Prof Jerry Connor from MIT, USA presented a seminar entitled ‘Learning from Failure’.

Prof Connor discussed the recent failure of the ceiling panels of the I90 connector tunnel, part of the recently constructed ‘BIG DIG’ highway/tunnel complex in Boston, USA. The panels were supported by links attached to the tunnel roof. The links were anchored by bolts embedded in the concrete roof and secured with expansive epoxy grout.

A failure of the anchorage occurred and the panels suddenly dropped to the roadway. Unfortunately, the panels landed on a passenger car, and one person was killed. The cause of the failure was inadequate anchorage combined with a lack of redundancy in the number of links.

The panel support system has to be completely replaced with Hilti mechanical fasteners which are to be individually proof loaded. The key lesson here is to make sure there is adequate redundancy in load paths, especially when an unproven technology is being used.