The TBM named “Kätchchen” used to drive the Boßler Tunnel began its work in mid-April, 2015. The machine built by Herrenknecht first tackled the eastern bore, which will one day accommodate the track running from Ulm to Stuttgart. It advanced from the start-up section at the Aichelberg portal up the Alb towards the access tunnel already produced at Umpfental near Gruibingen.
Mathias Breidenstein, the project manager of the DB Projekt Stuttgart–Ulm GmbH for the Alb ascent section on the new Wendlingen-Ulm rail route commented: “the engineers at the Boßler Tunnel have worked a long time for this day. We are delighted that the cutting wheel with 11.39 m diameter propelled by almost 6200 HP is now continuously eating away at the rock thus advancing the approx. 2480 t heavy and 110 m
long TBM. During the first two months the tunnellers get used to the rock and the machine. In this phase we make less progress prior to increasing the rate of advance to try to accomplish some 500 tunnel metres per month”. Essential measurements on the surface accompanied the start of excavation. The pedestrian and cycling path immediately in the vicinity of the TBM start-up zone had to be closed while the measurements were carried out. I
TBM is applied for a longer Distance
During recent months the railways and the contractor have concentrated on optimizing the Boßler Tunnel construction scheme. Intensive investigations of the geological conditions for the 8806 m
long tunnel revealed that the geology permitted the TBM to be applied for a substantially longer distance. Previously it was intended to use mechanized means over a length of some 2.8 km per tunnel tube. “Now we are planning to excavate around 7500 m in the eastern bore, which is being tackled first, then as much as 8500 m in the western one – in other words almost the entire distance – with the TBM”, as Breidenstein explained. “In this way we can produce the Boßler Tunnel with plenty of time to spare and also reckon with substantial savings worth many millions”.