There is something about bridges that make them one of engineering’s most iconic feats. The power to create something over the ocean, to connect two places, to open up new horizons – it’s something which we feel whenever we go over a bridge. From the Golden Gate Bridge in San Francisco and Tower Bridge in London to the Ponte Vecchio in Venice, bridges represent promise and opportunity. Öresund Bridge is a combined railway and motorway bridge across the Öresund strait between Sweden and Denmark.

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Öresund Bridge, Denmark- The Impossible undersea bridge - Sheet1
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Design

The Öresund Bridge designed by the Danish engineering firm COWI was the longest combined road and rail bridge in Europe between 2000-2019. It links two major metropolitan areas: Copenhagen, the Danish capital city, and the Swedish city of Malmö. The bridge spans approximately 8 kilometers (5 miles) from the Swedish coast to the artificial island Peberholm in the middle of the strait.

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The construction of the bridge began in 1995, with its opening to traffic on 1 July 2000. Since its opening, the bridge has served as both a cultural icon and a key piece of infrastructure. Over 230 million people have traveled over the bridge since it was opened, with 141 million of them by car and the rest by train. The cost for the Öresund Connection, including motorway and railway connections on land, was DKK 30.1 billion (~€4.0 billion) according to the 2000-year price index.

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The clarification behind the additional expenditure and complexity related to digging a tunnel for part of the way, rather than raising that section of the bridge, was to avoid interference with air traffic from the nearby Copenhagen Airport, to provide a clear channel for ships in all weather conditions, and to prevent ice floes from blocking the strait.

The Öresund Bridge received the IABSE Outstanding Structure Award in 2002.

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Construction Techniques

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The bridge is nearly half the length of the link with the two 204 m high pylons supporting the 490 m long bridge span across the Flinte channel. These types of bridges are known as a cable-stayed bridge. The bridge is divided into two decks- the railway and motorway run on separate levels with the railway on the lower deck and vehicle traffic on the upper deck.

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Most of the structural elements – the bridge piers and bridge spans of concrete were cast on land and subsequently towed out to the bridge alignment by a large floating crane. The pylons were cast in situ.

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The man-made island of Peberholm links the Öresund Bridge and the tunnel, and it is where the railway and motorway run. The link parallel to each other is adjacent to the natural island of Saltholm further to the north. The 4 kilometers immersed tunnel, Peberholm was constructed from the material dredged from the Öresund seabed to accommodate the bridge piers and the tunnel.

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The mass of the structure is 82,000 tonnes and supports two railway tracks beneath four road lanes in a horizontal girder extending along the entire length of the bridge. The girder is supported at every 140 m (459 ft) by concrete piers, on both approaches to the three-cable stayed bridge section. The two pairs of free-standing cable-supporting towers are 204 m (669 ft) high, allowing shipping with 57 m (187 ft) headroom. The cable-stayed main span is 491 m (1,611 ft) long. To provide specific rigidity, a girder and cable-stayed structure was designed to carry heavy rail traffic, and also to resist large accumulations of ice.

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Vibration caused by several cables in the Öresund Bridge moving under certain wind and temperature conditions were solved with the installation of compression spring dampers in pairs at the center of the cables. Two of these dampers were equipped with laser gauges for ongoing monitoring. Testing, development, and installation of these spring dampers were carried out by the specialists in European Springs.

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Sustainability

The goal of the bridge was to develop the metropolitan cities as one of the cleanest big city-regions in Europe. Environmental factors were considered important not only for the sake of health, quality of life, and sustainability but also for stimulating growth and enhancing the attractiveness of the region. The artificial island of Peberholm not only connects the bridge and tunnel. The island has become a haven for biologists from Denmark and Sweden as its flora and fauna have been allowed to develop freely, undisturbed by man.

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Lund’s Botanical Association has identified more than 500 different species of plants since it’s construction. Although birch, sallow, oak, beech, and willow are found on the island, the strong winds have however restricted their growth. Copenhagen’s Zoological Museum has also collected beetles and butterflies on the island.

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The island serves as a popular breeding ground for birds as well as providing a habitat for the rare green toad. It is also home to rare spiders and insects.

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The Öresund Bridge has created a region with a population of 3.7 million inhabitants. It is now easier than ever to live on one side of Öresund and work on the other. As a result, commuting by car and train has increased dramatically since the bridge was opened, inspiring many Danes to move to Scania. The Öresund Bridge became a cultural icon and infrastructure success in the world.

Author

Trishla Chadha is driven by a persistent desire to learn and to inform. Besides working as a Junior Architect, she is also associated with an International social organization with the aim of empowering women in our society. She is particularly intrigued by the sensitivity of architecture towards nature and people, as well as discovering new aspects that enrich the spatial experience.

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