Seattle Tunnel

Bertha, one of the world's largest tunnel boring machines, emerged north of downtown Seattle on Tuesday shrouded in clouds of dust and chunks of falling concrete, completing the most difficult phase of a plan to build a highway under the heart of the city.

Bertha, one of the world's largest boring machines, will cut through a thick concrete wall at midday on Tuesday if all goes according to plan, completing the most difficult phase of building a highway under the heart of downtown Seattle.

Bertha, one of the world's largest tunnel boring machines, emerged north of downtown Seattle on Tuesday shrouded in clouds of dust and chunks of falling concrete, completing the most difficult phase of a plan to build a highway under the heart of the city.

Bertha, one of the world's largest boring machines, will cut through a thick concrete wall at midday on Tuesday if all goes according to plan, completing the most difficult phase of building a highway under the heart of downtown Seattle.