The beauty of barging
On Nov. 23, crews started barging soil from the tunnel dig site to a disposal facility near Port Ludlow. Adding barges to the fleet of trucks hauling away soil has greatly improved the speed and efficiency of the tunneling operation.
The reason for that is simple: Bertha is moving a lot of soil – soil that has to be taken away to make room for more soil. If crews removing it can't keep up with Bertha, the bin where the soil is stored gets full and the machine has to slow down.
It takes up to 40 trucks to haul away the 1,000 tons of soil that Bertha displaces each time she builds one ring of the tunnel. One barge can carry up to four rings worth of soil, or the equivalent of 160 truckloads.
Or, to put it in different terms: Bertha + barges + trucks = smooth tunneling.