The work and the technique: the Cityringen Metro, Denmark

Copenhagen, a city that can boast the most developed public mobility system in Europe, with Cityringen, has built an urban ring in its city centre, with the aim of becoming the world's "greenest" capital. To carry out the project — designed and built by Webuild through its subsidiary Copenhagen Metro Team — the ability to operate within a densely populated urban centre proved essential, minimising disruption to traffic and residents, while reducing risks to nearby historic buildings.

Excavations were mainly carried out in limestone rock with varying fracturing degrees. And, in some sections, in loose soils of predominantly glacial origin of varying grain sizes. The tunnel was lined with prefabricated concrete segments.

The project includes four ventilation, extraction and TBM assembly shafts, and a cut and cover made ramp connecting to the maintenance and control centre. 

Stations and shafts were made with the bottom-up method, except for the Marmorkirken station and the new Havnenholmen shaft, which were the most challenging interventions to carry out: the first, built with the top-down method, due to how close it is to the 18th century Frederiks Kirke church (Marmorkirken); the second, due to the fact that the tunnel runs under the historical 19th century Danish mall, Magasin du Nord, at Kongens Nytorv.