The numbers speak for themselves: after compensating for 15 branches in 2023 and 5 in 2024, only two rail lines in Île-de-France will be eligible for reimbursements in 2026 for RER delays in 2025. This appears to be a superficial improvement that doesn't quite match the daily experiences of travelers on the RER B line and the RER C, especially on the northern and southern branches of Île-de-France.
Since 2021, Île-de-France Mobilités (IDFM) has implemented an compensation system for users of the most unreliable lines. The concept is straightforward: if a railway branch records a punctuality rate below 80% for at least three months in a year, the owners of the affected Navigo pass receive financial compensation. This initiative aims to offset the daily inconveniences faced by travelers dealing with a sometimes overcrowded and unpredictable network.
Looking ahead to 2025, based on data from the first eleven months published in the IDFM punctuality report, only two lines meet this quality standard: the Aulnay-sous-Bois - Mitry-Claye branch on the RER B North in Seine-Saint-Denis, which experienced five months below the critical threshold, and the Dourdan - La Norville line on the Line C in Essonne, which fell below 80% four times in eleven months. These two branches will therefore trigger automatic refunds for regular users in the spring of 2026.
At first glance, the statistics look promising. The A line, the backbone of the Île-de-France transit network, is projected to reach a punctuality rate close to 94.5% by the end of 2025—an improvement of one percentage point compared to 2024. In fact, it even surpasses the contractual targets set by the transport authority. A reassuring sign for the hundreds of thousands of commuters who rely on it daily, traveling between Val-de-Marne and Yvelines.
The RER B, long a plagued by delays and poor punctuality, is showing signs of progress with a punctuality rate of 88.8% across the entire line. While still just shy of the 89% minimum target set for 2025, this is a notable improvement. The upward trend is largely attributed to the reliability initiative launched in 2023, which is beginning to bear fruit despite ongoing fluctuations in service quality. Meanwhile, Line C also improved slightly, reaching 88.26%, though it still falls short of the expected standards.
On the other hand, Line E, already serving Haussmann-Saint-Lazare and extending to Nanterre by the end of 2024, ends the year with a punctuality rate of 90.22%, falling 2.5 points short of 2022. This decline is partly due to the adjustment period associated with this major extension into the Hauts-de-Seine. Meanwhile, RER D also experienced a 2-point drop without any structural reason, making it the line furthest from its punctuality targets. This situation is particularly concerning for commuters traveling north and south of Paris.
Associations are criticizing the system's overly binary approach to compensation. Essentially, a branch with 79% punctuality qualifies for reimbursement, while one with just 80.01%, such as the Vigneux - Corbeil route on Line D last November, does not.
If the rate doesn't hit 80% but reaches 79%, SNCF still considers it acceptable. However, this figure indicates that one in five trains is not on time. Is the 80% threshold truly reflective of a quality of service that meets the expectations of the millions of Île-de-France residents who rely on these lines daily for commuting?
Commuters on Line C, especially those on the non-reimbursed branches in Essonne, feel just as the strain as those affected along the Dourdan - La Norville route. Likewise, passengers on the RER E, who endured disruptions due to ongoing extension works, had hoped their patience would be acknowledged. As for users of the RER D, they will not receive any compensation, despite their line experiencing the most significant decline in punctuality across the network.
Despite some recent improvements on the RER B, the line continues to experience unpredictable performance. In November 2025, the Aulnay - Mitry-Claye segment hit a new low, with punctuality dropping to just 70%. Faced with this situation, IDFM has called on operators, SNCF Voyageurs and the RATP, to quickly turn things around. The transport authority blames these ongoing issues on "network reliability problems and operational difficulties."
One of the much-anticipated solutions is the renewal of rolling stock. The 146 new train sets ordered in 2020 to equip line B were originally scheduled to arrive in 2025. Unfortunately, the bad news is that their deployment has now been pushed back to 2030. This five-year delay is unlikely to ease commuters' daily routines in the near future.
On the Line C, the plans are even more ambitious but also further down the road. The Essonne branches, which are plagued by aging infrastructure and the complexity of a sprawling, "tentacled" line, will be transformed into a Line Y with a new terminus at Austerlitz. They will be equipped with modern, double-decker trains. The tender process is expected to be launched later this year, with delivery anticipated by 2032. In the meantime, how many ongoing delays will still need to be compensated for?
While major modernization projects are underway, commuters in Île-de-France will have to continue navigating a network that is gradually improving, albeit with ongoing vulnerabilities on certain lines. The 2026 reimbursements for delays incurred in 2025 will mainly benefit travelers on the Aulnay - Mitry-Claye and Dourdan - La Norville branches.
To verify if your line is eligible and to find out about the reimbursement process, you can visit the official Île-de-France Mobilités website. It outlines the criteria and steps to take when next spring.
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