Thirty-nine days of closure are almost behind us. In the Yvelines (78), the RER C is returning to normal traffic this dimanche 23 août 2026 between Paris and Versailles. The week, though, is not the one that signals a generalized return to normalcy: the ligne J will, in turn, suspend its service for the entire weekend of 22-23 August between Paris and Mantes-la-Jolie, and several local bus networks remain disrupted.
Here's a look at what actually changes for Yvelines residents: reopened stations, substitute buses, and, above all, the local networks (SQY, Mantois, Saint-Germain Boucles de Seine, Grand Versailles) that are often left out of transport roundups.
The RER C works wrap up on the evening of Saturday, August 22, with normal service resuming on Sunday, August 23, according to Île-de-France Mobilités. The Versailles-Château-Rive-Gauche, Saint-Quentin-en-Yvelines, Viroflay-Rive-Gauche and Chaville-Vélizy stations will be served again.
The issue at stake is replacing 4 km of track and catenaries in a century-old tunnel that has never been fully renovated. Until now, the alternatives have been lines N or U from Versailles-Chantiers, or line L from Versailles-Rive-Droite.
The tram-train T13 is also returning to normal service from August 22. Until then, the only remaining disruption is a nightly closure after 10 p.m. between “Les Portes de Saint-Cyr” and “Saint-Cyr,” with a replacement bus.
In Mantes-la-Jolie, Track 15 is set to reopen this week: SNCF Transilien announces the end of the weekend cap of three trains per day to Épône-Mézières, as part of the EOLE project to extend the RER E.
Another pause in service: on the lines N and U, the weekday evening disruption on the Rambouillet branch, linked to the Versailles-Rambouillet modernization project, will take a break from August 17 to 21 before resuming at the end of August.
Not everything is back to normal yet. On the J line, no trains have operated between Les Mureaux and Mantes-la-Jolie since August 15-16, and this disruption will continue until September 4, with replacement buses running continuously.
Over the weekend of August 22-23, the disruption widens: there will be no trains between Paris-Saint-Lazare and Mantes-la-Jolie via Conflans-Sainte-Honorine, nor to Ermont-Eaubonne, according to a SNCF Transilien statement dated August 5.
Trains bound for Pontoise are being diverted via Conflans-Fin d'Oise, which becomes the first stop after Paris-Saint-Lazare. On Sunday, August 23, from 9:50 p.m., the Paris-Saint-Lazare–Pontoise service will be suspended entirely.
Buses link Conflans-Fin-d'Oise to Mantes-la-Jolie (all stops), Argenteuil to Conflans-Fin-d'Oise, and Asnières-sur-Seine to Ermont-Eaubonne. For Ermont-Eaubonne and Sannois, the H line from Paris Gare du Nord remains the recommended alternative.
That is the area where users say they receive the least information. Four Yvelines bus networks are also dealing with their share of disruptions this week, sometimes directly tied to railway work, sometimes for unrelated reasons.
In Saint-Quentin-en-Yvelines, six lines of the SQY network (5104, 5105, 5134, 5143, 5144 and 5145) have been running on an adapted service since July 27, due to the tunnel at Saint-Quentin station being closed for RER C works.
The underground stop at the station has been temporarily moved to “Gare de Saint-Quentin – Avenue des Prés,” and several stops are no longer served. This situation is expected to end with the reopening of the RER C on August 23.
In Mantes-la-Jolie, a much longer disruption kicks off this week. According to the Bus Mantois network, line 5427 will no longer stop at three stations starting Monday, August 17, for about sixteen months, due to long-term roadworks.
The affected stations are "Mantes Station-Victor Hugo," "Duhamel," and "Normandie." The proposed replacement stops are "Mantes Station-Calmette" and "Division Leclerc."
In the Saint-Germain-en-Laye area, RTE works on the RD7, between Le Pecq and Marly-le-Roi, are set to run until August 28. The underground electrical connections renewal project, underway since July 6, requires one-way traffic.
Several local bus lines in the CASGBS network (Saint-Germain Boucles de Seine) are diverted, and some stops remain out of service all week. The practical guide drawn up in the early weeks of the RER C closure still holds for planning trips through Sunday.
The Versailles Grand Parc network, commonly known as Phébus, has published a summer works plan announcing service disruptions and reduced frequencies on several lines, particularly those linked with the RER C, to accommodate the expected shift in passengers.
The line-by-line details for this particular week have not been definitively confirmed: sector users would do well to check their line before setting off.
Île-de-France Mobilités and SNCF Connect keep the replacement bus timetables up to date in real time, a handy habit when stops change from day to day. For Ermont-Eaubonne or Sannois, during the August 22–23 weekend shutdown, Line H from Paris Gare du Nord remains the simplest workaround.
August 23 marks a real turning point: 39 days of RER C disruption are over, the T13 is running normally, and the Rambouillet branch of lines N and U enjoys a final disruption-free weekend before the end of August.
But the back-to-school period is approaching, and with it a new transport project in Yvelines: a scheduled outage on the RER A between Sartrouville and Poissy has already been announced from August 30 to October 1, in the evenings from 9:45 p.m. It’s a reminder that in Yvelines, a transport worksite never waits long before the next one is announced.
Dates and Opening Time
From August 22, 2026 to August 23, 2026
