Works in the southern sector of Île-de-France: disruptions and alternative routes

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On this page, find the details by period of disruptions related to the works on the RER B and C lines (south and south-west of Paris), as well as the alternative routes to choose to get around.

Île-de-France has been divided into 5 sectors (South, East, Centre, North-East and North-West) to better understand the impact of disruptions on the public transport network on a regional scale. During the different periods, alternative routes may save time compared to the usual alternative route.

To simplify your travels

One month before the start of the work, the Île-de-France Mobilités route planner (available on our website and smartphone application) will take into account closures and disruptions and will allow you to anticipate your journeys.

Closure for works and alternative routes: the recap by period

Work information from 15 July to 24 July 2026

1. Reminder of closures

From 15 to 24 July 2026, the RER C is closed between Gare d'Austerlitz and Pontoise, Saint-Quentin-en-Yvelines and Versailles-Château.

2. Alternative routes to take during the period

From 15 to 24 July 2026, the RER C is closed between Gare d'Austerlitz and Pontoise, Saint-Quentin-en-Yvelines and Versailles-Château.

Take alternative routes to reach Paris.

To get to Paris from Saint-Quentin-en-Yvelines, Saint-Cyr, Versailles-Chantiers, Vélizy, and Viroflay Left Bank

  • Take the U line to Versailles-Chantiers then the U line to La Défense
  • Or take the N line to Versailles-Chantiers and then the N line to Gare Montparnasse

To get to Paris from Versailles

  • Take the L line at Versailles - Rive Droite towards Gare Saint-Lazare

To get to Paris from Meudon Val-Fleury

  • Take the N line at Meudon towards Gare Montparnasse

To get to Paris from Issy

  • Take metro 12 to Mairie d'Issy towards Paris
  • Or take the T2 tram at Jacques-Henri Lartigue towards Paris

To reach the Palace of Versailles from Paris

  • Take line N at Gare Montparnasse to Versailles-Chantiers
  • Or take the L line at Gare Saint-Lazare to Versailles - Château

Work information from 25 July to 6 August 2026

1. Reminder of closures

From July 25 to August 6, 2026:

  • The RER B is closed from Gare du Nord to Bourg-la-Reine.
  • The RER C is closed between Gare d'Austerlitz and Pontoise, Saint-Quentin-en-Yvelines and Versailles-Château.

2. Alternative routes to take during the period

From 25 July to 6 August 2026, closures will take place on the RER B and C

Take alternative routes to reach Paris.

For alternative routes to the RER C, refer to the period from 15 to 24 July 2026.

From the stations located between Saint-Rémy-lès-Chevreuse and Massy-Palaiseau:

  • Take line B to Massy-Palaiseau > line V to Versailles-Chantiers > line N to Montparnasse
  • Or take line B to Massy-Palaiseau > line V to Versailles-Chantiers > line U to La Défense
  • Or take line B to Massy-Palaiseau > RER C to Pont de Rungis > metro 14 to Paris

From the stations located between Massy-Verrières and Antony

  • Take line B to Antony > OrlyVal line to Orly Airport > metro 14 to Paris - Orlyval is accessible at no extra cost for monthly/annual/ImaginR Navigo subscribers
  • Or take line C to Pont de Rungis > metro 14 to Paris

From the stations located between Antony and Parc de Sceaux

  • Take line B to La Croix de Berny > the Tvm bus to Chevilly-Larue > metro 14 to Paris
  • Or take line B to Antony > Orlyval line to Orly Airport > metro 14 to Paris. Orlyval is available at no extra cost for monthly/yearly/ImaginR Navigo subscribers
  • Or take the RER B relay buses which will serve (direct or semi-direct) Bourg-la-Reine <> Porte d'Orléans

From the stations between Robinson/Bourg-la-Reine and Gentilly

  • Take the RER B relay buses which will serve (direct or semi-direct) Bourg-la-Reine <> Porte d'Orléans
  • Or take the regular buses to metros 4, 13 and 14

Work information from 7 to 16 August 2026

1. Reminder of closures

From August 7 to August 16, 2026:

  • The RER B is closed between Gare du Nord and La Croix de Berny/Robinson.
  • The RER C is closed between Gare d'Austerlitz and Pontoise, Saint-Quentin-en-Yvelines and Versailles-Château.

2. Alternative routes to take during the period

From 7 to 16 August 2026, closures will take place on the RER B and C

Take alternative routes to reach Paris.

For alternative routes to the RER C, refer to the period from 15 to 24 July 2026.

From the stations located between Saint-Rémy-lès-Chevreuse and Massy-Palaiseau:

  • Take line B to Massy-Palaiseau > line V to Versailles-Chantiers > line N to Montparnasse
  • Or take line B to Massy-Palaiseau > line V to Versailles-Chantiers > line U to La Défense
  • Or take line B to Massy-Palaiseau > RER C to Pont de Rungis > metro 14 to Paris

From the stations located between Massy-Verrières and Antony

  • Take line B to Antony > OrlyVal line to Orly Airport > metro 14 to Paris - Orlyval is accessible at no extra cost for monthly/annual/ImaginR Navigo subscribers
  • Or take line C to Pont de Rungis > metro 14 to Paris

From the stations located between Antony and Parc de Sceaux

  • Take line B to La Croix de Berny > the Tvm bus to Chevilly-Larue > metro 14 to Paris
  • Or take line B to Antony > Orlyval line to Orly Airport > metro 14 to Paris. Orlyval is available at no extra cost for monthly/yearly/ImaginR Navigo subscribers
  • Or take the RER B relay buses which will serve (direct or semi-direct) Bourg-la-Reine <> Porte d'Orléans

From the stations between Robinson/Bourg-la-Reine and Gentilly

  • Take the RER B relay buses which will serve (direct or semi-direct) Bourg-la-Reine <> Porte d'Orléans
  • Or take the regular buses to metros 4, 13 and 14

Work information from 17 to 22 August 2026

1. Reminder of closures

From 17 to 22 August 2026, the RER C is closed between Gare d'Austerlitz and Pontoise, Saint-Quentin-en-Yvelines and Versailles-Château.

2. Alternative routes to take during the period

From 17 to 22 August 2026, the RER C is closed between Gare d'Austerlitz and Pontoise, Saint-Quentin-en-Yvelines and Versailles-Château.

Take alternative routes to reach Paris:

To get to Paris from Saint-Quentin-en-Yvelines, Saint-Cyr, Versailles-Chantiers, Vélizy, and Viroflay Left Bank:

  • Take the U line to Versailles-Chantiers then the U line to La Défense
  • Or take the N line to Versailles-Chantiers and then the N line to Gare Montparnasse

To get to Paris from Versailles

  • Take the L line at Versailles - Rive Droite towards Gare Saint-Lazare

To get to Paris from Meudon Val-Fleury

  • Take the N line at Meudon towards Gare Montparnasse

To get to Paris from Issy

  • Take metro 12 to Mairie d'Issy towards Paris
  • Or take the T2 tram at Jacques-Henri Lartigue towards Paris

To reach the Palace of Versailles from Paris

  • Take line N at Gare Montparnasse to Versailles-Chantiers
  • Or take the L line at Gare Saint-Lazare to Versailles - Château