The event was attended by the mayor of Paris Mrs Anne Hidalgo, president of Ile-de-France regional council Mr Jean-Paul Huchon, Paris Transport Authority (RATP) CEO Mr Pierre Mongin and Ile-de-France transport authority (Stif) president Mr Patrick Devedjian.
The extension will relieve the heavily congested section of Line 13 north of St Lazare and will have capacity to carry up to 40,000 passengers per hour. It will interchange with RER Line C, Transilien (suburban) Line L, and light rail Line T3b, which is being extended from Porte de la Chapelle to Porte d'Asnieres.
The €1.38bn project includes the construction of four new stations, Pont Cardinet, Porte de Clichy, Clichy Saint Ouen RER and Mairie de Saint Ouen.
RATP and Stif ordered 14 MP05 rubber-tyred driverless trains from Alstom in 2012 to expand the Line 14 fleet in readiness for the opening of the extension in 2017.
Line 14 will ultimately become part of the Grand Paris express metro network and further two further new sections are planned which will increase the total length of the line to 30km, extending it north to St Denis Pleyel and south to Orly Airport via Villejuif.