The plan was to lengthen the Metro Line 12 in northern Paris between La Porte de la Chapelle and Mairie d`Aubervilliers. From the Porte de la Chapelle, the extension will make it possible for the city center of Aubervilliers to be reached in under ten minutes. To this end, the S-499 Earth Pressure Balance Shield of a 9,150-mm diameter started working in October 2009. Its tunnelling operation took it through chalk, sand and limestone over a length 3,800 meters. On December 5, 2011, the large-diameter machine arrived at the target shaft.
Extension Line 12 (French)