Probable causes and corrective measures of landslides on Aizwal-Lunglei Road (NH054), Mizoram

Landslide is the main cause of massive damage in tectonically active hilly terrain of the Himalayan region, including the state of Mizoram. It may be disastrous, causing destruction to life and property. This leads to large-scale landscape transformations. Aizwal-Lunglei (NH-54) road is an important highway connecting the people of south Mizoram to other parts of the country. This highway got damaged due to landslide at chainage 173.5 km near Hnathial town of about 100 m long. Due to this, one lane of the two-lane highway washed away, resulting in the hindrance of smooth traffic flow. In order to restore the road, systematic geological and geotechnical studies were carried out to identify the causative factors responsible for the landslide. The factor of safety of the existing slope was observed to be critical and close to unity. Remedial measures were proposed to the uphill slopes like construction of new culverts, drains, shotcreting on the exposed rocks, etc. Similarly, construction of gabion and reinforced retaining walls were proposed on the downhill slope. Stability analysis was again carried out after physical remedial measures and observed to be safe.