BIO-ENGINEERING FOR SUSTAINABLE ROAD MAINTENANCE (Paper 683)

Roads in Nepal run through mountains and are crossed by major rivers and their tributaries. Different types of instabilities are caused in mountain road slopes depending upon the type of material and the environment. The experience of hill road construction in Nepal shows that the sustainability of road in the mountains depends on proper alignment selection, slope drainage and slope management. Spoil management and the use of slope stabilization measures are other important factors to be considered. Cut slopes on the hill side need to be steep to reduce earthworks and fill slope angle on the valley sides must be safe to sustain the saturated fill materials during monsoon. Road construction causes widespread damage to vegetation and other adverse environmental consequences. The only cost effective way to protect slopes against erosion and shallow landslides is through the use of vegetation. 
Bio-engineering offers comprehensive solutions to reduce slope instability problems when combined with appropriate civil engineering measures. A form of bio-engineering is adapted for the unique environmental, economic and institutional conditions in the road sector of Nepal. This concept emphasizes on preventive measures and begins from the planning stage of the road promoting sustainable maintenance. Bio-engineering work by fulfilling the engineering functions required for the protection and stabilisation of slopes. Bio-engineering techniques developed in Nepal are simple and labour intensive. This provides employment to the local communities and they can perform income generation activities through the bio-engineering process.