The Semmering Base Tunnel is designed to reduce gradients and increase the line speed on the Vienna – Bruck an der Mur main line so that when it opens in 2026 the Vienna - Graz journey time will be cut by 35min to 2 hours.

The project entails the construction of 62km of running tunnels, plus 8km of access tunnels, as well as connecting tunnels and shafts.

The tunnel is being dug from multiple sites and workers have already penetrated more than 0.5km into the mountain at Gloggnitz, while work has started at Göstritz on the construction of a 1km-long tunnel to access a large construction site from where work will begin in 2019 on the railway tunnels. Work will start in 2017 on the running tunnels from two other locations - Fröschnitzgraben and Grautschenhof - using a mixture of techniques including boring and blasting. Construction of a new station tunnel portal at Mürzzuschlag will commence in 2019.

Semmering tunnel diagram

Cross-section of the Semmering Base Tunnel.