Green walls reinforced with Fortrac® geogrids to
reduce the environmental impact on a stretch of
the CADAGUA motorway, Spain

The autonomic highway B-636 that unites the province of Bizkaia with that of Burgos crosses various locations and has a traffic volume of around 24,000 vehicles each day. With the aim of decongesting this highway and improving connections between the two provinces, the Cadagua motorway was constructed.
Its track crosses a zone that is of major scenic value and its axis, running parallel to the Cadagua river, cuts through the corridor bearing the same name.
For that reason, right from the project phase much attention was paid to studying the environmental impact of the work, the intention being to reduce this by means of green walls.

In total, five green walls were constructed, covering a surface area of 5,140 m2 and with a maximum height of 15.5 m. The inclination of the walls is 65° and a metallic grid was used to shape the anterior face of the wall.
Fortrac® geogrids with a resistance between 35 and 200 kN/m were used to construct these walls. An anti-erosion geogrid was also placed in the anterior face of the walls to prevent the vegetative soil being washed away.
The entire material employed to fill in the walls was obtained from blasting work carried out along the stretch of this highway. This material was processed in a crushing plant used for the project until material with a maximum granulometry of 16 cm in diameter was obtained. This had a beneficial effect on the soil, while reducing the costs incurred by the construction firm.
To achieve a vegetative cover for these walls, hydro-sowing was conducted using various native species which, benefiting from the climatic conditions of the zone, gave rise to walls that blended perfectly into the surrounding area.
Constructed: August 2005 to March 2008
Proprietor: DIPUTACION DE BIZKAIA
Works management: INTERBIAK, Spain
Project and technical assistance: SAITEC., Spain
Construction firm: UTE NOCEDAL, Spain
Product: Fortrac®-geogrids