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SR 99 update: TBM reassembly underway

The three final pieces of the stalled SR 99 tunnelling machine’s front shield have been lowered into the access pit for reassembly.

Work on the Alaskan Way Viaduct replacement project has been delayed since the tunnel boring machine (TBM) stalled in December 2013.

As part of the repair programme, crane crews from Mammoet lowered two 98t side body pieces into the pit before lowering the 278t middle shield.

With all of the TBM’s major components now in the pit, crews are focusing on reassembling the machine and preparing for the testing phase of the repair works.

Crews will spend the coming weeks welding the parts back together, in addition to reconnecting hundreds of wires and hoses that are integral to the tunnelling operation.

Following reassembly, contractor Seattle Tunnel Partners and manufacturer Hitachi Zosen will conduct a series of tests to ensure the TBM is ready to resume mining.

Tunnelling is scheduled to resume in late November.

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