• Client : Reunion Regional Council
  • Period : From 2001 to 2004
  • Country : Ile de la Réunion,
  • Market : Bridges, Infrastructure Transport
  • Domain / Subdomain : Conceptual & Basic design (FEED), Engineering Procurement Construction Contracting Engineering Procurement Construction Management EXECUTION FEASIBILITY Feasibility Studies & Basic Design

Tractebel Engineering was the EPCM contractor for the construction of the Ravine Fontaine viaduct in Réunion.

The viaduct crosses a deep, steep-sided ravine, forming part of the Route des Tamarins dual-carriageway highway. The concrete arch bridge spans 200 metres.

The project is sited in complex geological conditions:

  • Basaltic formations formed by lava flows from the Piton des Neiges volcano
  • Alternation of strata of widely varying stiffness (basalt and scoriaceous rock)
  • Ravine walls constantly changing (scree, undermining)

The foundations are formed by concrete blocks thrusting against beds of consolidated basalt. They are built into the abutment to avoid changing, unstable zones of the ravine. The thrust blocks required meticulous excavation.

Tractebel Engineering delivered the following services:

  • Full supervision of the following aspects for the foundations:
    • Preliminary design
    • Tender design
    • Assistance in the contract award process
    • Construction supervision
  • Geological and geotechnical studies
  • Definition and follow-up of additional investigations
  • Design of foundations and earthworks
  • Foundation construction
  • Cost and construction time estimate

The most serious challenge was posed by the foundation displacements, which could not exceed a distance of 2 cm. Under very complex geotechnical conditions, Tractebel Engineering formulated solutions to strengthen the soil, and to adapt the project to new constraints that arose during the geotechnical investigations.

Tractebel Engineering’s part in the conception and supervision of the Ravine Fontaine Viaduct didn’t go unnoticed. We were awarded the ‘2010 ECCS Award for Steel Bridges (for outstanding steel and composite bridges)’.