The Bodio-Faido section of the Gotthard base tunnel has also been the subject of less welcome attention in the press recently after articles appeared in Swiss newspapers giving the impression that the running tunnels were being excavated at too small a diameter.
AlpTransit, the scheme builder, issued a release defending the tunnel construction specifications and methodology, which has called for significant amounts of profiling work to be carried out behind the TBMs boring the tunnels. It said: “in the section Bodio-Faido the tunnel cross section was selected correctly due to the geological situation.” If the tunnel excavated diameter had been increased, it would have needed to be 500mm greater than how it has been driven, which would have cost “substantially more than the reprofiling”.
The controversy seems to mainly surround the jamming of the TBMs for the east and west running tunnels in the spring due to squeezing ground. After the TBMs restarted, a 300m long section distorted by 500mm. This section was re-profiled with excavator mounted breakers and cutters and has caused a five month delay to other works.
AlpTransit defended the work saying it was usual in tunnel construction and was likely with squeezing ground when tunnelling through mountainous regions.
