Monaco offshore extension

In 2019, the Principality of Monaco embarked on an offshore urbanisation project with the creation of a six-hectare eco-district. The maritime infrastructure, built by Bouygues Travaux Publics, consists of a platform surrounded by a protective belt made up of 18 reinforced concrete caissons placed on an underwater embankment made up of quarried material and compacted into seascapes.

To carry out this offshore extension, Bouygues Travaux Publics developed new and innovative construction methods, with the aim of reducing the impact of the project on the environment and preserving the Principality's natural marine heritage.

Standing 26 metres high and weighing 10,000 tonnes, the 18 caissons were built in Marseille in a structure that is unique in France: a 4,600-tonne floating and submersible dock, the Marco Polo.

Each caisson has an absorption chamber with a series of openings on the sea side, known as Jarlan slots, which break wave power and absorb swell energy.