In June 2024, users of Paris and Île-de-France public transport watched the extension of Line 14 unfold; the first phase of the Grand Paris Express, this public transport network project steered by the Société des Grands Projets. In total, four new lines are planned to come on stream across Île-de-France between late 2026 and 2031. So where do the works stand? And what are the newly anticipated deadlines following the schedule adjustments announced on September 24, 2026, which chiefly affect Lines 16, 17 and 18?
On the construction front, work continues on the four new lines of the Grand Paris Express. Civil engineering is advancing on the eastern and western segments of Line 15, from Pont de Sèvres to Saint-Denis - Pleyel, and then from Saint-Denis - Pleyel to Champigny Centre. In the southern section of Line 15 and on Lines 16, 17 and 18, site development, equipment installation and testing are progressing in a segment-by-segment rollout.
What's the status on launch dates? If we refer to the provisional timetable, available on the Grand Paris Express site and detailed in the September 24, 2026 press release, the first of the four new lines to be inaugurated should be Line 18. But only an initial segment will be open to passengers, namely the stretch between Massy-Palaiseau and Christ de Saclay stations. While a start of service on October 1, 2026, then from November 30, had been floated, the first stretch of Line 18 is now expected in December 2026.
This initial opening is planned to serve four stations: Massy-Palaiseau, Polytechnique, Université Paris-Saclay, and Christ de Saclay. It will go ahead only after the tests are completed, a dry run is completed, and the required safety approvals are obtained. There is also a budgetary hurdle: on September 29, 2026, Valérie Pécresse warned that a €90 million cut to the expected resources from Île-de-France Mobilités could threaten the opening of new lines, particularly line 18. That warning, reported by Le Parisien, does not come with a replacement date for the December 2026 target.
Then, in autumn 2027, the Line 15 South should be operational between the Pont de Sèvres and Noisy - Champs stations. Initially announced for the end of 2025, its opening has been postponed several times. The target is now set for autumn 2027. As for the Line 18, it is also expected to welcome its first passengers between Massy - Palaiseau and Orly Airport in autumn 2027 as well.
The lines 16 and 17 delays are, however, now confirmed. The Grand Projects Company explains that these two lines share the same automated driving systems as line 15. A window of nine to twelve months is required between the opening of line 15 South and that of the first sections of lines 16 and 17.
In the autumn of 2028, two initial sections are slated to enter service: the stretch from Saint-Denis - Pleyel to Parc du Blanc-Mesnil on Line 16, and the stretch from Saint-Denis - Pleyel to Le Bourget Airport on Line 17. The alignment of Line 16 is being revised: the first opening will no longer extend to Clichy - Montfermeil, as previously announced.
In the fall of 2029, Line 16 is slated to be extended from Parc du Blanc-Mesnil to Noisy-Champs, serving Aulnay, Sevran, Clichy-Montfermeil and Chelles. Line 17, for its part, would be extended from Bourget Airport to Parc des Expositions.
In 2030, the Grand Paris Express will expand with the planned opening of the section between Saclay Christ and Versailles - Chantiers on line 18. On line 17, the stretch from Parc des Expositions to Le Mesnil-Amelot, passing by Roissy - Charles de Gaulle airport, is still expected by the end of 2030.
Finally, the latest openings on the current schedule are slated for 2031, with the sections from Pont de Sèvres to Saint-Denis - Pleyel, then from Saint-Denis - Pleyel to Champigny Centre, on Line 15. All of these milestones remain provisional.
Official website
www.societedesgrandsprojets.fr
