SWISS Federal Railways (SBB) is preparing to start a four-year project to refurbish the 20km eastern bore of the Simplon Tunnel, which runs beneath the Swiss Alps, from Brig in Switzerland to Domodossola, Italy.

Work will take place over a period of six months every year until 2028. The initial phase of work will commence on February 3 and will continue until July 27. The project will focus on repairing parts of the tunnel vault and improving drainage. It is expected to cost SFr 55m ($US 58.2m).

Trains will continue to operate through the tunnel while the work takes place, although the frequency of some services will be limited, notably BLS car transport trains between Brig and Iselle which will operate every two hours instead of every 90 minutes. The majority of Brig - Domodossola Regioexpress trains will operate every two hours as scheduled. However, freight services will be affected due to “severe restrictions” on the four-metre corridor through the tunnel, SBB says.

The railway adds that the project will be coordinated with work taking place in other Swiss tunnels to ensure a minimum number of passenger and freight trains can operate through the Alps.

The Simplon Tunnel opened in 1906 and is used by around 250 trains every day.

Domodossola - Milan

SBB also confirmed that work to expand the four-metre corridor between Domodossola and Milan is continuing, which will result in further restrictions to services operating on the Simplon axis.

This includes the operation of only three Basle - Bern - Milan and Geneva - Brig - Milan EC trains instead of four in 2025, repeating the frequency offered in 2024. Four trains will operate at weekends.

The Domodossola - Milanline will be completely closed between June 8 and July 27, and August 31 - September 12 when buses will replace trains on EC services operating between Domodossola and Milan.

The February 2025 edition of IRJ will include an article looking at the resilience of railways in Alpine regions to extreme weather events and how infrastructure managers are attempting to maintain reliability.