When on the afternoon of 5th December, a veterinary doctor R. When Resmi set out, she had no idea that her routine journey would turn into a terrifying race for survival. While walking on the familiar service road under the under-construction National Highway 66 (NH 66) at Mayilakkadu near Kottiyam in Kollam, he got a sharp, unexpected shock.
Her car turned sharply, and before she could react, the right side of the vehicle went up. His immediate thought was an earthquake.
Then a stampede broke out. The driver of an autorickshaw ahead of him started shouting and urging him to run away. She abandoned her car and ran for her life. Looking back he saw a scene of complete chaos.
surface opens up
The reinforced soil (RS) wall of the embankment was breaking, spilling soil and debris onto the road. An elderly woman who had come out of the car behind Resmi was paralyzed with fear as the road surface unraveled faster than she could handle. He was saved by the quick action of the residents.
A school bus was also stuck between the vehicles. As soon as the road opened, the bus driver and a staff member took the children out. They were immediately joined by local residents and together, they were seen carrying small children and running to safety.
“The wall was on the right and the paddy field was on the left,” says Resmi.
scary situation
She says, “We had no option but to run fast on the cracked, unstable surface. As we ran, the road bulged badly, electric poles started bending and water started flowing from fresh cracks. It was a very scary situation.”
Vehicles were seen stranded on the service road after a reinforced earth wall collapsed on the under-construction National Highway 66 at Mayilakkadu near Kottiyam in Kollam on December 5. Photo Courtesy: C. Sureshkumar
There was no time to fully process the disaster as the cause became clear – the massive reinforced soil (RS) wall had failed. Four vehicles, including a school bus, were trapped, although no one was injured in the incident.
“The sound started from a small hole in the wall of the RS next to the service road, which later turned into a huge crater. The culvert over the stream collapsed and soon, the surrounding ground, which extended to the paddy field, burst open with a bang. This was followed by a huge pipe burst, flooding the service road. Thankfully, the power supply was immediately cut off. Had the high wall collapsed completely, it would have fallen on the service road. Which would have turned into a major tragedy,” he says. Srijit S., resident.
The earlier collapse of the National Highway at Kuriyad in Malappuram is a clear example of the Mayilakkadu incident.
inadequate foundation
Engineering assessments confirm that the fundamental flaw is the same in both cases. In both Kuriyad and Mayilakkadu, collapses occurred because the underlying foundation was structurally inadequate to bear the imposed loads.
Construction work of an underpass on National Highway 544 is in progress at Amballur, Thrissur. The Mayilakkadu accident has created fear among residents of the area over the stability of the earth-filled structure being built for the underpass. , Photo courtesy: K.K. Najeeb
“It is a fundamental engineering principle that an embankment built on a weak foundation will collapse when the load on it exceeds its capacity. Raised earth embankments require rigorous soil testing, strengthening measures and foundation improvements to safely increase the load-bearing capacity. However, these necessary steps were neglected – neither necessary inspections were carried out nor the soil was strengthened,” said a member of Deshi Path Samara Samiti, Kottiyam, a group formed to protest against unscientific construction. Criticizes Ajitkumar. The base supporting the massive earth embankment at Mayilakkadu is marshy land, and officials conveniently ignored the sensitive terrain and high groundwater saturation of the area. He says that when the load exceeds the bearing limit of a weak foundation, failure is inevitable.
Senior geotechnical engineering consultant Jayakrishnan Menon confirmed that the wall was designed without addressing the low soil strength conditions of the site. “The coastal areas of Kerala have soft marine and alluvial deposits, unlike other states where large embankments are common. The Mayilakkadu fill has imposed loads far exceeding the shear strength of the weak subsoil,” he says. He emphasizes that inadequate geotechnical investigations led to poor understanding of the soil profile. To repair the present fault, the failed section must be removed, and the soil conditions must be scientifically re-established before reconstruction.
long term risk
He says solutions such as stone pillars are possible options, but can be employed only after detailed testing. “Inadequate soil reports pose long-term risks, as failures can occur years after construction. Accurate and truthful soil data is critical for safety in the geologically sensitive areas of Kerala,” he says.
According to the company in-charge of the construction, the ₹1,385 crore project involves upgrading a 31.25 km stretch of NH 66 from the existing two-lane road to a six-lane dual carriageway highway. This comprehensive development plan includes construction of one bypass, six flyovers, one rail overbridge, 10 underpasses, seven new major/minor bridges and 42 culverts for Kollam city. Achieving this goal requires massive earthworks, notably involving the excavation of over 2.5 million cubic meters of soil and the construction of over 100,000 square meters of reinforced earth wall.
“Construction of RS walls without considering the specific characteristics of topography, climate or soil of each location is unscientific, and should be stopped immediately. With the collapse of elevated roads built using RS walls at several places, it has been clearly proven that such structures are impractical for Kerala roads. Kollam MP NK Premachandran suggests that pillar-supported elevated highways should be constructed instead of relying on RS walls. should be constructed.”
failure of carrying capacity
Following the accident, the National Highways Authority of India (NHAI) has initiated a large-scale, state-wide geotechnical investigation. According to initial assessments, the failure was caused by deep-shear or bearing capacity failure, meaning the foundation soil was severely weakened and unable to support the imposed load of the wall and soil fill.
NHAI has temporarily suspended the project concessionaire and its promoters, M/s Shivalay and independent engineer, M/s Feedback-Satra JV, from bidding on future projects. It has also issued show cause notices to both parties regarding possible sanctions – up to three years for the concessionaire and two years for the independent engineer – besides imposing a fine.
To guarantee structural integrity, NHAI has mobilized 18 geotechnical agencies to conduct hardened soil sampling and testing at 378 RS wall locations at 18 NH 66 project sites in Kerala, including sites already constructed, in progress and yet to commence.
The Kottiyam Merchants Association is planning to launch a massive protest in view of the extensive damage caused to utility lines and service roads following the collapse. Association general secretary S. Palani demands, “With over 35 educational institutions and seven hospitals in the vicinity, Kottiyam is a high-traffic area with over 4,000 students commuting daily. The current construction is a direct threat to commuters. The dangerous wall between Mayilakkad and Parakkulam should be replaced with a stable, pillar-supported structure.”
Palani points out that the project has been plagued from the beginning by systemic violations, particularly the height of the wall, which exceeds legal safety limits. “We had warned the authorities about the impending disaster in the area. Apart from petitioning the state and central governments, we met officials of Shivalaya Construction Limited and told them that the soil conditions could not support the wall. Our repeated warnings were met with complete inaction, and the recent collapse is a direct result of that negligence. Public safety cannot be compromised, and accountability must be fixed,” he says.
Amballur residents worried
The Kottiyam accident has created fear among residents of Amballur in Thrissur district over the stability of an earth-filled structure being built for an underpass on National Highway 544. The underpass is being constructed in an extensive wetland area where soil has been filled and raised along the north-south axis for about 1.2 km. Residents allege that the natural east-west water flow has been disrupted, with no proper outlet provided to drain rainwater from the highway or water flowing from the eastern side. As a result, even slight rainfall leads to severe water-logging around the underpass and overbridge area, they complain.
“No proper and scientific study was conducted before starting the work on the Amballur underpass,” says T. Srinath, an activist of the Kerala Sastra Sahitya Parishad (KSSP).
At a special meeting of the Gram Sabha, officials were warned of the danger of flash floods if the project is implemented without adequate drainage plan. “Amballur is a flood prone area. If there are heavy rains, the situation will worsen as there is no way for the water to drain out,” he warned.
unscientific drainage system
According to residents, the existing drainage system along the highway is unscientific and unable to handle the intense rainfall. He says the problem has been compounded by the high, mound-like structure created by dumping large amounts of soil.
The water that once flowed through canals like Keli Thodu to the Kurumali River now has no clear outlet, as parts of these channels have been converted into roads. More than 60 houses are in the affected area besides commercial establishments, hotels and a cinema theater near Amballur Junction.
A study group led by the Nenmanikkara unit of KSSP found that the water flowing from the eastern side through the underpass and brought by the concrete canal on the western side of the highway is unable to flow towards the west due to the absence of proper channels. This situation has increased the risk of widespread flooding in the area.
Highlighting the similarity with the Kottiyam incident, KSSP’s KK Anish Kumar says the soil-filled structure is likely to suffer heavy waterlogging, which will affect its stability. He demands a comprehensive geotechnical study and safety audit of the Amballur underpass as well as other underpasses along NH 544 on the lines of the safety assessment conducted on NH 66.
Calling for immediate intervention, local residents say that alternative designs – such as column-supported underpasses without extensive soil filling – should be considered, especially in high-value (so that the area beneath the underpass can be used) and flood-prone areas, to allow natural water flow and reduce environmental and safety risks.
Crumbling roads and constructed walls along the newly developed National Highway stretches in Kerala have become a shortcut to accidents.
(With inputs from Mini Muringthery in Thrissur)
