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Tuesday, June 9, 2015

VETIVER SYSTEM. RAILWAYS, and CHINESE CONSTRUCTION COMPANIES

Side slope of road cutting (height: 15-20 m)
2 years after vetiver grass planting
The Vetiver System has been successfully applied to a number of important railroads in China since 2000. A paper presented at ICV6: "Application of Vetiver Grass for Protection of Railway Side Slopes"  by Xinmin Jiang, Tian Guan, Deyou Hu and Lehong Tang (email: tanglh@jstp.com) provides good evidence of the success and longevity of the applications over time by the Shanghai Railway Bureau.
The vetiver slope remains completely protected
 after a rainstorm of 114mm. Lower half of picture
used conventional system and native grasses.
VS was able to stabilize batters up to 20 meters high and protect them against extreme typhoon rainfall events.

Although the China Railway Corporation recognizes vetiver in its guidelines it has laid down provisions that VS, like other plants used, must be applied as part of masonary and geofabrics design. This defeats the $10-$15 savings per square meter that VS has over conventional "hard" technologies.  Is this another "too good, too cheap" intervention to favor hard technology?   Chinese highway construction companies have successfully used VS in China and Africa (see Alain Ndona's Congo paper).
Conventional herringbone construction
with failed vegetation - fairly
typical of native grasses.
China is embarking on some major highway and railway construction projects in Africa, Asia and Latin America.  Most of the alignments are located where vetiver grass will grow very well, and where there are professional engineers such as Alain Ndona who have the experience and capability to see the technology is properly applied.  We would urge that decision makers/potential contractors/communities that are associated with these Chinese funded projects press for the inclusion of VS - "a green and proven solution" that will assure that the investment will stay in good order at minimum maintenance for a long time!  See Van Tran's paper: "Vetiver System for Infrastructure Protection in Vietnam: A Review after Fifteen Years of Application on the Ho Chi Minh Highway (2000- 2014)"
Dick Grimshaw

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