What is a great drill

Bertha: Gigantic tunnel drill breaks through to the surface of the earth

Bertha dug her way through the earth under Seattle's city center for four years. Now the oversized drilling machine with which the US city took the first step towards an underground freeway has seen daylight again.

The world's largest machine of its kind had to dig its way through a concrete wall to reach the end of its arduous journey. It happened on Wednesday night, the moment is a milestone in the multi-billion dollar construction project that will one day make an aging unearthly highway superfluous. This had also made access to the coast a little more difficult for the citizens of the city.

The Americans gave the drill a nickname that is reminiscent of earlier war jargon: "Big Bertha" was the name of several German guns during the world wars. In the case of the drill, however, the nickname is based on the first name of the former mayor Bertha Knight Landes.

On the way it looked like it wasn't going to work

The machine has a diameter of 17.5 meters and even has its own Twitter account. Bertha's distance to be covered was three kilometers.

On the way it once looked as if the machine would not be able to withstand the ambitions of the project. Critics have long suspected a terrific waste of money. And for a while it looked like they were right.

Shortly after drilling started in December 2013, the machine gave up - because of a steel pipe that it couldn't get past. Until then, they had only covered 305 meters. Bertha also had to be repaired and the drill head reinforced. To do this, the machine even had to be exposed. What exactly caused the drilling stop is now the subject of a legal dispute between the US state of Washington and the construction company. Bertha shouldn't start again until 2015.

The highway project is expected to cost $ 3.1 billion, writes the AP news agency. Judges will probably decide who pays the additional millions of dollars in costs caused by the delay.

Workers will now upgrade the inside of the tunnel. The opening of Highway 99 is planned for 2019 - and is about three years behind schedule. Bertha's mission is now over. Parts of the machine are to be recycled, another part is shipped back to the designer in Japan.