Remediation and widening of the Sierre tunnel

Remediation and widening of the Sierre tunnel


Chemins de fer fédéraux suisses CFF


  • Design : 2009 - 2012
  • Works : 2012 - 2015


In a partnership of MPAIC-BG-PRA-SRP

Total costs

62.1 mio EUR

Project description 

The project involved the creation of new two lane tunnel bore south of the existing tunnel bore. This required that the following construction works be undertaken:

  • a 250m long section of open cut-and-cover trench, supported using retaining walls, with a new rail slab;
  • a 60m long cut-and-cover piled-slab section in the side of a hill;
  • a 250m long section of tunnel in soft ground, with limited soil cover and as close as 6m to the existing tunnel (in use) – excavated using forepoling;
  • a 60m length of cut-and-cover trench within the Glarey neighbourhood – piled slab structure, excavated top-down with a reinforced concrete frame;
  • a 150m long section of deep open trench with retaining walls (from 8-10m deep), with a new rail slab.

The project was developed in coordination with Techfer CFF and with the commune of Sierre for the urban development.

The works took place while the existing tunnel remained operational, which was a particular challenge during the existing tunnel reinforcement works.

Services provided

  • Planning application;
  • Detailed design;
  • Tender process;
  • Construction design;
  • Resident engineer;
  • Commissioning.

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