By July of this year it had bored 6.4km of the 11.5km tunnel. Following completion of the remaining distance due by early 2017, contractor Seli Overseas will hand over to main contractor, SK Engineering and Construction.

A spokesman for the manufacturer said of the geology: “The TBM has been boring through different formations, mainly mudstone, sandstone and siltstone with an average UCS of 80MPa and peaks up to 200MPa. The TBM has gone through fractured zones as well and crossed 3 faults successfully on its way. The smooth and close cooperation between Seli Overseas and Terratec in design, technical solutions and execution has been key to achieve this.”