Contractors have faced a particular challenge in gaining access to the underground construction area. Establishing a construction base near the eastern portal was ruled out for environmental reasons, so the only viable solution was to sink a 60m-deep supply shaft at Liebenfeld south of Deutschlandsberg. This allowed equipment to be lowered into a cavern where the TBMs were assembled in-situ.

The supply shaft is served by a spur from the Graz-Köflach Railway (GKB) Lieboch – Wies-Eibiswald line, which is being used to deliver construction materials to the site and remove spoil from the tunnel.

The project is due to be completed in 2020.