Contractors building an embankment to support a new junction between the A2 and A282 arterial roads adjacent to the M2 Motorway in Kent turned to geotechnical specialists Maccaferri, for their environmentally friendly reinforced soil system, Green Terramesh.
16/07/2007
The junction was to be widened from 3 to 4 lanes to improve traffic flow, but because of the environmentally sensitive nature of the countryside close to the carriageways, the usual 1:2 slope of conventional embankments could not be used. The expanded footprint of the road would have destroyed mature hedgerows which formed the habitat of several nationally scarce and vulnerable species
Main contractor, Costain Ltd, needed a solution that provided a steepened slope, thereby reducing the land take and saving the crucial hedgerow. After consulting Maccaferri, they chose Green Terramesh, incorporating an innovative formwork system that creates a “green” faced reinforced earth retaining wall in conjunction with polyester geogrids and compacted back fill.
The Green Terramesh strengthened earthwork created a 9.3m high embankment with a maximum angle of 70 degrees. Green Terramesh units include a factory-fitted welded wire ‘lost shutter’ formwork with a pre-set face angle. No external formwork is needed so reducing construction time significantly and providing a crisper face, when compared with traditional geogrid wrapped-face structures built with external and removable, formwork.
Bio-degradable vegetation matting, also factory-fitted to the face of the unit forms a 300mm wide reservoir for top-soil, creating a nutrient-rich environment which promotes rapid vegetation cover, effectively hiding the units, resulting in a natural, green aspect to the slope.
The Green Terramesh units were installed in conjunction with Maccaferri’s Enkagrid PRO, to provide primary geogrid reinforcement. The system is designed to use compacted site-won materials as the structural back-fill, further enhancing the system’s green credentials.
Work began on the structure in December 2006 and was completed in January 2007.
Maccaferri Ltd is the UK subsidiary of the worldwide Maccaferri Industrial Group which has its headquarters in Bologna, Italy and manufacturing facilities in over 20 countries, worldwide.
Traditionally known for the production of wire mesh “gabions” – used for erosion protection and slope reinforcement in rail, road and waterway applications, Maccaferri has expanded significantly over recent years and now operates over a wide range of geotechnical and civil engineering disciplines.
