Seattle tunnel, among world's biggest, takes step toward completion (updated)

Kanadevia

04/04/2017 20:19

(Rewrites, adds Bertha emerging, state governor comment) 
    By Tom James 
    SEATTLE, April 4 (Reuters) - Bertha, one of the world's 
largest tunnel boring machines, emerged north of downtown 
Seattle on Tuesday shrouded in clouds of dust and chunks of 
falling concrete, completing the most difficult phase of a plan 
to build a highway under the heart of the city. 
    The breakthrough of the cylindrical drilling machine marks a 
major step in one of the most ambitious American municipal 
projects in recent years. Once complete, 2 miles (3 km) of 
Highway 99, an elevated roadway along a densely populated 
waterfront, will be rerouted to run beneath the city of 650,000 
people.  
    A sinkhole, a two-year delay and a $480 million claim by 
contractors have challenged the $3.1 billion project since it 
began in June 2013.  
    The underground highway, which had initially been slated to 
cost $2 billion and be completed by the end of 2015, has been 
widely compared with Boston's 16-year "Big Dig" tunneling 
project, which suffered through cost overruns, design flaws, 
worker fatalities and other problems.  
    "This is a historic moment in our state's transportation 
history," Washington state Governor Jay Inslee said in a 
statement after the drill's breakthrough. "There is still more 
work ahead but this moment is one worth celebrating." 
    After emerging into a large open-air pit a few blocks from 
Seattle's Queen Anne neighborhood, Bertha will be cut into 
pieces and hauled away over several months.  
    The 57-foot (17 m) wide borer made by Japan's Hitachi Zosen 
Corp  7004.T  cost $80 million and was the largest in the world 
when tunneling started in 2013. 
    As engineers make plans to break down the 6,700-ton 
(6,100-metric ton) machine, work to fill the tunnel with a 
double-decker roadway has already begun. State planners hope to 
have the first car travel through the tunnel in early 2019. 
    While the project's $3.1 billion price tag is comparatively 
small - the Big Dig cost an estimated $22 billion - progress was 
complicated by plans to dig beneath some of the most tightly 
packed neighborhoods in downtown Seattle.   
    Bertha overheated and stalled partway through the project in 
December 2013, putting completion into doubt. Tunneling was 
delayed two years as engineers dug a 120-foot (37 m) access pit 
to make repairs.  
 
 (Editing by Lisa Von Ahn and Bill Rigby) 
 ((steve.gorman@thomsonreuters.com; 213-955-6761; Reuters 
Messaging: steve.gorman.thomsonreuters.com@reuters.net)) 
 
Keywords: SEATTLE TUNNEL/