One of the major construction projects of the city of Frankfurt is entering another decisive phase. We are talking about the extension of the U5 line into the Europaviertel. Already a few weeks ago, the giant tunnel boring machine (TBM) EVA has started its driving work for the second tube. This has now been announced by head of transport Klaus Oesterling: "We are pleased that after a speedy conversion of the tunnel boring machine, the second driving has now started on schedule."
The north tube that will be created as a result will run roughly parallel to the south tube that has already been constructed. Over the next few months, EVA will now drive through the already constructed construction pit enclosure of the future Güterplatz station on the 840-metre long section and then continue to bore its way between Hohenstaufenstraße and Mainzer Landstraße to a few metres in front of the sealing structure on the existing building underneath the Platz der Republik. "Mechanical driving of the second tube is expected to last until the summer of 2021," said the commercial managing director of Stadtbahn Europaviertel Projektbaugesellschaft, Florian Habersack.
Under Platz der Republik, the connection of the tunnel tubes to the existing structure will be made by mining using excavation and caulking work. The mining tunnel work is necessary because the TBM cannot drive through the existing wall including still existing old auxiliary constructions from the 1970s. Therefore, for safety reasons, manual and mechanical driving of the remaining section is necessary.
By the end of September 2020, EVA had completed its work for the mechanical driving of the first tube. In the months that followed, the individual machine components, known as the trailing elements, of the tunnel boring machine were dismantled in parts, pulled back through the finished tube into the launch pit and reassembled for driving the second tube.
"The fact that a tunnel boring machine of this type has never been used before in the construction of Frankfurt's subway network makes the driving of the two tubes a fascinating project for everyone involved. At the same time, we are gaining experience for future tunnel construction projects in Frankfurt," says Michael Rüffer, who as VGF Managing Director is responsible for the Technology and Operations divisions, explaining the special nature of the major construction site.
According to current plans, the 2.7-kilometer-long U5 subway line extension is scheduled to go into operation in the course of 2025. So there is still a lot to do before the first trains will run through the tubes.