More than 15 km of the tunnels for the Stuttgart–Ulm rail project located in the Stuttgart urban area lie in gypsum keuper containing anhydrite, which swells in contact with water. Owing to the swelling pressures that occur and the displacements caused by swelling, major damage has resulted in the case of many tunnels in the past. As a consequence, the corresponding sections of the tunnels in the Stuttgart urban area are driven absolutely dry.

More than 1500 tunnellers from 52 countries met in Bergen, Norway, from June 9 to 14, 2017. The occasion was the 43^rd Annual Meeting of the ITA (International Tunnelling and Underground Space Association) in conjunction with the 2017 World Tunnel Congress (WTC). The Tunnel Congress organised by the NFF (Norwegian Tunnelling Society) in collaboration with the ITA bore the slogan “Surface Challenges – Underground Solutions”. 52 of the 74 ITA member nations were present in Bergen.

When space is scarce in the big cities, construction targets the “third dimension”. This has been the case for quite some time now. Modern high-risers have been featured in urban centres in conurbations since the mid-1800s; the first skyscrapers appeared almost 100 years ago. However, the Swiss SCAUT initiative established just a few months ago is not directed sky high: “The third dimension after all, also leads in the other direction – down below”, as Felix Amberg, the president of the SCAUT development association maintains.

The U5 project in Berlin is one of the most important ongoing infrastructural schemes in Europe for Implenia. On March 22, 2017 the final concrete wall separating the new U5 tunnel from the Brandenburg Gate Metro Station was penetrated. In this way, the gap between U55 (Central Station–Brandenburg Gate) and the traditional U5 (Alexanderplatz–Hönow) has been closed and the tunnel roughwork has been completed, which commenced with the start-up of the “Bärlinde” tunnel boring machine (TBM) back in 2013.