RER B: New, more modern trains on the way — when is the MI20 set to enter service?

Published by Caroline de Sortiraparis · Photos by My de Sortiraparis · Updated on May 11, 2026 at 07:20 a.m.
It's a change that RER B users have been waiting for for several years. Soon, Europe’s second-busiest line will welcome the MI20. Hailed as roomier, faster and more modern, this next-generation RER B train is poised to transform the daily lives of many travelers. So, when will these new carriages be rolled out? Here’s what we know.

Parisian and Île-de-France public transport is undergoing another transformation. While four new metro lines (lines 15, 16, 17 and 18) are set to come online by 2031, other lines are being modernized. After the ligne 10, d’autres lignes du métro parisien will progressively replace their old rolling stock with the new train model, the MF19. By 2033, this new rolling stock will be in service on lines 3, 3bis, 7, 7bis, 8, 10, 12 and 13.

RER B: the MI20 arriving soon, newer trains on the way

On the RER side, changes are also on the way. In the near future, 146 new trains will eventually replace the MI 79 and MI 84 trains currently in operation. Named MI20, for "Matériel d'Interconnexion commandé en 2020", this upcoming RER B train is set to be markedly more modern.

Launched as “more capacious, more spacious, more comfortable,” these new trainsets will be able to carry 1,063 passengers, i.e. up to 35% more capacity, including 342 seated places (up to 22% more seats), as stated in a press release from Île-de-France Mobilités (IDFM).

RER B : bientôt de nouveaux trains plus modernes, quand est prévue la mise en circulation du MI20 ?RER B : bientôt de nouveaux trains plus modernes, quand est prévue la mise en circulation du MI20 ?RER B : bientôt de nouveaux trains plus modernes, quand est prévue la mise en circulation du MI20 ?RER B : bientôt de nouveaux trains plus modernes, quand est prévue la mise en circulation du MI20 ?
© ALSTOM SA 2026 - Samuel Dhote | MI20

The future RER B train will alternate single- and double-deck cars, and will thus offer several travel zones, including “wide low-floor zones” designed for people with reduced mobility, but also for travelers with luggage and strollers. The “two-level zones” — “providing seating, calm, and comfort for longer journeys” — are also announced.

Île-de-France Mobilités, which invested €2.5 billion in these new train sets, says the new trains will also be equipped with air conditioning, underfloor heating across the entire train, video surveillance “with real-time transmission of images,” USB-C ports, and numerous information screens, in order to offer RER B users “a higher level of comfort and security.” Incidentally, 44 video-surveillance cameras will be installed on the MI20, i.e., 50% more than today.

In detail, the MI20 will be 104 meters long, the same length as today’s rakes, and will be made up of seven short cars, instead of the four long cars used on current trains. Each train will also be wider—up to 20 cm wider than today’s trains.

So good news for the million travelers who ride the RER B every day, the second-busiest line in Europe, behind the RER A.

RER B : bientôt de nouveaux trains plus modernes, quand est prévue la mise en circulation du MI20 ?RER B : bientôt de nouveaux trains plus modernes, quand est prévue la mise en circulation du MI20 ?RER B : bientôt de nouveaux trains plus modernes, quand est prévue la mise en circulation du MI20 ?RER B : bientôt de nouveaux trains plus modernes, quand est prévue la mise en circulation du MI20 ?
© ALSTOM SA 2026 - Samuel Dhote | MI20

MI20 arrives on the RER B: when is its rollout planned?

With the MI20’s maiden test run completed on May 7 at Alstom’s Crespin site in Hauts-de-France, many are now asking when these new trains will enter service on the RER B.

« Thanks to the mobilization of actors at the urging of Valérie Pécresse, president of Île-de-France Mobilités, the delivery timetable could be tightened after the initial delays », IDFM said in a statement.

However, riders on the RER B will still have to wait, as the target for the first passenger service on the Île-de-France network is set for the end of 2028, as announced during the annual hearing before Île-de-France Mobilités.

Practical information

Official website
www.iledefrance-mobilites.fr

Comments
Refine your search
Refine your search
Refine your search
Refine your search