Nord/Süd-Metrolinie Amsterdam - Schild Transfer System (STS)

North/South Metro Line Amsterdam - Shield Transfer System (STS) - a technical innovation for the construction of a metro tunnel in urban environment

The construction of the North/South metro line in Amsterdam, the Netherlands, is a challenging tunnelling project in an urban environment. Innovation and creativity are needed to enable tunnelling with a mixed shield TBM, which considers the existing ground conditions, the narrow station structures and the densely built-up areas on the surface. A sealing block in front of the station and lip sealing or a short sealing pot within the station are usually used for conventional launch and arrival situations of mixed shield tunnelling in pressurized groundwater conditions. They represent a redundant system for launch and arrival situations. Due to geometric reasons, these sealing systems cannot always be used in the construction of the Metro Line in Amsterdam. Therefore, the innovative Shield Transfer System (STS) was developed. The big advantage of which is that all the required launch and arrival sealing systems can be installed inside the stations. The transfer of the TBM through the stations, including the lifting over the steps (heights of up to 1.65 m), is an essential feature of the STS. The following article describes the construction of the STS from a static and constructional point of view and is explaining the differences with respect to conventional launch and arrival situations.