Closure of the Mont Blanc Tunnel from September 2025

Please note that the Mont Blanc Tunnel will be completely closed to traffic from Monday, 1 September 2025 at 5 p.m. until Friday, 12 December 2025 at 5 p.m., in order to allow for routine maintenance and renovation of the vault. The closure will last approximately fifteen weeks, as announced by the Mont Blanc Tunnel EIG. The works will affect two sections of the vault totalling 254 metres, located about eight kilometres from the French entrance. The continuous closure is necessary due to the complexity of the works, as daily removal and reinstallation will not be feasible. Traffic will be mainly diverted through the Frejus Tunnel, which will accommodate most industrial vehicles, while cars will be redirected between Frejus, Gran San Bernardo, and the Alpine passes. However, certain restrictions will complicate the alternative routes: the Colle del Piccolo San Bernardo will close on 22 September for works on the French side, and the Gran San Bernardo Tunnel will face nine night-time closures between 25 August and 21 October due to works on the Swiss cantonal road. A detailed map of the alternative routes is already available on the tunnel’s website and on the Tmb Mobility app. The operator has also introduced a measure to assist regular users: all 10- or 20-trip passes valid on 1 September 2025 will be automatically extended by four months, with no action required by customers.