Alaskan Way TBM finishes maintenance stop
21 July 2016US - Seattle Tunnel Partners (STP) resumed mining on July 18 following a month of routine and hyperbaric maintenance on the TBM mining the SR99 tunnel, the Washington Department of Transportation said (WSDOT).
Crews inspected and repaired machine components as needed during the maintenance period, which started on June 23. WSDOT said the maintenance period included more than 40 shifts of work under hyperbaric conditions, changing cutting tools and performing other maintenance in the space behind the cutterhead. In all, STP changed 33 of more than 700 cutting tools.
Tunnelling is one-third complete. The machine is currently approximately 120ft (36.6m) deep and will eventually reach a depth of 200ft (60m) along its alignment. STP expects to stop two more times for maintenance before they reach the future north portal.
