This talk will be a short history of the construction to date of the Lyon Turin high speed rail project, and specifically the 57 km long transborder underground section between St Jean de Maurienne in France and Suza in Italy, with a focus on the SMP4 contract.
The particularity of this contract is that it was a geotechnical reconnaissance tunnel, on the axis of the running tunnel, and at the finished diameter.
Before this 11 km section of tunnel was constructed, partly by tunnel boring machine, and partly by traditional drill and blast, it just was not known if the construction was actually possible, given the highly tectonised carboniferous ground in this area that could not be avoided, combined with 700 to 900 m ground cover.