The Project 

This A89-A6 link  will connect the current end of the A89 motorway at La Tour de Salvagny with the A6 motorway at Limonest in the Rhône department. This “missing link” between two major national routes will help ease congestion around Lyon.
Numerous engineering structures are involved:

  • the 210 m Semanet Viaduct with a dual deck and composite weathering steel girders,
  • 2 box girder structures on the A6 to create while in operation,
  • 4 new underpasses,
  • 1 underpass to widen,
  • 7 structures to modify (demolition of dry stone, modification of retaining structures and heightening),
  • 1 structure in coated girders on the A6 to create while in operation.

Several existing structures to be demolished.
A range of hydraulic structures, acoustic barriers, retaining walls, etc.


Project owner
APRR (Autoroutes-Paris-Rhin-Rhône)

2014 – 2018

Hervé Vadon

For this project, setec als has designed and supervised the construction of the Semanet Viaduct. This structure is composed of two composite decks in weathering steel resting on rigid-frame(?) piers anchored in 1400mm – diameter piles.

The specific geometry of the piers required advanced modeling and calculations, using setec tpi’s Pythagore software.

The Assignment

APRR commissioned setec to manage the design (preliminary and detailed) and construction work on this motorway section, as well as contractor assistance, including:

  • design for the layout of slip roads and an interchange,
  • structures,
  • drainage,
  • environmental studies,
  • hydraulics,
  • landscaping and architectural planning,
  • topographic survey,
  • geotechnics,
  • regulatory documents: state approval,  requests regarding the protection of water, protected species, land/forest clearing, public consultation, etc.