The new bridge over the Colorado River at Hoover Dam…

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From: Ralph & BA 
Date: 23 August 2012 06:04
Subject:Fwd: The new bridge over the Colorado River at Hoover Dam…

New bridge over the Colorado River at Hoover Dam…
Take notice of the water level of lake Meade at the beginning and then at the end. They were encountering a draught at the time of construction but recovered toward the end.
You will need PowerPoint to see this..


This is totally amazing….
Meet America’s Newest Wonder
You’re about to see a remarkable time-lapse presentation chronicling the 5-1/2-year construction of the new bridge that now towers over the Colorado River and Hoover Dam.
An instant tourist attraction, it stands 89 stories above the Colorado River, commanding unparalleled views of Hoover Dam and Lake Mead. It is the highest and longest concrete bridge in the Western Hemisphere and boasts the world’s tallest concrete columns of any kind.
Dedicated in October 2010, it provides a quicker and safer drive between Phoenix and Las Vegas, eliminating the 75-mile detour and long checkpoint jam-ups that ensued when traffic was banned across Hoover Dam for security reasons.
Its official name is the Mike O’Callaghan-Pat Tillman Memorial Bridge.
It is named after two-term Nevada Governor and decorated Korean war veteran Mike O’Callaghan and Pat Tillman, the Arizona Cardinals linebacker who joined the U.S. Army after 9/11 and was killed in Afghanistan.
What you will see is how the massive concrete arch begins to form simultaneously from both sides of the river…and the amazing joining of both halves of the arch coming together perfectly almost 90 stories above the blue waters of the Colorado.
Keep in mind that all this was being done in extreme climatic conditions where summer heat can exceed 120-plus degrees!
For that reason, much of the concrete work had to be done at night.
Furthermore, liquid nitrogen had to be injected into each load of concrete to keep the pouring temperature at 80 degrees or less to keep the concrete from drying too fast and cracking.
Imagine the planning, the precision, the engineering nightmares.
Have a look for yourself.