Introducing Bio-engineering to the Road Network

                           Bio-engineering is the use of vegetation, either alone or in conjunction with civil engineering structures, to reduce instability and erosion on slopes. It should be a fundamental part of the design and construction of all roads in rural (and urban) hill areas, mainly because it provides one of the best ways to armour slopes against erosion. Because of the steep and dynamic slopes found in the Himalayas, most hill roads are engineered near to the margin of safety. Bio-engineering is an effective way of enhancing civil engineering structures to increase stability as far as possible. It is relatively low in cost uses local materials and skill, and provides livelihoods benefits through. economically useful products..

A study has shown that many roadside slopes in Himachal Pradesh (HP) suffer from a range of
instability and erosion problems, many of which are conducive to the use of low cost remedies such as bio-engineering. The Public Works Department (PWD) is examining alternatives to standardise civil engineering approaches and in particular is looking at the possibilities offered by bio-engineering, through the experience gathered in other parts of the Himalayas over the last few decades Between 1987 and 1990, the PWD’s Horticulture Wing was involved in soil conservation work to resolve shallow failures on road cut slopes. Though this programme has diminished with time, it still demonstrates the inherent capabilities that can be harnessed to good effect.

This paper describes the main types of slope instability found in Himachal Pradesh, their causes (natural and man made), treatment options to safeguard the road network and reduce long term maintenance costs; approaches to bio-engineering that are appropriate to the bio-physical and socioeconomic conditions found in the state; institutional mechanisms for these to be successful; capacity enhancement means and tools; and examples of success and failures from other parts of the world. It also documents early experience in the introduction of this type of approach through specific pilots of critical road sections that have been considered under the World Bank funded Himachal State Roads Project.

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