When it comes to the tunnel-boring machine Bertha (to quote the Velvet Underground), “the first thing you learn is you always gotta wait.” But after a long morning of careful preparations and safety briefings, crews on the Seattle waterfront finally lifted the first piece of the long buried Bertha to the surface.
Today’s piece weighs 270 tons and was the first of three parts that make up the shield, just behind Bertha’s face. The shield protects the inner workings of the machine and must be removed before the main cutterhead can be lifted for repairs.
The lift occurred this afternoon, later in the day than expected, a result of crews taking a slow and careful approach. According to the Washington State Department of Transportation, the process was designed to take as long as it needed to get it right, which seems to be the new refrain from WSDOT and its contractor, Seattle Tunnel Partners.
The part removed from Bertha today was the upper front portion of the shield. Initially, STP said workers would use the "super crane" shipped in for the 2,000 ton cutterhead's removal, but opted instead for a more normal, albeit tall crane.
The lift was, as expected, slow, the giant crane swiveling before carefully placing the swaying piece about 50 feet away from the access pit. Crews in bright jackets steadied the u-shaped piece with thin, yellow ropes, a funny sight amid such massive machinery.
WSDOT representatives had no word on when the next piece of the shield will be lifted. A few weeks ago, STP’s Chris Dixon said he hoped to have all the pieces on the surface by the end of March, but cautioned that things would likely change.
The real show stopper will be when the cutterhead is lifted. A six-legged, 105-feet-tall Mammoet super crane could be seen behind the access pit, crew members clearly preparing it for the future lift.
The crane will straddle the access pit in order to hoist the 4 million pound cutterhead and turn it horizontally. After it is brought up, crews will repair the broken seals and replace the main bearing, before everything is lowered back into the pit and re-assembled.
WSDOT and STP say, very tentatively, that they hope to have Bertha ready for tunneling by the end of August.
