RER A works: dates, times and alternatives between September and October 2026 Last updated: September 1, 2026
Between September and October 2026, the RER A line will be closed on certain dates and on several sections. These closures have a direct impact on your travel: find the schedule and our advice in this article.
Key dates
Service disruptions are scheduled on the RER line 
to modernize infrastructure, strengthen safety, and improve passenger comfort.
Replacement transport services will be provided during these periods.
🚫 Disruption Nanterre–Préfecture <> Cergy–Le Haut/Poissy
From September 14 to October 9 inclusive, Monday to Friday from 10:00 p.m.
Alternative route:
- Nanterre–Université <> Cergy–Le Haut (all stops) +60 min
- Nanterre–Université <> Cergy–Le Haut (semi-fast) +45 min
- Nanterre–Université <> Poissy (all stops) +30 min
- Achères–Grand Cormier <> Sartrouville / Maisons-Laffitte / Poissy (on-demand transport) +30 min
🚫 Disruption Maisons-Laffitte <> Cergy-Le Haut
From October 12 to 30 inclusive, Monday to Friday from 9:50 p.m.
ℹ️ From October 27 to 31, the first departure from Cergy–Le Haut from Tuesday to Saturday will start at Maisons-Laffitte. A bus service will run from Cergy-Le Haut to Maisons-Laffitte.
Alternative route:
- Sartrouville <> Cergy-Le Haut (all stops) +45 min
- Sartrouville <> Cergy-Le Haut (semi-fast) +25 min
🚫 Disruption La Varenne-Chennevières <> Boissy-Saint-Léger
From October 16 to 29 inclusive, from 9:45 p.m.
Alternative route:
- La Varenne-Chennevières <> Boissy-Saint-Léger (all stops) +20 min
Adapt your journeys with the Bonjour RATP app
🔎 Find the best route
Start a route search: the results anticipate disruptions to help you avoid work zones. Then customize according to your needs: schedules, transport modes, 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 works
