EOLE ( Est Ouest Livraison Express): this is an Ile-de-France project we've been hearing about for several years now. Declared to be in the public interest on January 31, 2013, it involves extending the RER E westwards to Mantes-la-Jolie in the Yvelines department. With a total of 55 kilometers of new or upgraded track, the new RER E line will offer users an alternative to the RER A, whose central section is regularly saturated. In future, thanks to this extension, journey times between Mantes-la-Jolie and La Défense will be reduced to 40 minutes, compared with 55 minutes at present.
Last year, two milestones were reached, with the opening of three new stations (Neuilly-Porte Maillot, La Défense and Nanterre-la-Folie) in May 2024, but with off-peak service only. It wasn't until December 2024 that the extension to Nanterre-la-Folie reached cruising speed, with regular all-day service and no need to change trains.
What's next? RER line E will soon be extended once again to reach Mantes-la-Jolie, the new terminus and final stage of the EOLE project. Involving the renovation and modernization of the existing 47 km of track between Nanterre and Mantes-la-Jolie, this RER E extension will serve the stations at Houilles - Carrières-sur-Seine (connections with RER A and Transilien line L), Poissy (connections with RER A and T13), but also Villennes-sur-Seine, Vernouillet-Verneuil, Les Clairières de Verneuil, Les Mureaux, Aubergenville-Elisabethville, Epône-Mézières, Mantes Station and finally Mantes-la-Jolie (connections with Transilien lines J and N).
So, when is the RER E extension to Mantes-la-Jolie scheduled to go into service? Unfortunately, work on the extension is still behind schedule. According to Le Parisien and Carrières Mag, full commissioning of the extension is now postponed"at best until the end of 2029". On the other hand, a"partial operation phase involving just a few trains" is scheduled to start in January 2027.
