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Underground giants: our six most impressive tunnel systems

They are an essential part of our infrastructure but do not always catch the eye: tunnel systems. In order to build supply routes, street-, metro- and train connections, huge boring machines make their way, piercing under waters, cities and even through mountains. We took a closer look at six of the most impressive tunnel giants.


All the way from the famous Gotthard tunnel to the subway around the corner: tunneling is a story of success of modern engineering art. It has huge requirements for the cutterheads and machines, even today. With the propelling force of up to 316,000 kN, tunnel boring machines (TBMs) quarry various rocks in only one work step. This equals the strength of 800 trucks. Serving as main shield bearings and cross roller bearings, slewing bearings of thyssenkrupp rothe erde® make sure that worldwide everything runs smoothly.

Our thyssenkrupp rothe erde® slewing bearings were involved in the following impressive tunnel projects: 

1. Gotthard Base Tunnel, Switzerland

The length of 57km makes the Gotthard Base Tunnel is the longest railroad tunnel in the world. After 17 years of building it, it was put into service on 1st June 2016 and connects the Swiss cities Bodio and Erstfeld ever since. Both cargo and passenger trains are now able to pass through the Alps. Four TBMs and 2,600 people were involved in the construction. Overall, 28.2 million tons of rock material were broken out.

2. Tuen Mun Chek Lap Kok Link, China

The Tuen Mun – Chek Lap Kok Link project connects the airport in Hongkong and the district Tuen Mun. The two-tube road tunnel runs under the sea. By being roughly10.5km long, it is the longest tunnel in Hongkong and also the deepest one.

3. Water-Tunnel, New Zealand

Manapōuri Hydro Station is the world’s largest hydroelectric plant on South Island. For the plant, two ten-kilometer-long tunnels with a bore diameter of ten meters were dug underneath Lake Manapōuri. 

4. New Elbe Tunnel, Germany

Initially, Hamburg’s New Elbe Tunnel consisted of three tubes. Due to the high traffic volume of more than 100,000 vehicles that cross the river Elbe daily, a fourth tube was built between 1997 und 2002. Here, the used tunnel shield was equipped with a thyssenkrupp rothe erde® cutter head. With an overall diameter of 14.2 meters, it was the world’s biggest TBM at that time.

The tunnel boring machines that came into action building the New Elbe Tunnel in Germany (1) and the Water-Tunnel in New Zealand (2).

5. Shantou Su’Ai Sub-Sea Tunnel, China

The three-lane tubes of the tunnel in Shantou are a little more than three kilometers long and connect the north and the south of the Chinese seaport. The metropolis is divided by an inlet. Therefore, many districts did not have the best transport connections. For the construction of the tunnel, two TBMs with a diameter of almost 15 meters were used from 2018 until 2020. 

6. Subway tunnel in Moscow, Lisbon & Tokyo

Due to the rather soft ground, the so-called EPB-machines (Earth Pressure Balance Shield) were called into action for the extension of the Southwest-Ring-Project in Moscow. As they bored during winter, too, it needed to be taken into consideration that the machine would have to withstand -30°C. During construction, a stretch of 35m per day was reached, which was a record. Metro tunnels were built by TBMs in Lisbon and Tokyo, too. The 2.2km long metro tunnel in Lisbon, Portugal, was built equipped with a three-row roller bearing from thyssenkrupp rothe erde® and a bore diameter of almost 10 meters.


By the way: with an average rate of advance of 23m per day, the 2,000 TBMs, that are equipped with thyssenkrupp rothe erde® slewing bearings as main bearings, have borne and secured 19,200km of tunnel. For comparison: the diameter of the earth is 12,075km. Therefore, the fictive tunnel reaches through the earth almost 1.5 times.