SEATTLE – An enormous drill broke through the east side of Beacon Hill in the city’s south end Tuesday morning, almost a year and a half after it started digging a nearly mile-long light-rail tunnel.
With a crowd of onlookers intently watching, the Japanese-built tunnel-boring machine, with its 21-foot diameter cutter head, slowly churned into view a little after 8:15 a.m.
Pat Gould, who was driving the 375-ton machine, was the first of several underground crew members to emerge from the freshly dug tunnel – the first of two being built for a 16-mile Sound Transit line that will stretch from downtown to Seattle-Tacoma International Airport.
“It felt great,” Gould told The Associated Press after the cheering and clapping died down. “It’s a good day for Sound Transit and Seattle to get this light rail, the first phase of it, complete.”
Sound Transit, a mass transportation agency that serves Snohomish, King and Pierce counties, runs express buses, a commuter train, park-and-ride lots and a light-rail line in Tacoma. Project leaders say the $2.7 billion light-rail line from Seattle to Sea-Tac, approved by voters in 1996, is on schedule to open in late 2009.
In November, voters will have their say on a plan to add another 50 miles of light rail to the system, expand express bus service and improve commuter rail stations. If approved, the projects would cost an estimated $23 billion – a total that includes operations, inflation and debt service over 20 years.
Nearly a football field in length, the tunnel-boring machine is equipped with a laser guidance system that dug the 4,388-foot-long hole within 5 millimeters of engineers’ plans, Gould said.
Manufactured by Japan’s Mitsubishi Heavy Industries, it made about 50 feet of progress per day on average – 60 feet “once we really got going, and once the crews got comfortable with the operation,” he said.
Next up: Sound Transit crews will finish laying the concrete rings that line the tunnel, then take the machine apart, move it back to the west side of Beacon Hill, reassemble it, test it, then start digging the second, parallel tunnel.
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