The Lille Langebro is the latest movable bridge to be built across Copenhagen harbour. Its elegant design was the result of an international competition and incorporates a complex geometry.
The bridge consists of four sections, two of which rotate in plan to provide the navigation clearance. In order to maintain a slender profile in elevation, an innovative central moment connection has been designed to connect the moving parts together at midspan. The moment connection is achieved via paired hydraulic cylinders located within each of the two bridge box girders mounted to internal diaphragms. The upper mechanisms generate compressive resistance whilst the lower mechanisms generate a tensile force. When engaged in its socket, the compression mechanism also provides shear continuity and vertical alignment of the two moving spans.
The bridge sections were prefabricated entirely off-site and delivered in a completed state by sea. This approach meant improved quality in factory conditions rather than on site, better safety and less susceptibility to weather delays.
The very beautifully detailed swing bridge required close cooperation between all parties to deliver a complex structure to a high standard. It has already become a high profile and important artery for pedestrians and cyclists.