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Removal of PN 46 at Sallanches (74)

Removal of PN 46 at Sallanches (74)

Geotechnical engineering

  • Project Owner : RFF
  • Project management : INGEROP
  • Mission : Assistance au Maître d’Oeuvre
  • Cost of the mission : 12 k€
  • Mission date : 2010 2011 design – 2013-2014 works


Level crossing 46 (PN 46) is located at the northern exit of the town of Sallanches, at the junction between the RD 1205 (formerly the RN 205) and the railway line linking La Roche sur Foron to Saint-Gervais les Bains.
It is one of the 400 NPs of concern identified by the Ministry of Public Works, RFF and SNCF at national level.
Under the chosen solution, the RD 1205 is diverted slightly and passes under the railway line via a hopper and a sloping underpass, joining the South roundabout.
The structure is 225 m long and around 15 m wide.
As the water table is shallow and the permeability of the ground is high (gravelly alluvium of the Arve), the structure requires the use of a temporary sheet-pile retaining structure, combined with a hydraulic plug at the bottom of the excavation. The final structure is an open concrete trench with a rail bridge in the middle.


GEOS carried out a G5 geotechnical expertise and assistance assignment in accordance with standard NF P 94-500.

These studies covered the following points in particular:

  • Definition of additional geotechnical and hydrogeological survey programmes;
  • Assisting the project management team in managing the G2 mission, during the project phase, carried out by an external geotechnical engineering office.





Posted on

27 July 2023