Øresund Link - the world’s longest immersed tunnel   

In 2000, the Øresund Link opened for traffic.  The major crossing between Denmark and Sweden has turned the Malmö-Copenhagen area into a powerful region. The bridge is, of course, a landmark, but the really interesting piece of engineering is what you don’t see - the tunnel which was the longest immersed tunnel in the world at the time of its inauguration. 

Øresund is one of four waterways that connect the Baltic Sea to the Atlantic Ocean via Kattegat, Skagerrak, and the North Sea, and it is one of the busiest waterways in the world. 

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The link between Denmark and Sweden is a combined railway and motorway, and the bridge runs nearly 8 kilometres from the Swedish coast to the artificial island Peberholm in the middle of the strait. The crossing is completed by the 4-kilometre Drogden Tunnel from Peberholm to the Danish island of Amager. And the tunnel is securing a free passage for ships. Actually approximately 30.000 ships a year uses the Drogden channel. 

Ramboll has designed the tunnel, which consists of two portal constructions of 270 meters and a 3,510 meters immersed tunnel. The invisible tunnel is constructed with two tubes for rail, two tubes for motorway and a fifth tube with service and escape routes.  

The entire immersed tunnel consists of only 20 prefabricated concrete elements. And these are the world’s biggest elements for an immersed tunnel, measuring 176 x 40 x 9 meters and have a weight of 55,000 tonnes. It is an astonishing piece of engineering. 

The use of tunnels to connect people and places is becoming more widespread as environmental issues arise in cities and in the countryside.  

Today, Ramboll offers a full range of engineering services for tunnels and underground structures, including railway tunnels, road tunnels, cyclists and pedestrian tunnels, and tunnels for all types of utility systems. 

We are well-known for our expertise in immersed tunnels and are also a main consultant on the fixed link across Fehmarn Belt, which will then become the longest immersed tunnel in the world. This giant project will consist of even bigger tunnel elements weighing 73,000 tonnes. And the elements will still be immersed with an accuracy of approximately 5 centimetres. 

Fehmarn Belt link was started by the authorities as a bridge, but the final competition was won by Ramboll due to our ability to find an innovative solution that went beyond what the client had requested. 


The beginning of an international journey 

Entering the new millennium, Ramboll had a lower revenue outside Denmark compared to some competitors. No truly international player had entered the Nordic region, but everybody in the consultancy sector expected to see this happen imminently. The large Danish companies were therefore on the lookout for ways to grow in size and increase international revenue. 

Around that time, Ramboll CEO, Flemming Bligaard Pedersen made the prediction that: “within five to ten years, Ramboll is globalised in one form or another.” But the timeframe was to be much shorter. In 2003, Ramboll acquired the Swedish-based Scandiaconsult.  

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Scandiaconsult had throughout the eighties and nineties acquired several companies in the Nordic countries and was already an esteemed international competitor. Suddenly, Ramboll was the biggest consultancy in Scandinavia with more than 4,000 employees. The international ambitions had been kick-started. 

When you look at Ramboll’s 75-year long history, it’s very much a story of developing by joining forces with other companies, big and small, to connect bright minds and gain access to new markets and expertise. The quest has always been to find allies with the same empathetic approach to employees, strong ethics and passion for their profession. Since Scandiaconsult, many mergers and acquisitions have been made. In recent years these include Environ, OBG, Henning Larsen and Web Structures.