The problem of slope superficial instability at the Port d’Envalira mountain pass in Andorra has been solved with a geomat erosion control solution. Maccaferri’s MacMat® product provided the environment to enhance the growth of vegetation through the mat. After a year in the field, the slope has successfully revegetated.

Roadway Slope Erosion Control in the Port d’Envalira Mountain Pass
After a year, the mountain pass slope has fully revegetated. Photo by Maccaferri.

By Maccaferri – Port of Envalira is a mountain pass and the highest paved road in the Pyrenees at an elevation of 2,409 m above sea level. It is located in Andorra, between the towns of Soldeu and El Pas de la Casa. Together with the Envalira tunnel, this mountain pass is the only access point from Andorra to France.
Significant rain and snowfall generated slope erosion and superficial instability. Maccaferri’s geomat MacMat® R was chosen to secure the slope and prevent surface erosion from runoff.


MacMat® is a three-dimensional matrix of UV-stabilized, non-degradable synthetic fibers, heat bonded where they cross. It is used for long-term erosion protection applications and it immediately increases the soil’s resistance to erosion by providing an environment that enhances the growth of vegetation through the mat. The long-term performance of the vegetation is also enhanced, as the MacMat® R reinforces the root system of the vegetation, anchoring it in these fragile and vulnerable soils.
The reinforcement within MacMat® R gives the mat a far higher tensile strength and resistance to punching forces, which is essential when containing and preventing loose surficial materials and soils from slumping off the slope. This resistance enables it to be used extensively to provide the surface stabilization function within soil-nailed slopes.

Roadway Slope Erosion Control in the Port d’Envalira Mountain Pass
A green version of MacMat® geomats was used for a lower environmental impact and better aesthetics. Photo by Maccaferri.

For this project, Maccaferri provided two types of reinforced geomats:

  • 5,200 m² of MacMat® R 020, reinforced with geogrids
  • 900 m² of MacMat® R 8127 GN, reinforced with double-twisted steel woven mesh.

Both geomats are green in color for a lower environmental impact and better aesthetics.
The site photo at the top of this article shows how slope erosion was completely halted during the first year of the geomats in the field and that thick vegetation has settled in.
For more information Maccaferri’s erosion control materials, other geosynthetics, and engineering expertise, visit