Wednesday, March 8, 2023

2010 US-93 Mike O'Callaghan - Pat Tillman Memorial Bridge near Hoover Dam

(Bridge Hunter; 3D Satellite, 9,641 photos)

The bridge has a walkway on the upstream side providing some good views of Hoover Dam.

HooverDamBypass, May 2009

Street View, Mar 2019

Street View, Mar 2019
Highway Engineering Discoveries posted
Concrete Arch Bridge
William Lee Nelson: This looks like the new Hoover Dam bridge.

1 of several photos in desertusa
"When under construction, the bridge was referred to as the Hoover Dam Bypass Project. It is now named the Mike O'Callaghan-Pat Tillman Memorial Bridge. O’Callaghan was a former governor of Nevada and former executive editor of the Las Vegas Sun. Tillman was a professional football player for the Arizona Cardinals who joined the Army in 2002 and was killed in Afghanistan in 2004. (He was killed by friendly fire at the age of 27. [HighestBridges]) The Hoover Bridge bypass re-routes U.S. 93 traffic 1,700 feet downstream from the dam. It's suspended by a 1,060 foot, twin-rib concrete arch, the largest of its kind in North America, and is 1,900 feet long. The bridge is 890 feet above the Colorado River."

The World posted
Hoover Dam, Nevada

Explore USA posted
The Hoover Dam at Lake Mead and The Mike O'Callaghan–Pat Tillman Memorial Bridge arch bridge crossing the Colorado River from Nevada on the left to Arizona on the right.


HighestBridges, Image by Federal Highway Administration, Central Federal Lands Highway Division (FHWA/CFLHD)
"During construction, the proximity of the foundation excavation blasting to the historical Hoover Dam buildings and the desire to preserve the natural state of the canyon walls led to the installation of nets to catch loosened rocks and boulders. Wind had a large effect on the design with the design based on an hourly mean wind of 98 mph with short gusts of up to 125 mph. Vortex shedding was reduced on the main span and columns by introducing Chamfers which are essentially 45 degree cuts at the corners of the box shaped beams. The angular Chamfers also had the unintentional effect of making the structure look more elegant and less bulky. The potential for the tall columns to move from temperature changes required the unique use of spring-loaded bearings in the abutments that allow the bridge to drift back into a neutral position. The 4 massive ribs were built with 4 form travelers. Temporary stays held the arch segments in place as they rose from the abutments. Since the limits of the concrete curing could not exceed 155 degrees Fahrenheit, liquid nitrogen was injected into the mixing truck drums after batching. This reduced the temperature during the hotter months from 85 degrees to 40 degrees. The project had its biggest construction setback on September 15, 2006 when all four of the 50-ton high line cable towers collapsed from high winds. The mishap delayed erection of the arch by nearly two years before a newly designed highline was built."

Dec 2009 Photo by Nathan Morton via BridgeHunter

HighestBridges, Image by Federal Highway Administration, Central Federal Lands Highway Division (FHWA/CFLHD)
"An early construction view with the original highline towers before they collapsed. "

HighestBridges, Image by Federal Highway Administration, Central Federal Lands Highway Division (FHWA/CFLHD)
Two of the form travelers.

The cableway towers. Note the hoists in the lower-left corner.
The towers rise 330' above the future roadway.

The hoists

And this was one of the uses of the cableway.
Transporting precast pier sections with the Cranes (looking southwest)
Top right: View of the partially constructed Abutment 1.
Upper Center: View of the erected precast segments of Pier 2 right column. Visible to the right of this is the footing of Pier 2 left.
Lower Left: Olsen Beal utilizing the two cableway crane to transport and lower a precast segment section for Pier 3 right. Construction personnel stand on the footing of Pier 3 left viewing the operation.

Obayashi / PSM, JV crews unload concrete into the re-mixer and concrete pump located on the Arizona skewback footing at Pier 14. Concrete is delivered to the pump by the cableway crane system via an 8cy concrete bucket. [A rear unloading ready-mix truck carries 9cy.] From the pump, concrete is conveyed to the placing boom where it is directed into the form.

Inside the form traveler system at Arch Segment NV13-LT, Obayashi / PSM, JV crews placed concrete into the bottom slab formwork. The slick line from the end of the placing boom is directing the flow of concrete through an open pour window in the formwork. Other crew members consolidate the placed concrete while carpenters follow behind and close the windows securely as placement advances.

HooverDamBypass, Oct 2008
As seen from the existing US93 Hairpin in Nevada, the left and right Arch ribs project outwards over the Colorado River. The form traveler systems are secured to segments NV10 and cantilevers out to form segment NV11. Forestay cables span from the Arch ribs to the temporary pylons above. The vertical post tensioning bars extend upwards from the Arch rib where Pier 6 will be erected.
[I wish the high-res photo links worked. I think they lifted a whole concrete boom truck onto the arch. ]

Arizona Department of Transportation posted three photos with the comment:
Construction of the Mike O'Callaghan-Pat Tillman Memorial Bridge, which bypasses the Hoover Dam on US 93, occurred between 2005 and 2010. Because of high daytime heat during the summers, concrete had to be poured from mid-air at night and then cooled with liquid nitrogen. 
When it was finished, the bridge, 900 feet above the Colorado River, became the highest and longest arch concrete bridge in the Western hemisphere.
The bridge is maintained by ADOT and Nevada DOT.


Highway Engineering Discoveries posted

Highway Engineering Discoveries posted on Jun 24, 2023

Highway Engineering Discoveries posted
Hoover dam bypass Bridge Construction, USA

Highway Engineering Discoveries posted
Hoover dam bypass Bridge Construction

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