Marti trains help SBB tunnels’ renovation

13 October 2020

Infrastructure provider Marti has created new tracked modules for Swiss Federal Railways (SBB) that will facilitate urgently-needed repairs to three tunnels on CFF Line 224/Lot 3 Neuchatel-La Chaux de Fonds.

Two construction trains have been designed to maximise production rates and give better safety to workers and operatives. They are now in use on the rehabilitation of SBB tunnels Mont Sagne (1,354m), Tunnel Mont Sagne (3,259m) and Tunnel Combe Convers (254m) between Neuchâtel and La Chaux-de-Fonds.

Geology along the line comprises Jura rocky chain – the result of the folding of Mesozoic marl-limestone strata. The limestone sections are fractured, karstic and are potential aquifers.

In the first construction phase which will last until the end of February 2021, the work will comprise systematic cutting and mechanical removal to eliminate sub-profile areas, as well as anchoring work to secure brick vaults. Phase 2 will see the removal and replacement of the vaults with shotcrete and is expected be completed at the end of 2021. Other work will include tunnel widening near portals using pipe umbrellas and the excavation and support of additional niches.

The works – which will be undertaken during evening line closures – are projected to consume 20,000t of shotcrete, 113t of steel lattice girders and over 10,000m2 to be waterproofed.

Marti NE-CF Consortium – comprising Marti Tunnel and Marti Travaux Spéciaux – is undertaking the work which is expected to be completed by April 2022.