SEATTLE — The last piece of the world’s largest tunnel-boring machine has been lifted from its disassembly pit beneath Seattle.

State Department of Transportation officials announced the latest milestone Wednesday in the multibillion-dollar venture to replace an aging highway along the city’s waterfront.

The machine known as Bertha finished tunneling its 1.75-mile (3-kilometer) journey in April.

Workers continue to prepare the tunnel to handle double-decker lanes of a $3.1 billion underground highway project that will replace the Alaskan Way Viaduct, which was damaged in a 2001 earthquake.

The tunnel is set to open in 2019, three years behind schedule.

Bertha had only drilled about 1,000 feet (305 meters) when it hit a steel pipe and stopped in December 2013. Crews then pulled it out for repair.

Exactly what caused Bertha to stop will be the subject of litigation between the state and the contractor.