Pummersdorfer Tunnel - Water conditions in the shallow tunnel / Pummersdorfer Tunnel - Wasserverhältnisse im seicht liegenden Tunnel

The Westbahn line between Vienna and Wels in Austria is being upgraded to four tracks to improve its capacity and performance for passenger and goods traffic. The opening of the section "Gap-closing St.Pölten-Loosdorf (GZU)" in 2017 completed the four-track Westbahn line between Vienna and Linz. The Pummersdorfer Tunnel is the last tunnel in this section and is designed as a single-bore two-track tunnel with a length of 3.5 km. The tunnel runs close to the surface with a maximum of 25 m overburden in weathered or unweathered Miocene schlier (marl). The driving of the tunnel encountered two groundwater horizons, pore groundwater in the Quaternary cover gravels above the tunnel crown and water in the joints of the Miocene schlier in or just above tunnel level. Some unexpected heavy water inrushes occurred during tunnelling.
The article first gives an overview of the project and the geological conditions and is then concerned with the effects of the groundwater inflows on the tunnelling works and the groundwater use in the near vicinity.