Tysons Metro tunnel breaks through
It was late Wednesday night and a team of roughly 30 engineers, technicians and laborers were toiling away inside a massive, 29-foot-wide tunnel buried beneath Tysons Corner, drilling away sand, gravel and clay.
And then, suddenly, voila. After 13 months, the half-mile tunnel -- at $85 million the costliest and most complex engineering feat of Metro's 23-mile extension from East Falls Church to Dulles International Airport and beyond -- was all hollowed out.
"We worked two shifts, 24 hours a day, to do this, more than 100,000 man hours," said Dominic Cerulli, the engineer for Bechtel, which is in charge of building the tunnel. "We just stopped and celebrated. It's a big achievement for us."
Building the tunnel has been tricky. The tube is technically two tunnels, one each for inbound and outbound trains. It is tucked 40 feet below a traffic-clogged intersection of International Drive and Route 123 near the Tysons II Galleria, where 3,500 cars and trucks pass each hour. One wrong move by a wayward drill or truck and foundations could shift or water or gas lines could get cut.
The 2,400-foot tunnel is designed to carry passengers to two of the four Metro stations in Tysons along the under-construction rail extenstion, commonly called the Silver Line. It solves one of the most challenging problems for planners by bypassing a 515-foot-tall slope in the middle of Tysons, which is too steep for trains to traverse.
The first leg of the Silver Line, which is about 20 percent complete and is set to open sometime in 2013, will extend more than 11 miles from East Falls Church through Tysons to Reston. The tunnel is set to be completed by late 2011 before it is turned over to crews laying the track lines. The second leg will take commuters out to Dulles International Airport and Loudoun County. Projected costs for both phases have ballooned, to nearly $6.6 billion.
Cerulli and members of his team led U.S. Sen. Mark Warner (D-Va.), U.S. Rep. Gerald E. "Gerry" Connolly (D-Va.) and about a dozen reporters through the excavated tunnel Monday afternoon.
"This has been gestating for a long time so it's great to see it finally done," said Connolly, a first-term incumbent facing a tough reelection fight with Oakton businessman Keith Fimian. "If they had built this when Dulles first opened, imagine how much would have been saved."
Work on the tunnel started on Sept. 21, 2009, and Cerulli said the project is a few weeks ahead of schedule.
-- Derek Kravitz
| October 25, 2010; 3:30 PM ET
Categories: Commuter Rail, Metro, Silver Line, Transportation Politics, Tysons Corner, Virginia
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