Partager

The Project 

In a first phase, VERGNET had installed 30 wind turbines on the windy plateau above MEKELE, in the north of Ethiopia, for the national electricity company (EEPCO).
In phases II and III of the project, 54 further turbines would be installed about 10 km to the northeast of the phase I site.
This new wind farm called for the creation of about 20 km of access roads and 54 platforms for the turbines.
The company wanted particular attention to be paid to the following points:

  • Optimizing soil displacement to limit transportation and sourcing needs, given the difficulties accessing this mountainous are,
  • Optimizing Ethiopian road regulations (the geometrical characteristics and dimensions of the roads), taking into account the specific features of the project (the very slow speed of vehicles and most of the traffic being expected in the construction phase, rather than afterwards).

Challenges

Client
Vergnet SA

Period
2011 – 2012

Key figures
54 wind turbine platforms
20 km of access roads

Challenge
A unique approach was taken to determine the structure of the future roads, taking into account the particularities of the project. These roads needed to bear heavy loads, but mainly over a short period (in the construction phase), making the usual parametric design methods unsuitable.
The loads were modeled using ALIZE software to define the pressure the roads would need to withstand. Based on these results, a catalogue of possible structures was produced for different ranges of soil characteristics.

The Assignment

Vergnet selected setec als (with the support of setec Terrasol for geotechnical aspects) to design the 20 km of access roads and the 54 associated platforms:

  • a critical analysis of the preliminary design and Ethiopian road regulations, and recommended derogations,
  • research into possible routes, taking into account physical and hydrographic constraints,
  • geometric design for the roads and platforms, and optimization of earthworks,
  • definition of the structure of the roads and platforms,
  • hydraulic scaling of the road and platform drainage systems.