“The eyes of the world’s tunneling community are on Seattle,” said Martin Herrenknecht, president of a worldwide company building tunneling machines, speaking at the North America Tunneling Conference in Portland this week.
Herrenknecht spoke in glowing terms of the opportunity for the Alaskan Way Viaduct deep bore tunnel to advance the U.S. into the major leagues with Europe and Asia in tunnel technology. Tunnel boring machines, he and other presenters said, are steadily increasing in diameter with better ground control and now safely excavate in all types of soil, rock or groundwater conditions.
At 55 feet in diameter, the Puget Sound’s deep-bore tunnel is in the higher range of tunnels around the world that have been completed largely on time and within budget. Tunneling success has spread to North America, too. While the often-maligned Boston Central Artery project (Big Dig) is cited for cost overruns, another Boston project, the Wastewater Treatment Tunnel, was completed successfully with little notice. Other on-time and on-budget tunnel projects include the 1.2 mile, $538.8 million Allegheny subway tunnel in Pittsburgh and the “Gold Line” rail tunnel in Los Angeles. For navigating complicated soils with far more history and debris than Seattle’s, the just completed tunneling for New York’s No. 7 Subway Line to 34th Street bodes well. According to the city transit authority, “the 24-hour construction operation was completed in six months instead of 2-3 years as originally planned.”
“We do the extraordinary every day and make it seem mundane,” said Brenda Bohlke, president of Virginia-based Myers Bohlke Enterprise and a tunnel association leader, citing successful tunnel projects completed with little news coverage. The industry can deal with changing engineering challenges in cost effective ways, she said. “Long-term economic and environmental benefits that have come from transforming waterfronts and city centers to magnificent people places drive the engineering community, too,” she said.
Conferees indicated that three extremely talented worldwide teams are bidding on the viaduct project and praised the geotechnical and consultative work done by the state Department of Transportation in preparation for the design-build project.
The upbeat mood and praise for the state’s efforts are good news to Gov. Chris Gregoire, who spent a whirlwind week and a lot of political capital in Seattle and Vancouver, British Columbia, bucking up support for the tunnel. At the Port of Seattle, she exhorted a big crowd of union, business and community leaders to urge the Seattle City Council to stay the course on moving forward with a tunnel agreement with the state. She then boarded the Amtrak Cascades with state Sen. Mary Margaret Haugen (D-Camano Island) and state Rep. Judy Clibborn (D-Bellevue) to visit Vancouver’s Canada Line rail tunnel, which was completed months ahead of schedule for the 2010 Olympics.
Our history of building big things underground is one of success. The 1906 railroad tunnel for freight, Amtrak and Sounder passengers built under Third Avenue is still going strong, while the viaduct, built in 1952, has reached the end of its safety life. The Interstate 90 Mount Baker tunnels (wider at 61 feet than the deep bore viaduct tunnel) came in 54 percent below budget in the 1980s during a similarly favorable low bid construction climate. In spite of faulty claims from the tunnel opponents, the Sound Transit’s Beacon Hill tunnel did come in close to budget — overruns occurred in the stations and elevators.
There is no question there will be risks. The 37-mile Brightwater tunnel, while a much different type of project than the viaduct replacement, had two of its four boring machines get stuck and the state is learning lessons. With healthy contingency funds, independent experts hired separately by the state and Seattle City Council, and yearly advances in technology since experts were first brought here in 2008 to encourage a deep-bore tunnel, however, the return on investment for the tunnel looks brighter than ever. And the whole world is watching.
BRUCE AGNEW is policy director of the Cascadia Center, a research organization focused on transportation at the Discovery Institute in Seattle.