Grand Paris Express: here is the start date for putting the first stretch of Line 18 into service.

It will be the first of four new Grand Paris Express lines to be inaugurated, ahead of lines 15, 16 and 17. Scheduled initially for 1 October 2026, the opening of the first stretch of Line 18 is now set for 30 November. From that date, passengers will be able to travel between Massy–Palaiseau and Christ de Saclay stations in Essonne. Line 18, the first entirely new metro line in Île-de-France in thirty years, is expected to ease the daily lives of the many students, researchers and workers who live, study or commute nearby.

Due to the delay on line 15 South, the line 18 will be the first of the four new lines of the Grand Paris Express to be inaugurated. But line 18 will also launch later than planned. While its opening was originally set for 1 October 2026, the first section of the line 18, between Massy-Palaiseau and Christ de Saclay, will finally begin carrying passengers from 30 November 2026. This is what our colleagues at the Parisien report. The following year, the stretch between Massy-Palaiseau and Orly airport is also slated to enter service. Finally, we will have to wait until 2030 to connect Christ de Saclay to Versailles - Chantiers.

Construction work began in 2020, and the metro’s first tests kicked off on December 18. A first train subsequently ran over the viaduct, marking a decisive milestone for the commissioning of Line 18. For the occasion, teams from the Société des Grands Projets, in charge of the design and construction of the Grand Paris Express, were on hand to “orchestrate this operation carried out for the first time on an above‑ground structure of the Grand Paris Express,” as stated in a press release.

Ligne 18 : la première des quatre nouvelles lignes du Grand Paris Express à être inaugurée en 2026 — Premier roulage de la ligne 18 sur le viaduc ©Gérard Rollando / Société des grands projets

During this crucial phase, the ability of a stalled train to be pulled by another was tested. Braking and acceleration drills up to 30 km/h were also carried out. Following the famous automatic-mode metro operation, launched at the start of the year, there will be the long-awaited dry run, ahead of Line 18’s first service, running from Massy–Palaiseau in Essonne to Christ de Saclay, scheduled for 30 November 2026.

It is recalled that the Line 18 of the Grand Paris Express will run through several towns in the Essonne and the Yvelines, including Saclay, Orly, Antony, Massy, Saint-Quentin-en-Yvelines, and Versailles. In total, 10 stations will be served by Line 18, and a journey from Versailles to Paris-Orly Airport will take about 30 minutes.

At the opening of the first section, future riders will be able to alight at Christ de Saclay, Université Paris-Saclay, Polytechnique in Palaiseau, and Massy - Palaiseau, connecting with RER B and C, Transilien Line V, the T12 tram, and also the Massy TGV station. It’s worth noting that Line 18 will feature a 14 km aerial stretch between Palaiseau and Saclay, made possible by a 6.7 km viaduct — the longest in France.