The iconic and strategically important Alpine route — the Mont Blanc Tunnel — will be completely closed to traffic from 1 September 2025 at 17:00 until 12 December 2025 at 17:00. The closure has been scheduled to carry out essential ceiling renovation works.

What Will Be Renovated and Why?

As part of the second phase of renovation, following initial works completed in autumn 2024, two tunnel sections with a total length of 254 meters will undergo modernization.
The aim is to develop effective refurbishment practices that will allow future works on larger sections of the tunnel to be carried out more efficiently, minimizing long-term disruptions.

The Mont Blanc Tunnel, celebrating its 60th anniversary in 2025, is undergoing such an extensive modernization for the first time in its history.

Alternative Routes – How to Bypass the Tunnel?

Due to the full closure, drivers will need to use alternative routes:

• Fréjus Tunnel (Modane–Bardonecchia) – the most frequently chosen alternative, reliable and weather-independent, though it means a longer route and additional toll costs.
• Great St. Bernard Tunnel – located closer to the original route but requires passage through Switzerland, including border formalities.
• Alpine Passes – may be an option during the summer season, but in autumn and winter their accessibility is often limited.

Important Information for Tunnel Users

• Multi-pass subscriptions (10 or 20 passages) will be automatically extended by four months – this applies to all active cards on the day the closure begins.
• The renovation has been scheduled for the autumn period, when tourist traffic is lower, in order to minimize inconvenience for travelers and the local economy.

Summary

• Closure period: 1 September (17:00) – 12 December 2025 (17:00)
• Scope of works: ceiling renovation on two tunnel sections (total of 254 m)
• Objective: prepare for a full modernization of the entire structure in the coming years
• Detours: mainly via the Fréjus or Great St. Bernard tunnels
• User benefits: automatic extension of subscription card validity

The Mont Blanc Tunnel is one of the most critical transport corridors connecting France and Italy. Although the modernization will cause temporary transport disruptions, it is essential to ensure the safety and future efficiency of this key infrastructure.