Tunnel boring machines are some of the most powerful tools in modern construction, capable of creating tunnels through some of the toughest materials on Earth. These machines have revolutionized the way we build underground infrastructure, from transportation systems to water and sewage pipelines.

Here are the ten most impressive tunnel boring machines in the world:

Bertha – Seattle, USABertha is the largest tunnel boring machine in the world, measuring 57 feet in diameter and weighing 7,000 tons. It was used to dig a 1.7-mile-long tunnel under downtown Seattle for the Alaskan Way Viaduct replacement project.

TBM Alice – Melbourne, AustraliaTBM Alice is a 300-ton machine that was used to dig the tunnels for the Melbourne Metro Rail Project. It measures 7 meters in diameter and 120 meters in length.

Gottardo – SwitzerlandGottardo is the world’s largest tunnel boring machine used in the construction of the Gotthard Base Tunnel in Switzerland. It measures 410 meters in length and weighs 4,000 tons.

Big Becky – CanadaBig Becky is the largest tunnel boring machine in Canada, measuring 14.4 meters in diameter and 140 meters in length. It was used to dig the Niagara Tunnel Project, which is the largest hydropower project in the country.

Harriet – Washington D.C., USAHarriet is a 26-foot diameter tunnel boring machine that was used to dig the Anacostia River Tunnel in Washington D.C. It weighs 1,200 tons and is 420 feet long.

Seli – ItalySeli is a 70-meter long tunnel boring machine that was used in the construction of the Marmaray Tunnel in Istanbul, Turkey. It was one of the first machines to use a slurry shield to dig through soft soil.

Lærdal – NorwayLærdal is the world’s longest road tunnel, stretching 15.23 miles under a mountain in Norway. The tunnel was dug using a fleet of tunnel boring machines, including Lærdal, which measures 12.2 meters in diameter.

Kaisyuan – TaiwanKaisyuan is a 30-meter diameter tunnel boring machine that was used to dig the Kaohsiung MRT Red Line in Taiwan. It is one of the largest tunnel boring machines in the world.

Florence – ItalyFlorence is a 9.9-meter diameter tunnel boring machine that was used to dig the Florence Metro Line 3 in Italy. It is the largest machine used in the project and weighs 2,000 tons.

S-300 – RussiaS-300 is a 19-meter diameter tunnel boring machine that was used to dig the Moscow Metro’s Big Circle Line. It is the largest machine used in the project and weighs 2,500 tons.

These ten impressive tunnel boring machines are just a few examples of the power of modern engineering and construction technology. As the need for underground infrastructure continues to grow, we can expect to see even more impressive machines being developed to dig deeper and faster than ever before.

Video: