M4 extension to Bagneux

The M4 provides transport services between Porte de Clignancourt and Mairie de Montrouge. The highly-awaited extension south of Paris, from Mairie de Montrouge to Bagneux, is scheduled to start-up service by mid-2021.

The M4 southern extension is part of efforts to improve public transport services in the inner suburbs of the Greater Paris region.

Useful information:

  1. Département 92
  2. Connection with the future M15


  • Trains will run every 1 minute and 45 seconds, during peak hours.
  • Easier, direct access to Paris from the cities of Montrouge and Bagneux.
  • Easier connections with all RER lines, tramway T3a and virtually all of the metro lines. Ultimately, the M4 will connect with the future M15 of the Grand Paris Express, at the Bagneux station.
  • The extension will also provide improved accessibility for persons with reduced mobility (escalators and elevators).

Key figures

2 new stations will be created to serve the towns of Montrouge and Bagneux, and 37,000 passengers are expected to use the extended M4 daily.
Extension M4 - Platform - RATP
Extension M4 - Platform - RATP


  • October 2011: pre-project draft designs approved by the STIF board of directors
  • January-February 2012: new public hearings
  • December 2012: declaration of public utility
  • Mi-2015: construction work begins
  • By mid-2021: start-up of service

Project players

STIF (transport organising authority for the Île-de-France region): as the entire project’s supervisor, STIF oversees compliance with the programme, as well as the calendar and costs.

Project costs and financing

The cost of the project is estimated at 380m € (2011 value).

The French State, the Île-de-France Regional Council and the Hauts-de-Seine General Council are participating in project financing as follows:

Hauts-de-Seine General Council: 14.3%

French State: 25.7%

Île-de-France Regional Council: 60%.

Metro Line 4