[Work is progressing] Extension of metro line 12

The excavation of the two future stations is taking place in a very special environment. As the soils of Aubervilliers are bathed by the water table, the project teams had to find a solution to stabilise the ground during digging to avoid any water infiltration. The ground freezing technique was chosen to respond to this problem.

At a depth of 20 metres, 3 tympanums (junction between the tunnel and the stations) were built: the north tympanum of the Aimé Césaire station and the two tympanums of Mairie d'Aubervilliers. From inside the tunnel, nearly 250 boreholes were drilled in order to be able to insert 240 interconnected freezing tubes (80 tubes per eardrum) into the subsoil, maintained 24/7 at -35°. The frozen ground is more stable, which allows the construction of the bottom of the station and the final connecting walls of the tympanums and the tunnel.

This veritable "ice shield" will be maintained until the end of 2017 for the Aimé Césaire resort and the beginning of 2018 for the Mairie d'Aubervilliers, until this phase of work is completed. Then it will be time to carry out the interior design and equipment of the stations with a view to putting them into operation.

Find the whole process in pictures in this video:

The Project at a glance

Following a first extension between Porte de la Chapelle and Front Populaire inaugurated in 2012, 3 km and 2 new stations are being built: Aimé Césaire and Mairie d'Aubervilliers. This new extension will make it possible to place the centre of Aubervilliers less than 10 minutes from Paris and to better serve the Plaine Saint-Denis. Nearly 37,000 passengers will use this extension every day, and even more when line 12 connects to the future line 15 of the Grand Paris Express metro by 2025.

Work began in 2016, with commissioning scheduled for the end of 2019.

RATP and Île-de-France Mobilités, respectively the project owner and the organising authority, are leading the project. RATP is responsible for the construction of the extension (infrastructure and transport system) and Île-de-France Mobilités ensures that the project runs smoothly and that costs and schedules are respected.

The project to extend line 12 is financed by the State and the Île-de-France Region for 91.7% and by the Seine-Saint-Denis Departmental Council for 8.3%. The operation and rolling stock of the line are 100% financed by Île-de-France mobilités.

For more information, you can visit the website dedicated to the project: www.prolongement-metro12.fr