Highways

Highway Stabilization and Protection

Introductory Photo Essay VS_highway.pdf (vetiver.org)

Photo 1 Steep batter stabilized with vetiver – Ho Chi Minh Highway, Vietnam
Photo 2 Fill slope highway (Guatemala)
Photo 3. Not a highway, but a mountain top airfield in Myanmar stabilized with over 6 ha of planted vetiver. Plant material supplied by small rural nurseries (Thein Maw)
Photo 4 Excavated vetiver from a fill slope in Guatemala – Massive root system -better than steel! And a lot cheaper.
Photo 5 Vetiver is good for shallow fills of up to about 6 ft deep
Photo 6 Fill slope stabilization in Guatemala
Photo 7 Well planted vetiver on an urban freeway in Guatemala

Vetiver has made significant headway over the past 25 years for its application for highway stabilization where high cost infrastructure needs effective protection. Vetiver with its high tensile strength (av 75 MPa) and resulting shear strength improvement in soil has proven an effective means of stabilizing highway cut and fill slopes. There are now many companies in Latin America, Africa and Asia that are offering their vetiver expertise and services for bio-engineering applications of VGT.  The plant has long lasting positive impact on slope stabilization, and acting  as a pioneer plant allows native plants to establish on often “c” horizon soils.

Stabilization of a 2000 km highway in Vietnam – The vital role of the Vetiver System. Recently Paul Truong revisited sections of the Ho Chi Minh Highway, Vietnam, that have been stabilized with Vetiver System applications. He prepared this photo essay that shows the impact of VS over a fouteen year period. (2000 – 2014).  We are indebted to Van Tran and Tran Man (former and current Vetiver Network coordinators in Vietnam for some of the photos and the incredible work that was performed on this highway that follows the alignment of Vietnam’s famous Ho Chi Minh Trail.

The work and impact of these VS applications have to be considered, with the test of time, successful. There were some land slips (1 meter and 10 meter deep) that VS could not prevent, even so the overall results were excellent. Contrary to views of some critics the Vetiver System: (a) protected slopes of over 60%, (b) protected slopes against very high rainfall, (2000 mm per year) including extreme events under typhoon conditions, (c) provided a microclimate that allowed native plant species to naturally establish and eventually shade out the vetiver to the extent that in 2014 there is little evidence of vetiver in the earlier plantings – NOTE where native species did not establish vetiver continued to grow and protect the slopes, (d) resulted in a much reduced investment cost (estimated at 90% of hard engineering solutions), and minimum annual maintenance costs, and (e) proper engineering designs would assure even better results of VS application as a stand alone technology or in combination with hard engineering technology.

The experience on this highway confirms that VS could be applied widely for slope stabilization in developing countries where climate permits and where labor is relatively cheap.  It also confirms the need for good engineering design.

SOIL NAILING

On fragile slopes protecting high cost structures and subject to slippage engineered soil nailing backed by VS has proven a successful combination as shown in this presentation by Paul Truong
Vetiver System for Erosion and Sediment Control, and Stabilisation of Steep Slopes Power Point by Paul Truong (pdf MB 2.6) With special reference to Vietnam
Application of Vetiver Grass Technology in the Stabilisation of Road Infrastructure in the Wet Tropical Region of Australia Power Point by Paul Truong
The Vetiver System for Infrastructure Stabilization in Africa This is a modified power point showing how VS has been used for slope stabilization in Madagascar. It also shows how local communities have benefited from the production of vetiver plant material. The author, Roley Noffke, is a highly skilled and experienced road engineer and has worked widely with various Vetiver System applications. He can be contacted by email.
Fixing a major sand dune in Madagascar. Carol Knoll and Roley Nöffke’s illustrated article in July/August 2008 issue of Environmental Management. Hydromulch (Pty) Ltd has been involved in a major sand fixing, erosion control and slope stabilisation undertaking along newly constructed roads at the Rio Tinto/QMM Ilmenite Project at Fort Dauphin in Madagascar. Wind blown sand was a major issue and a decision was made to use barrier netting and Vetiver Grass hedgerows

MOUNTAIN ROAD PROTECTION COLOMBIA (including Vetiver)

Meclas Ecologicas Parrael Control dela Erosion y La Estabilidad de Taludes English Spanish