Edited title Oct 10 2023 to reflect that authorities said it will be *several months -- sometime next Summer --before the rail line between Modane and Italy re-opens.
There was a landslide yesterday that has put a halt to trains between Chambery and Modane, which means that no trains can run between France and Italy on that route (nor are buses able to make a substitute drive because the road is shut down too).
This will be at least for the "next few weeks."
Even if you don't read French, you might take a look at the following article, which includes video that a bystander captured of the landslide (scroll down a bit in the article to get to the video. There are also a couple of tweets with more information / photos / diagrams). It's pretty easy to see why nothing can get by!
In addition, 18-wheelers are forbidden from using the Frejus Tunnel (I guess for caution regarding réverbérations) although I guess private vehicles can still use the tunnel (I don't know about big motorhomes).
A pain for anyone who was hoping to do Paris-Turin, Paris -Milan or Lyon-Turin or Lyon-Milan (or vice versa) these next few days. I am glad my husband came back from visiting his mother one week ago today !
Plus de train entre la France et l’Italie jusqu’à au moins mercredi après un éboulement en Savoie, le tunnel du Fréjus fermé aux poids lourds https://www.leparisien.fr/faits-divers/plus-de-train-entre-la-france-et-litalie-apres-un-eboulement-impressionnant-la43-partiellement-fermee-27-08-2023-FDLPLXJCQ5BVPKDSIXE3XIKPEU.php?xtor=AD-366 - via Le Parisien
8/30: I have edited the title to reflect, as JoLui pointed out, that today SNCF said it will be at least several weeks, rather than several days, before rail service is restored.