SEATTLE -

Seattle's giant drilling machine has passed the halfway mark as it digs beneath the city to complete a new highway tunnel.
   
The Washington Department of Transportation said Monday that the drill known as Bertha has passed the Pike Place Market, moving beyond the halfway point on the nearly 2-mile tunnel of the Highway 99 project.
   
The $2.1 billion tunnel to replace the earthquake-damaged Alaskan Way Viaduct was supposed to open in late 2015, but the boring machine broke down and the project hit other snags.

State transportation officials estimate the four-lane tunnel will be completed by late 2018 and would open to traffic in early 2019 after crews connect the tunnel to existing roadways.
   
The viaduct carries about 100,000 vehicles along Seattle's waterfront each day.