More and more electricity from renewable sources, hydrogen as an alternative energy source, and the expansion of district heating: the energy transition is in full swing worldwide, particularly in industrialized countries. It requires an enormous amount of new underground infrastructure for the generation and transportation of environmentally friendly energy. This also presents new challenges and opportunities for the tunnelling and trenchless construction industries and for manufacturers of mechanized tunnelling technology. The required infrastructure can be built using both tunnelling and trenchless installation methods. Which method offers the optimal solution depends on many factors, such as the intended use, size and location of the project. Using specific examples, this article presents the advantages in the realization of different types of infrastructure for the energy transition.

In 2021 the Västlänken project (West Link), a railway tunnel underneath the city centre of Gothenburg, has been presented in tunnel-issue 06/2021. Three years later, several sections of the tunnel structure have been handed over for fitting out and track laying, while other parts of the tunnel are in full production process. This article gives an update on the project status and focuses on selected technical solutions, such as concrete columns supporting large rock caverns and one of the first NATM-drives in Sweden.

SBB is renovating the Simplon Tunnel over the next four years. The first construction phase started at the beginning of February 2025.

The Chesapeake Bay Bridge-Tunnel in Virginia, USA, has been one of the largest structures of its kind since it opened in 1964. Until now, the Thimble Shoal Tunnel has been a bottleneck for motor traffic. Over a distance of around two kilometres, traffic has so far been restricted to two lanes. This is set to end in 2028. A major milestone for the expansion has now been reached: TBM tunnelling for the new parallel Thimble Shoal Tunnel was successfully completed at the end of January 2025.