings at bridges

  • Drainage improvements

  • Trail access parking

  • Staining of newly exposed rock cuts


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