The old style ceiling bolt in a Big Dig tunnel is seen on the left and the replacement style on the right, as workers make repairs and upgrades to a tunnel in the project, Tuesday, July 18, 2006, in Boston. Two tunnels were closed for inspections and repairs after 12 tons of ceiling panels fell, killing 38-year-old Milena Del Valle as she and her husband drove through the tunnel July 10 on their way to the airport.
(Photo: CBS)
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