Paris and Ile-de-France will open their first new metro line in 30 years at the beginning of December, line 18, eagerly awaited by thousands of students and researchers based on the Saclay plateau (Essonne).
On the other hand, the commissioning of future line 15, an arc of 16 stations irrigating the south and east of Paris and serving in particular the Gustave-Roussy hospital in Villejuif (Val-de-Marne), will be postponed by six months, announced Thursday, June 25, the Société des Grands Projets (SGP), project owner of the titanic project to build a large urban metro loop around Paris serving all Ile-de-France.
The commissioning of line 18 linking Massy-Palaiseau to Paris-Saclay University, in Essonne, is set for “the first week of December 2026”, indicated the SGP. That of line 15-South will be postponed to “fall 2027”, instead of April 2027, added the project owner, following a supervisory board meeting.
The first section of line 18 has only four stations (Massy-Palaiseau, Polytechnique, Université Paris-Saclay and Christ de Saclay), but it is particularly awaited by the approximately 70,000 students, teachers, researchers and employees working in laboratories, companies or major schools established on the Saclay plateau. The announced date will not allow this automatic metro, which will be operated by Keolis, a subsidiary of SNCF, to be ready in time for the start of the university year, but it respects the schedule which provided for entry into service “in the fall”.
The “transfer to technical management”, that is to say the moment when the SGP will officially transmit the keys of the new line to Ile-de-France Mobilités (IDFM), the transport organizing authority in Ile-de-France, is scheduled for “September 30”. It will be followed by a two-month “dry run” carried out by Keolis, but also by RATP Infrastructures, responsible for maintaining this new network.
The opening of the second section of this line 18 is planned for the end of 2027, which will reach Orly airport.
“Capitalize on experience”
For line 15-Sud, an arc of 33 kilometers to the south and east of Paris, which has 16 stations between Pont de Sèvres (Hauts-de-Seine) and Noisy-Champs (Seine-Saint-Denis), the “adjustment of the commissioning deadline is due to difficulties intrinsically linked to the scale of the project,” explained the president of the SGP board of directors, Jean-François Monteils. “We are not satisfied with announcing this adjustment, we would prefer not to have to do it, but transparency is important,” declared Jean-François Monteils.
This new postponement comes after an initial slip-up two years ago. According to the SGP, it is due to a three-month delay during the change of integrator design office, in 2024, and another three-month delay linked to an “inertia effect” between the 835 companies involved in the project, in particular during the pause of equipment on the tracks to begin the tests.
“We are confident, because we will capitalize on the experience of the commissioning of line 18, (…) and we have made considerable progress on the number of equipment on 15-Sud connected to the brain of the line,” added Jean-François Monteils.
Each station has some 700 pieces of equipment (cameras, elevators, electronic automatic pilot systems, signals, etc.) connected to the centralized control station. “In 2024, 3% of the equipment on line 15-South was connected, and today, we are almost 100%,” underlined Jean-François Monteils, specifying that rolling stock tests (Alstom) have started in the system qualification zone.
The SGP supervisory board also unanimously elected the mayor of Massy-Palaiseau, Nicolas Samsoen, as president on Thursday, replacing the mayor of Saint-Ouen-sur-Seine (Seine-Saint-Denis), Karim Bouamrane. Nicolas Samsoen, a graduate of the Ecole Normale Supérieure and the Ecole des Ponts et Chaussées, notably headed the public development establishment of Mantois Seine Aval, then a division of the transport operator Transdev.
