Disruptions on line J Paris - Mantes via Poissy and Issou Porcheville on November 8 and 9, 2025

On November 8 and 9, 2025, Transilien line J will be interrupted between Paris Saint-Lazare and Mantes-la-Jolie via Poissy. There will also be disruption on the Issou-Porcheville route throughout the weekend, with replacement buses in place.

Transilienline J, which links Paris Saint-Lazare to several destinations in the western Paris region, will be experiencing major disruptions on the weekend of November 8 and 9, 2025. Commuters in the Yvelines region will have to plan accordingly, as there will be no trains running between Paris Saint-Lazare and Mantes-la-Jolie via Poissy, or between Issou-Porcheville and Mantes-la-Jolie during these two days. This modernization work is designed to improve the quality of the rail network, but will necessitate a complete halt to traffic on these strategic routes.

Which roads are affected by the work?

The disruptions will affect two major routes on line J. Firstly, the Paris Saint-Lazare - Mantes-la-Jolie route via Poissy will be completely closed throughout the weekend. Secondly, the Paris Saint-Lazare - Mantes-la-Jolie branch via Conflans-Sainte-Honorine will be affected between Issou-Porcheville and Mantes-la-Jolie. This line, which carries 260,000 passengers every working day, is an essential link between Paris and the western part of the Paris region, particularly to towns such as Houilles-Carrières-sur-Seine, Poissy and Conflans-Sainte-Honorine.

What alternative solutions are planned?

To compensate for these disruptions, SNCF and Île-de-France Mobilités are introducing several alternatives. SNCF replacement buses will run between Les Mureaux and Mantes-la-Jolie, as well as between Issou-Porcheville and Mantes-la-Jolie, serving intermediate stations. Regular bus routes will be reinforced, notably bus 7821(formerly Express A14) between La Défense and Les Mureaux, bus 7820 between La Défense and Mantes-la-Jolie, and bus 6543 (formerly bus 43) between Poissy and Les Mureaux.

How do you plan your journey this weekend?

If you have to travel on these routes on November 8 and 9, we strongly advise you to allow for an extended journey time. Replacement buses generally take longer than regular trains, and frequency may be different. Check the Île-de-France Mobilités and SNCF Connect applications regularly for real-time updates. The Transilien website also offers a works calendar to help you anticipate future disruptions. For full details of these specific works, see the official announcement on the line J blog.

Why is this work necessary?

These interruptions, though restrictive, are part of a program to modernize the Paris region rail network . Mantes-la-Jolie station, served by Transilien lines J and N, as well as by Intercités and TER trains to Normandy, is a strategic rail hub. The work will improve train regularity, traffic safety and passenger comfort over the long term. This modernization is all the more crucial as the line will eventually accommodate the extension of the RER E to Mantes-la-Jolie.

In short, if you're planning to take line J this weekend of November 8 and 9, 2025, plan ahead and don't hesitate to explore alternatives such as carpooling or other transport routes. SNCF teams remain available in stations to guide you and answer your questions.