New delay in the delivery of the Grand Paris Express

It was expected for December 2025, but delays in conducting the tests forced the Société des grands projets (SGP), the project manager for most of the Grand Paris Express lines, to postpone its opening until summer 2026.

"I am very disappointed," reacted the president of the Ile-de-France region Valérie Pécresse to the announcement of this new delay on Thursday. "Line 15 South is extremely anticipated by the people of the Paris region, both the cities south of Paris but also to relieve congestion on the RER A and B by around 10 to 20%," she added.

Ms Pécresse called on the SGP to meet the new deadline because "six months of new delays does not mean we end up tomorrow with nine months, 12 months (...) or worse, postponed to 2027".

SGP President Jean-François Monteils, conceding that it was "bad news", insisted on "the extreme complexity of the Grand Paris Express, which is due first and foremost to its size", to justify this new delay.

Unexpected bugs

In total, lines 15, 16, 17 and 18 will form 200 km of an entirely new network of automatic metros by 2031, made up of 68 new stations spread throughout the Ile-de-France region.

This project, "the largest in Europe", according to Mr. Monteils, is estimated at 36,1 billion euros - compared to 22 billion in 2010.

The 15 South alone will be 33 km long and will cross 22 municipalities in an arc from the southwest to the southeast of the capital. Its cost remains unchanged despite the delay announced on Thursday, at 8 billion euros.

This is not the first time that this line has suffered a schedule shift. Initially expected for 2020, the inauguration was first postponed to 2023 before Edouard Philippe, Prime Minister in 2018, set the date for 2024. Covid and the interruption of construction sites then added a year to the schedule.

This time, it is the tests that are responsible for the delay. "We entered this test phase relatively recently, in September," instead of July, said Jean-François Monteils.

The teams then discovered "unexpected bugs, difficulties that we didn't fully anticipate," he added, without going into details.

He also highlighted the technical challenge of the project and its unprecedented nature, with service providers themselves "having added delays for their own internal security procedures", delaying the holding of the tests.

Expanded missions

The SGP, originally created for the design of the Grand Paris Express, saw its missions expanded in December 2023. It is now participating in the creation of the "RER Métropolitains" by being the project manager of the infrastructure necessary for the creation of these new services, which are set to develop throughout France.

"Ile-de-France - which is SGP's first customer - expects the project owner not to be distracted and for the company to keep its commitments on the fundamentals, that is to say to deliver the automatic metro lines on time and with the expected level of quality," Valérie Pécresse snapped.

Eventually, Line 15 is to be completed by sections to the east and west to form a circle around the capital. It will be 75 km long and will consist of 36 new stations, an infrastructure without equivalent in the world, according to the SGP. Its inauguration is expected for 2031.