The contract, worth almost €320m (£267m), includes the construction of 8km of tunnel, nine stations and four associated emergency shafts.
The team also includes Vinci subsidiaries GTM Ouest and Botte Fondations as well as Spie Batignolles TPCI, Spie Fondations and Legendre Génie Civil.
The tunnel boring machine will start up at the end of 2014; delivery is scheduled for February 2018. Some 500 people will work on the site, including about 60% from the Rennes area, employed by the consortium’s local companies, suppliers and subcontractors or hired particularly through social integration programmes.
Vinci companies also worked on Line A of the Rennes metro.