RER B works: dates, times and alternatives from September to December 2026 Last updated: September 1, 2026
As part of modernization works, the RER B line will be undergoing works in 2026 on several dates and sections. These closures have a direct impact on your journeys: find the schedule and our advice in this article.
Key dates
As part of the RER line works 
, service interruptions are scheduled on these routes:
🚫 All day:
- Gare du Nord <> Denfert-Rochereau
- Aulnay-sous-Bois <> Mitry-Claye
🚫 In the evening from 10:45 p.m.:
- Aéroport Charles de Gaulle 2-TGV / Mitry-Claye <> Châtelet – Les Halles
- Aéroport Charles de Gaulle 2-TGV / Mitry-Claye <> Denfert-Rochereau
- Aulnay-sous-Bois <> Aéroport Charles de Gaulle 2-TGV / Mitry-Claye
Alternative routes
Click on the diagrams to see all the alternatives based on your departure and arrival points🚫 Aéroport Charles de Gaulle 2-TGV / Mitry-Claye ↔ Châtelet – Les Halles
Replacement buses will be provided and the regular bus line will be reinforced. You can use the recommended alternative routes shown in the diagram below, allowing for a longer journey time.
🚫 Aéroport Charles de Gaulle 2-TGV / Mitry-Claye ↔ Denfert-Rochereau
Replacement buses will be provided to make your journeys easier and the bus line 
will be reinforced. You can use the recommended alternative routes shown in the diagram below, allowing for a longer journey time.
🚫 Gare du Nord ↔ Denfert-Rochereau
The bus line and the metro line 
will be reinforced. Trains to Aéroport Charles de Gaulle 2-TGV/Mitry-Claye will depart from surface tracks 31 to 33 at Gare du Nord.
🚫 Aulnay-sous-Bois <> Mitry-Claye
A replacement all-stops shuttle will run between Aulnay-sous-Bois and Mitry-Claye, with a frequency of every 5 to 15 minutes depending on the time slot.
🚫 Aulnay-sous-Bois <> Aéroport Charles de Gaulle 2-TGV / Mitry-Claye
The replacement bus B4 will operate during this period.
Adapt your journeys with the Bonjour RATP app
🔎 Find the best route
Start a route search: the results anticipate disruptions to help you avoid construction areas. Then customize according to your needs: schedules, modes of transport, lines or stations to avoid…
🚦 Check live traffic information
Access real-time traffic status via the app's Traffic tab. You can enable personalized alerts to be notified when your lines are affected.
📹 Demo: follow traffic information with the app
The Bonjour RATP app, your ally for anticipating disruptions and
finding the best routes during construction work
