Tunnel in urban site - Lausanne Metro m3 Section Casernes – Blécherette

The objective of this scientific paper is to present the m3 metro project, in particular the Casernes-Blécherette section. The article is a summary of the final project development based on the technical report [1]. It includes the geological and hydrogeological context, the general concept of the structures, the execution methods, the inventory of constraints, the dimensioning of the structures and its elements, the typical excavation profiles and the normal profiles of the tunnels, the excavation and support profiles and the normal profiles of the stations, as well as the installation and logistics of the construction site. The urban context and the requirement of the client to maintain at least one traffic lane in each direction impose a top-down construction of the stations: This method consists in retaining walls in secant piles and a cover slab before excavation of the station. The tunnel will be built as a cutand- cover, near the stations where the ground cover is not sufficient, and as an underground tunnel.