The National Highways Authority of India (NHAI) has launched a large-scale geotechnical investigation across the entire NH-66 expansion project in Kerala following the recent collapse of a reinforced soil (RS) wall at Mylakkadu in Kollam.
In order to address concerns over structural integrity, the NHAI has employed 18 geotechnical agencies to perform rigorous soil sampling and testing at a total of 378 RS wall locations across 18 different highway projects in Kerala. This comprehensive audit will cover sites that are already constructed, currently in progress, and those yet to begin.
The appointed agencies are required to deploy multiple drilling rigs within the next 7 to 10 days, with the goal of completing tests at 100 locations within the first month and finalising the entire assessment within a three-month time frame, aiming to quickly ascertain the safety and stability of all reinforced soil structures along the corridor.
The collapse of the RS wall at Mylakkadu, which was part of the approach structure to a vehicular underpass on the Kollam–Kadambattukonam NH-66 project, is linked to a fundamental geotechnical problem. Preliminary assessments of the NHAI indicate the collapse of the 9.4-metre-high wall was due to a deep-seated shear or bearing capacity failure. Essentially, the soil beneath the foundation was critically weak and unable to support the heavy load imposed by the RS wall and the massive earth fill behind it.
Expert team
Following the failure at Mylakkadu, a high-level expert committee was sent to the site on December 6 to investigate the causes and recommend corrective measures. This team included Jimmy Thomas (IIT-Kanpur) and T.K. Sudheesh (IIT-Palakkad) and according to the NHAI, the findings of a previous expert committee, constituted after the Kooriyad embankment collapse in Malappuram, are already being acted upon.
In light of a separate incident in November (the falling of girders on the Aroor-Thuravoor elevated road project) the NHAI had already engaged RITES to conduct a targeted safety audit on that specific stretch. This safety audit is now being expanded to cover all other NH-66 projects, aiming to identify and rectify any potential safety concerns across the entire corridor.
The NHAI has affirmed that various field and lab reports generated after proper investigations will serve as the basis for re-checking the design and construction of every single RS wall. Remedial measures, including the potential dismantling and complete reconstruction of walls, will be mandated wherever necessary. The NHAI has stated that no RS wall will be accepted until this stringent review process is complete and quality standards are fully confirmed.
Published – December 11, 2025 06:19 pm IST
