Jun 23 2008

Coming Up: The Colorado River Bridge

Colorado River BridgePhoto courtesy of the Federal
Highway Administration

View of the Colorado River
Bridge from below Hoover Dam

I first heard about plans to create a new bridge over the Colorado River when I moved to southern Nevada at the end of 1999. At that time, a number of possible locations were being discussed. About the only thing everyone could agree on was that an alternate truck route had to be found for the section of U.S. Highway 93 that crossed the Black Canyon via Hoover Dam. The highway had been designated as part of the North American Free Trade Agreement (NAFTA) route between Mexico and Canada, increasing the commercial traffic on the road to problematic levels. In addition, U.S. 93 has long been a major route for tourists bound for cities throughout Arizona, Nevada and Utah.

Colorado River BridgePhoto by Mark Sedenquist
This is the Nevada side.
Note the two temporary towers and
the beginning of the arch span.

Even without heavy traffic, the twisty, narrow two-lane road is a navigational challenge for trucks, RVs and even cars. One summer evening in 2000, I was stuck in a jam of more than 500 vehicles caused when a tractor-trailer jackknifed on one of the switchbacks on the Arizona side and fell partway off the highway. To make matters worse, temperatures were brutally hot and the wind bordered on gale force. To prevent overheating and running out of fuel, everyone caught in the jam had to turn off air conditioning and engines while we waited for emergency vehicles to—slowly, very slowly—make their way across the dam and start the cleanup. The process stretched into the night, and dawn was breaking when I finally got home. It was graphic evidence that a dam shouldn’t be pulling double duty as a major highway.

Colorado River BridgePhoto courtesy of the Federal
Highway Administration

An artist’s rendering shows the view
toward Hoover Dam.

Even before sabotage became a concern after 9/11, the potential dangers of a truck accident on top of the dam—and the possibility of environmental catastrophe—loomed large in the imaginations of transportation planners and emergency responders. A route known as the “Sugarloaf Mountain Alignment” was selected by the Federal Highway Administration (FHA) as the best route—at least with respect to engineering—for the new bridge. Unfortunately, this plan required the removal of a large piece of Sugarloaf Mountain, which is ceremonially important to Southern Paiute, Mojave, Hopi, Navajo and other Native American people. In particular, the mountain has played a central role in their regard for puha, the life force associated with creation and volcanic activities. The tradition is an old one, as ancient artifacts found in the area reveal. Even so, the FHA won out, and work on the Sugarloaf Mountain Alignment route began in March 2001.

Colorado River BridgePhoto courtesy of the Federal
Highway Administration

An artist’s rendering shows how the
arch is held in place with temporary
cables.

Whether it’s the result of disturbed puha we’ll never know, but the project suffered a major setback in the fall of 2006. Two enormous highline cranes toppled over in a windstorm. Fortunately, the event occurred while no workers were on the site, and no injuries resulted. Work resumed, and at this writing, the new bridge is expected to open in late 2010.

Colorado River BridgePhoto courtesy of the Federal
Highway Administration

New highway under construction
on the Nevada side

The bridge will span the river about 1,500 feet downstream from Hoover Dam and will be supported by one enormous concrete arch. Just over 2,000 feet long, the bridge will rise nearly 900 feet above the water. The project will require the construction of new highway sections in both Nevada and Arizona as well as infrastructure improvements to the Hoover Dam area. Total costs are expected to be around $240 million.

Construction of the arch has just begun. Built from both ends, it is being formed from sequential castings of a special, high-strength concrete. When 53 24-foot-long sections on each side of the arch are finished, they will meet in the middle. During the construction phase, the arch is being held up by cables supported by temporary towers on each side of the canyon. Once joined (completion of the arch is projected for September 2009) the downward force of the arch will support the bridge, and the temporary towers will be removed. Project updates are available online, and a webcam chronicles the progress.

Colorado River BridgePhoto courtesy of the Federal
Highway Administration

Nighttime construction on the
Nevada side of the span —
the Arizona side can be seen
about 1100 feet away.

If you go to the visitors center at Hoover Dam, you can get a feel for the engineering challenges the builders of the great dam faced. But if you want a real-time appreciation for what it takes to conquer the Black Canyon, take a drive down U.S. 93 in the next few months. Enjoy a marvel in the making before it’s a fait accompli.


blogarama.com

2 Responses to “Coming Up: The Colorado River Bridge”

  1. mike booth on June 28th, 2008

    hi that is very interesting seeing how they are coming on the bridge.
    i hope all is well with you guys ,keep up the good work ,talk to you soon .. MIKE…

  2. Mark Sedenquist on June 28th, 2008

    Mike,

    Nice to see you on here — Yeah, this bridge will be a great thing for professional drivers, like yourself, when it is finished.

    Mark

Leave a Reply