S21 – Suburban railway (S-Bahn) bridge

Architecture
Ingenhoven Architekten, Düsseldorf/Germany

Planning time
2011 – 2020

Construction time
2014 – 2025

Services by Werner Sobek
Structural engineering (WP 3 – 5 + 8)

Client
DB Projektbau GmbH, Stuttgart/Germany

A number of architectural alterations are being made to the state capital of Stuttgart as part of the Stuttgart-Ulm railway project. These changes include the construction of a new, underground, eight-track through station with a train shed that measures approximately 420 metres long and 80 metres wide. The floor of this new train shed crosses an existing suburban railway (S-Bahn) tunnel. Laid out in the same orientation as the station itself, the floor slab in this area is designed to act as a prestressed bridge construction that spans a distance of around 30 metres between bored pile walls situated either side of the S-Bahn tunnel. This stops loads from the new train shed being placed on the existing tunnel structure below. The bridge is also prestressed with internal, non-composite tendons to allow it to support two pillars known as ‘chalice supports’ that transfer loads of approximately 60 MN from the shell roof above. The planners’ task is made more difficult by the fact that the bridge has to accommodate four large openings for stairways leading into the S-Bahn tunnel. Although the faces of the bridge include maintenance walkways with adjacent engineering rooms, spatial constraints mean that inspectors can only gain partial access to certain sections of the structure. In order to compensate for this limitation, the bridge is being measured using tighter tolerances than usual and fitted with a complex monitoring system. This permanent monitoring set-up will work alongside the innovative prestressing procedures developed for the railway project to ensure that the construction can provide unlimited service over a long period of time.

Images
Ingenhoven Architekten, Düsseldorf/Germany
Werner Sobek, Stuttgart/Germany