Mick Bergh
Director Inshore
The Söderström tunnel forms a key part of the Citybanan railway development in Stockholm. This 340-metre-long immersed tunnel is located between Riddarholmen and Södermalm and connects the rock tunnels on either side of Lake Riddarfjärden. It is an integral section of a 6-kilometre twin-track railway system designed to improve capacity through the city.
The structure consists of three prefabricated tunnel elements, two short cut-and-cover sections, and a joint house. Due to the limited water depth and specific site conditions, the tunnel was constructed as a unique sandwich structure, combining concrete with a double steel shell, a rare solution in Europe. Because of the soft soil layer above the bedrock, the tunnel was partially installed above the lakebed, supported by three pile groups.
Following immersion, the tunnel elements were connected using prestressing techniques. The structure is fixed at the southern end in the rock at Södermalm, while the northern end remains flexible at the joint house, allowing for controlled movement.
DCN Diving was contracted to execute all diving-related activities, both prior to and during the installation of the tunnel elements. The scope of work included engineering support, preparation of method statements, underwater concreting, installation and removal of subsea lifting structures and full dive support throughout the project.
Director Inshore
© 2024 DCN Diving. All Rights Reserved, DCN Diving B.V.
