HNTB-designed Devil’s Slide Tunnels Project earns Engineering Project Achievement Award from Orange County Engineering Council

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Event honors the engineering in Southern California; new tunnels opened to traffic earlier today.

Devil's Slide Tunnels in San Mateo County, Calif.

The Devil's Slide tunnels are the first road tunnels constructed by Caltrans in more than 50 years, and as they opened to traffic earlier today, are now the second longest road tunnels in California.

To be recognized by the OCEC is a tremendous honor for Caltrans, HNTB and all the firms that have provided engineering services on Devil’s Slide.

As part of the National Engineers’ Week Awards Banquet, the Devil’s Slide Tunnels Project in San Mateo County, Calif., has earned an Engineering Project Achievement Award from Orange County Engineering Council. HNTB Corporation is lead designer on the project for the California Department of Transportation.

Winners of this year’s awards were announced at a ceremony hosted in Fullerton, Calif. on Feb. 22, 2013. The OCEC event honored the accomplishments, quality and diversity of engineering and related scientific communities in Southern California.

“To be recognized by the OCEC is a tremendous honor for Caltrans, HNTB and all the firms that have provided engineering services on Devil’s Slide,” said Yung-Nien Wang, HNTB project manager and structural lead in Southern California.

The $430 million project represents the first road tunnels constructed by Caltrans in more than 50 years, and as they officially opened to traffic earlier today, are now the second longest road tunnels in California. The project replaces an infamous coastal stretch of California’s State Route 1, which has been subject to lengthy closures from slipouts and rockslides, high maintenance costs and risk of permanent failure.

HNTB worked closely with Caltrans to fully explore alternative designs and construction methods for the twin tunnels. Constructed beneath San Pedro Mountain using the New Austrian Tunneling Method; each one is 29 feet, 6 inches wide by 22 feet, 4 inches high and 4,265 feet long. They are connected by ten emergency cross passages. The project lies along the active San Andreas Fault, with four inactive faults crossing the tunnels. Ten different rock masses are encountered along the tunnel alignment. Despite challenging technical and environmental constraints, HNTB successfully completed the project to the client’s satisfaction.

HNTB Corporation is an employee-owned infrastructure solutions firm serving public and private owners and construction contractors. With nearly a century of service, HNTB understands the life cycle of infrastructure and addresses clients’ most complex technical, financial and operational challenges. Professionals nationwide deliver a full range of infrastructure-related services, including award-winning planning, design, program delivery and construction management. For more information, visit http://www.hntb.com.

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John O'Connell
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