Making Northeast highways truly disaster-resilient

The central government’s decision to prioritise slope stabilisation before beginning road construction in hilly terrain to ensure long-term safety and durability has great relevance for the northeastern region. As the region is highly susceptible to devastating landslides, strict implementation of this policy decision is critical to ensure that highways in its hills function as genuine all-weather corridors. An expert committee constituted by the Ministry of Road Transport and Highways (MoRTH) on ‘Cost-effective long-term remedial measures of landslide-prone areas in hilly regions’ underscored the need to focus on sustainable solutions that mitigate the risk of landslides without imposing excessive financial burdens. The MoRTH urged all stakeholders involved in highway construction in hilly regions, through an office memorandum, to use the report of the expert committee as reference/guidance while finalising investigations and mitigation measures. Establishment of a strong institutional oversight mechanism is critical to guarantee that construction agencies adhere to the slope stabilisation measures recommended by field engineers based on different matrices of investigation and mitigation of landslides recommended by the Expert Committee. The Office Memorandum states that expansion of National Highways in hill roads having mountainous/steep terrain involving a lot of hill cutting has resulted in landslides and destabilisation of slopes. This harsh reality not only speaks volumes about the uncertainty that continues to grip the movement of passengers and goods in the region, especially during the monsoon period, but also about the gaps in mitigation measures that persist. The Expert Committee points out that while there are several protection measures available for the stability of slopes, such as natural vegetation, rockfall barriers, surface treatments and structural treatments, and various types of topographic and geophysical investigations are also available to characterise the slope and decide the treatment measures, there is a gap in identifying the type of investigation needed for a particular type of slope and, subsequently, the selection of the type of mitigation needed. The committee says that because of this gap, there is inconsistency in the field investigations done and the mitigation measures used for similar slopes, which sometimes leads to expensive structural solutions that aren’t properly justified. The government informed the Lok Sabha in March that based upon the learning of failures of hill slopes during construction, environmental impact assessment reports, etc., various initiatives for developing disaster-resilient NHs infrastructure have been taken. These include consultants, including slope studies and stabilisation as part of detailed project report preparation; geological and geotechnical investigations are to be carried out covering both within and beyond the right of way (ROW) to prevent damage to property and infrastructure; due emphasis is to be given for the construction of catchwater drains, side drains with catch pits, cut-off drains, cross drainage, etc.; implementation of standardised parameters for investigating hill slope stability and selecting cost-effective long-term stabilisation measures for landslide-prone areas in hilly regions; and refining of hill construction methodology which mandates initial construction only for hill cutting and slope protection and subsequent highway construction only post stabilised cutting formation and protection work. The Expert Committee’s recommendation for different matrices of investigation and mitigation of landslides will provide the templates for standardisation, but a dynamic approach will be essential to keep updating the standards and strategies based on dynamic geophysical changes and climate-induced changes established through new scientific investigations. The central government providing support to IIT Roorkee for the development of guidelines for the assessment of hillslope instability instrumentation & real-time monitoring is a crucial step, and speeding up the work of developing these guidelines will be especially important for the Northeast region, as it will strengthen the safety and reliability of the hill highways in the region. While advancement of scientific investigations and research remain vital for resilient infrastructure in fragile hills of the region, monitoring and inspection of the infrastructure created for regular and timely maintenance can play the most crucial role in keeping the highways open round the year. Besides, the region must also build institutional and technical capacity needed to meet project timelines so that mitigation measures are also implemented on time and risks are not allowed to persist and make the highway stretches prone to catastrophic landslides. Highways in the northeastern hills are the lifelines for the communities living in areas connected by them. Therefore, frequent and recurrent disruption of vehicular movement along these routes due to landslides has serious social and economic consequences. The stabilisation of slopes and the implementation of mitigation measures to make the highways in the Northeast hills resilient to landslide risks are not only engineering priorities but also necessities to keep these hill routes open year-round, ensuring uninterrupted supplies and essential deliveries, as well as providing communities with consistent access to healthcare and education. Building disaster-resilient highways must remain the central focus of all connectivity projects in the region.