WEAK SOILS IN HILLY AREAS MAY COLLAPSE DUE TO HEAVY RAINS AND THE INCREASE IN THE INTENSITY OF THE RAIN FALL WHERE AN ARTIFICIAL MECHANISM OF SOIL EROSION IS TOO NECESSARY TO CONTROL THE ROAD PROFILES.

The National Highway authority of India has been asked by the Honourable High court of Himachal Pradesh to report the unscientific construction of Highways and tunnels provided for shortcut approach to access the level on hill concave or open curve .As for as the road construction in hilly areas are concerned the access to move forward on destination is proposed it is not possible to leave the survey and trace cut where different type of soil and earth is required to be maintained by cutting or filling in the line of existing road .If the earth is very soft on the alignment of the proposed road that is also required to be protected by way of the breast walls and the Retaining walls however in such cases it is necessary to increase slope of the hill cutting profiles as per the guide lines of the codes and specifications given by the IRC recommendations issued for the provision made and described for the designated alignment.In the hilly areas it is not possible to avoid the curves in construction of the road works however at the same time it is necessary to follow speed limit and radius of curves passing through the density populated areas.The minimum length of transition provided for hill curves under IRC standard is fifteen metres for design speed up to 40 km per hour and twenty metres for fifty km per hour. For safety of road it is necessary to protect the road side drainage and the cross drainage from where water may be collected from the system of drainage channel and accordingly disposed .In hilly areas it is not possible to access road construction without Retaining walls and the breast walls for which necessary design fundamentals are required to be followed by the construction agencies failing which it is not possible to protect the road profiles.In case where the stata of the soil is very weak there are chances in heavy rains that it may collapse from the top of the hill for which the area above the road must be protected by way of the plantation and other methods of erosion control by construction of horizontal benches up to the top profile of the slopes for the erosion control as such weak soil may come down and collapse in the areas where no artificial mechanism developed for the erosion control which may slide down in any shape and size of the portion expected to come down during the heavy rains and could not be controlled without the artificial mechanism of the such hills for which the preliminary investigation is of utmost importance and should be undertaken by the experienced Engineers and may be done by walking on the probable routes required to verify the conditions of the soil erosion .As for as the Roads in plain is concerned there is no danger of slips and hill collapse down however roads in embankment may wash in floods due to weak spots of the cross drainage system for service and regions of high rainfall intensities, where it is necessary to protect the cross drainage works smoothly.