Grouting work done earlier in the week was a possible cause of a bulge in the lining of a train tunnel under the River Thames. Two trains hit the bulge before the line was closed, but neither train derailed. [Source: New Civil Engineer]
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Seattle Light-Rail Tunnel Likely to Break Ground This Year
Thanks to approximately $100 million from President Bush’s proposed 2009 budget, the $1.8 billion project creating a light-rail line from downtown Seattle to the University of Washington is likely to break ground some time this year. The project will involve twin bored tunnels on the order of 3 miles in length. It is scheduled to open for use in 2016.
There is another notable tunnel project associated with the Seattle Light Rail, known as the Beacon Hill tunnel which I have blogged about before.
Cologne Tunnel Collapse: Investigations Focus on Tiebacks and Groundwater
The latest information to come out of the collapse of a subway tunnel excavation in Cologne, Germany is that investigators are evaluating the ground anchors or tiebacks that were holding open the subway tunnel excavation. There doesn’t appear to be much information available to the public yet, and the New Civil Engineer article mostly quoted academics saying an anchor failure “could” have caused the collapse. Apparently at the time of the collapse, the excavation had reached the bottom depth after the slurry walls had been constructed along with the ground anchor system. Crews were supposedly working on the base slab which would have undoubtedly stiffened up the whole system. For what its worth, an anonymous comment left at the bottom of that article indicated that after half of the debris had been excavated, the diaphragm walls were still intact and without apparent displacement. So what other theories have been floated? Read on for more info. (Image Credit: New Civil Engineer)
US House Passes National Tunnel Inspection Program
The US House of Representatives passed legislation approving a national tunnel inspection program. This of course came about as a result of a fatal accident from 2006 in a tunnel on Boston’s Big Dig project where a concrete ceiling tile fell on a car killing one person. More after the break.