Construction materials for the 11.7km western section of the €5.4bn tunnel are being delivered by rail using a purpose-built branch line from St Paul.

The 2.4km eastern section at the Deutschlandsberg portal has already been completed, while work began on the 18.8km central section in 2011. It is anticipated that the TBMs constructing the central and western sections will meet in 2016 in the southern bore and 2018 in the northern bore.

The high-speed line is due to be completed in 2023.