Obayashi Corp.’s civil division is at work on the Colorado River Bridge, which is being built near Las Vegas and about 1,500 feet down river from the Hoover Dam.

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With the combination of its own talent and its international parentage, the U.S. civil division of Obayashi Corp. has gained “staying power” in its industry, Business Development Manager Patrick Stratton says. Based in Tokyo, Japan, the company is one of the leading general contractors in its home country.

Its U.S. civil division, founded in 1979, operates from its home office in South San Francisco, Calif., and provides civil engineering and construction services in the United States and Canada. Stratton notes that the division now employs a staff of 600 and enjoyed $250 million in sales last year.

In addition to financial stability, Obayashi has operations worldwide, which provides the division “with a pool of engineers and other construction professionals we can draw on, [with] relatively short notice,” he says.

This allows the division to cope with unique projects. It took advantage of this assistance on its Beacon Hill project in Seattle, where it is constructing two new earth pressure balance (EPB) tunnels for the city’s new light rail system.  

EPB is a tunneling approach that uses a specialized tunnel-boring machine to control weak or flowing grounds by using modified soils to maintain pressure against the tunnel face. Obayashi’s Technical Research Institute, funded, staffed and equipped by the company since 1948, played a major role in the development of EPB techniques and equipment for the worldwide tunneling industry. Obayashi’s client on the project is Sound Transit, the transit provider for the Central Puget Sound region.

The project requires the construction of two large-diameter tunnels through Beacon Hill, with a 200-foot-deep station in the center, Stratton says. Unfortunately, “The soils there are like gravel, so they’re not a soil that stands up well,” he says.

To cope, the division is not only utilizing the experience of its own associates, but also engineers from its Tokyo office, Stratton says, noting that shaft and tunnel excavation are nearly complete, with rails now being laid and interior finishes for the two stations installed on the $280 million project.

Building Bridges
The civil division is also at work on two significant bridge projects. These include a seismic retrofit of the northern approach to the Golden Gate Bridge on San Francisco Bay, where Obayashi is in a joint venture on the project with Shimmick Construction Inc., based in Oakland, Calif.

“It’s principally concrete work with some steel work, keeping in mind that the Golden Gate Bridge is not only a certified historical structure, but one of the generally recognized Seven Wonders of the World,” Stratton describes, adding that construction will begin later this summer on the $82 million contract.

In addition, the division is now at work on the Colorado River Bridge, which is being built near Las Vegas and is “about 1,500 feet down river from the Hoover Dam,” Stratton says. “It’s really a beautiful bridge involving a flat deck over a concrete arch, from wall to wall in the canyon.”

The bridge’s deck will be 900 feet above the river, and allow main traffic to bypass the dam, Stratton says. The bridge’s open spandrel arches, when complete, will make up the longest concrete arch span in the U.S., and the fourth in the world. The arches are being cast in place with concrete using a slip-forming technique; the concrete piers were precast and set into place; and the cast-in-place deck sections will lay on steel tub girders. “That’s a highly technical process, [building] this arch from each end, into the center,” he says. The company is partnering on the project with PSM Construction USA Inc., based in Brisbane, Calif.

Defying a Reputation
Underground construction carries a reputation for being dangerous, Stratton says. However, “It’s probably safer than most construction anymore, because of the efforts that companies like ours and others in our industry put into safety,” he says.

To maintain safety, the division has employed a full safety staff on every project, Stratton says. In addition, Obayashi has at least one safety person on every work shift.

“We expend a lot of time, effort [and] money to maintain a safe working environment, both in personnel attitudes and physical jobsite organization,” he asserts.

The division plans to continue specializing in complex underground projects, he says. However, “We’ve expanded our efforts,” Stratton says, noting that the company is also focused on surface work, with “water treatment facilities, complex highway facilities and specialized bridge construction.”

Environmentally Focused
Founded in 1892, Obayashi says it is among the world’s leading general contractors. “Obayashi is equipped to implement every phase of any construction project and can act as [a] consultant, systems designer, engineer or architect,” it says.

According to President and CEO Toru Shiraishi, the company has focused strongly on environmental initiatives. “We have been working on the reduction of carbon dioxide emissions through the enforcement of energy-saving operations and anti-idling efforts, and the reduction and recycling of construction waste through zero-emission programs implemented at all our construction sites,” he explained in a statement.