Opening delayed due to technical issues

The opening of the first section of the Grand Paris Express line 18, originally expected by the end of 2026, may now be delayed until 2027 due to "technical problems," according to three unnamed sources. One of the involved parties denied the claim, but the first section of the Grand Paris Express, a major public transport project, is reportedly "on hold."

Project scope and goals

The first section of line 18 is part of a broader network of four metro lines (15, 16, 17, and 18) being built across Île-de-France. The Grand Paris Express project plans to construct 200 kilometers of automated metro with 68 stations, aiming to connect all of Paris’s suburbs after 2031. This section will serve the Saclay plateau in southwest Paris, a hub for universities and research institutions.

Key stations and infrastructure

The first section of line 18 is scheduled to connect three stations: Polytechnique, Université Paris-Saclay, and Christ de Saclay. These stations are expected to be heavily used by residents, researchers, and professionals from the Saclay plateau. The section also includes the longest railway viaduct in France, spanning 6.7 kilometers.

Transfer of management and testing phase

After ten years of planning and construction, the Société des grands projets (SGP), the project owner, handed over the section to Île-de-France Mobilités (IDFM), the transport authority, and RATP GI, the infrastructure manager. Keolis, the future operator of the trains, was also involved in the handover. The next step was a two-month "white run" test, which would have tested the trains and their connections to the platforms without passengers.

Delays due to automation issues

The "white run" tests were not yet underway by Friday, as the technical and safety requirements for the test had not been fully met. RATP cited issues with the line’s automation system, managed by Alstom, and noted that additional tests were needed before the system could operate without passengers. IDFM expressed disappointment with the delay and pointed the blame at Alstom and the SGP.

Automation system under scrutiny

Mobilettre, a specialized transport magazine, reported that repeated failures in the automation systems related to train circulation were detected, with Alstom being held responsible. The magazine suggested that the SGP, the project owner, was at fault for setting "unrealistic schedules." When questioned, none of the involved parties provided specific details to AFP about the problems.

Alstom defends its work

Le Monde highlighted the complexity of the automation system designed by Alstom, which must manage both train movement and station equipment. The newspaper noted that this complexity was underestimated by the SGP. Alstom, which has been criticized, denied the claims, stating that it tested the automation system for over seven months with partners and that everything functions properly. The company added that no problems were reported and that the SGP would not have proceeded with the technical transfer if issues had existed.