Light-rail tunnel estimate $41 million short, but money is there
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The Ice Age has come back to haunt Sound Transit, as costs to build a light-rail tunnel through the glacial soils of Beacon Hill turned out $41 million higher than transit engineers predicted.
The news arrived via sealed envelopes from two construction teams, whose bids were opened yesterday. The apparent low bid, from Obayashi Corp. of Japan, was $280 million, well above Sound Transit's $239 million estimate.
Despite the higher cost, plenty of money remains to dig the tunnel and finish the rest of the line from Westlake Center to Tukwila.
That is because the agency saved money on four previous contracts: for the trains, the maintenance base, a relatively simple mile in Sodo, and four miles through Rainier Valley. The Link project is 2 percent under budget so far, with contracts yet to be awarded for an elevated section through Tukwila and the retrofitting of the downtown Seattle bus tunnel for joint use with rail cars. In addition, $128 million in reserve funds are available to cover emergencies during work on the $2.44 billion, 14-mile route.
"To still be 2 percent below what we estimated, and be this far along, is a pretty good place to be," Sound Transit spokesman Geoff Patrick said.
The harder question is whether the bids foreshadow problems in funding a future rail tunnel north of downtown, through First Hill, Capitol Hill and the University District.
Geology is the issue. Seattle's hills were formed 14,000 years ago from sediments deposited by retreating ice sheets. The hills are susceptible to earthquakes, and water seeps through them.
Sound Transit initially underestimated the North End challenge when bids for the tunnel came in $300 million above estimates in 2000. Total cost overruns exceeded the voter-approved transit plan by more than $1 billion, auditors accused the agency of inadequate soil research, and the North End segment was postponed.
Learning from its mistakes, Sound Transit drilled a test shaft and mapped the Beacon Hill soils last year. Its investigation found stable clays 150 feet deep, where the underground boarding area and railway tubes will be shaped like a buried pair of binoculars. But near the surface, where a huge elevator shaft will ferry passengers between the hilltop and the deep tunnel, soils are so porous that workers must inject concrete grout into the earth so it won't sink during construction.
Link Director Ahmad Fazel speculated that the inherent difficulty of tunneling, "especially with the kind of soils we have to deal with here," hurt the bidding. One of three finalists pulled out. "The competition was not as much as we had hoped for," he said.
However, last year's soil testing is likely to prevent cost overruns after work begins in late summer, Patrick said. The contract includes a $17 million contingency to cover rising steel prices or extra grouting, money Sound Transit would keep if neither problem arises.
Obayashi's projects include the new Ted Williams Tunnel in Boston, a sewer tunnel in Atlanta and light rail in Los Angeles.
Sound Transit will study details in the Beacon Hill bids and compare them to its north-line estimates to see if those estimates are still accurate, Fazel said.
Preliminary estimates for north-line construction are $1.8 billion between Westlake Center and Northgate — not counting trains, administration and engineering.
The Beacon Hill bids reinforce opponents' belief that a total of $7 billion will be needed to finish 24 miles of light rail from Northgate to just south of Seattle-Tacoma International Airport, said John Niles of the Coalition for Effective Transportation Alternatives, which favors express buses.
Mike Lindblom: 206-515-5631 or mlindblom@seattletimes.com
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