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Copenhagen’s Lille Langebro Swing Bridge

The Danish city of Copenhagen has many opening bridges due to its low lying nature and its active waterways. The Lille Langebro (Little Long bridge) pedestrian and cycle double swing bridge is the latest addition to the Copenhagen waterfront. The 160m long bridge located at Vester Voldgard consists of five spans, the centre two rotate to create a 35m opening to allow marine craft to pass the bridge.

Key facts

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Location

Copenhagen, Denmark

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Client

Realdania for Københavns Kommune

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In Partnership with

Buro Happold, Wilkinson Eyre, Niras, Urban Agency, Speirs & Major

We worked together with Buro Happold, Wilkinson Eyre and Niras to produce the design of this architecturally striking and technically challenging bridge. Our role was to produce the detailed concept design of the operating equipment which allowed the architectural vision to be realised whilst also ensuring that the operating equipment, used to control the 2 central moving decks, is reliable and maintainable.
The two moving spans are mounted on large diameter slewing bearings which have integral teeth. These teeth engage with pinions, driven by four 15kW electric motor gearbox units, resulting in the span rotation. The bridge operating cycle takes 109 seconds to open and 144 seconds to close.

Lille Langebro moment connection tension

Lille Langebro moment connection compression

A key area of innovation is the moment connection at the joint between the two moving spans. The connection allows the structure to be kept very shallow and slender in elevation – true to the architect’s vision – whilst also allowing the bridge to thermally expand and contract. Our Engineers developed a system which that utilises a pair of hydraulic cylinders located in the two main structural beams. One cylinder provides a compressive force and the other a tensile force. Together they push and pull on the ends of the spans to transfer the compressive and tensile forces that occur as live load is applied. The clamping action also means the bridge is much stiffer and less prone to deflections and vibrations than if it were simply pinned in the middle.

The bridge is controlled from the existing and historic copper clad control room for the bridge’s bigger brother, the Langebro bridge. This control position gives an excellent direct line of sight of both the marine channel and also the traffic passing over the bridge. Prior to opening the pedestrian and cycle traffic is cleared from the bridge using a combination of lights and sounders before barriers lower to control the movement of bridge traffic.