Today, Stadelhofen station in the heart of Zurich is already one of the busiest railway stations in Switzerland. With around 80,000 passengers and 770 trains a day, it makes an important contribution to public transport. At the same time, however, with its three tracks it is also a bottleneck in the Zurich S-Bahn network.

As part of the STEP AS35 programme (Strategic Development Programme for Railway Infrastructure Expansion Step 2035), plans are underway to expand the station. The aim is to build a fourth track in the station and a second Riesbach tunnel to Zurich Tiefenbrunnen. This will increase the capacity of Zurich Stadelhofen station by 50 per cent.

SBB AG was commissioned by the federal government to carry out a feasibility study at the end of 2016. The preliminary project phase began in autumn 2017. From this planning phase onwards, all elements of the project will be planned and examined. Drees & Sommer Switzerland is supporting SBB's overall project management as project controller.