A new high-capacity railway link between Vienna and Sankt Pölten is under construction as part of an overall Austrian railway (ÖBB) infrastructure project. An important component of this line is the Wienerwald Tunnel of 13.4km length, which passes under the Vienna Woods to connect the western outskirts of Vienna with the Danube plain near the city of Tulln in Lower Austria. In an effort to ensure a satisfactory mass balance within the contract section. The Taglesberg landfill, a former contaminated site was cleaned and renatured for this purpose. About one million cubic metres of excavated material was moved to this site. The remaining part of the tunnel spoil of about one million cubic metres from the west section was used to build noise protection embankments along the railway line west of the tunnel. The tunnel entrance to the east section, which lies in a sensitive residential area within the municipal area of Vienna where space is scarce, is situated underground. Particular care was taken in the planning and design of the excavation operations within the densely populated area of the east section to minimise both noise nuisance and ground settlements. The tunnel excavation and lining operations were completed and railway works started in the spring of 2010. A slab-track system jointly developed by Porr and Austrian Railways is used for the tracks. The new railway line is scheduled to start operation at the end of 2012.
The implementation of the project faced not only technical challenges such as conventional tunnelling with a large cross section and under shallow cover in a built-up region, construction of shafts and caverns as well as use of two 10.6m diameter tunnel boring machines, but also a number of additional constraints resulting from the need to minimise the environmental impact.