Tunnel under construction

Maintenance-free tunnel built to last 100 years

Joanne McIntyre - 20 April 2017

The Holmestrand station is a prestigious development and part of a high speed railway development by NSB AS, the Norwegian state-owned railroad company, that will create a triangle from Oslo to south Norway and then up to Bergen. The use of duplex in the construction will ensure that it remains maintenance free and fully functioning for at least a century.

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Mrs Joanne McIntyre
Joanne McIntyre is the Editor in Chief of Stainless Steel World magazine, and Conference Coordinator for the Duplex Seminar & Summit.
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The Holmestrand station is part of a new high-speed rail system that will transform Norway’s transport infrastructure. The use of low weight and ‘maintenance free’ duplex stainless steel was chosen for critical ‘hanger’ components based on an entirely new hollow bar design. The hangers will support a section of the 12 km long high speed rail tunnel which includes the station. Inside the tunnel are two parallel tracks that will, in the
future, enable two high-speed trains to pass each other at maximum speeds of 250 km per hour – something which has never been performed before.

Benefits of duplex

The choice of duplex was specified by Ramboll, the engineering company for the project, after it was determined that the construction must remain maintenance free for 100 years. It is estimated that more than four million movements will occur in the tunnel
during that time. The railway is also the first of its kind to be situated inside a mountain, which places extra demands on the steel.

“Duplex stainless steel is an ideal material in situations where high corrosion and fatigue resistance, and high mechanical strength, is required, and Sanmac® 2205 could also provide excellent machinability. Duplex stainless steel is unbeatable if you need these properties,” said Viktor Stefansson, Global Product Manager for Hollow Bar at Sandvik. Construction on the Holmestrand station could only commence after the hangers – from which the rest of the structure is hung – were mounted. Sandvik helped control the logistic planning for the tunnel to a very tight schedule.

“When Sandvik came into the picture, they showed craftsmanship and were trustworthy, being the right partner,” said Jan Beckers, Managing Director of Hollandia, the company responsible for fabrication and erection of the steel. Construction company HENT has managed the overall station building project. Support from the Swedish manufacturer that was integral to the project included recommending improved dimensions for the hanger components.

This guaranteed optimal use of the material and saved Hollandia more than 100 tonnes of material. Sandvik supplied the components cut to length and on time according to a tight schedule. Dyon Hermsen, Dutch Area Sales Area Manager, Sandvik, who alongside the Production Unit worked closely with the customer, said: “We had seven weeks from order to delivery. As the construction was one of the first activities before continuing with the station, the hollow bar had the highest prioritization. There was no room for mistakes so we had the whole chain – R&D, planning and production – with us.” Sandvik anticipates similar projects for its duplex stainless steel hollow bar after successful completion of the Holmestrand station, the planned opening of which is at the end of 2016.

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