The collapse of a national highway stretch near Kottiyam in Kollam’s Mylakkadu area is due to ignoring the terrain and groundwater features, say experts. The site has weak, compressible soil and many water paths between the surrounding polders, which make it vulnerable to collapse when water soaks the ground. "It is a geotechnical failure because the low-strength soil conditions were not properly addressed during the design and construction process," said Jayakrishnan Menon, senior geotechnical engineering consultant. Kerala’s coastal and lowland soils are soft and behave very differently from soils in other Indian states. In one part of Mylakkadu, a 4 to 5-metre embankment was added, increasing load by about 10–11 tonnes per square metre. This was too heavy for the weak soil below. Mr. Menon explained, "When the applied load significantly exceeds the shear strength and bearing capacity of the underlying soil, failure becomes inevitable." Residents had repeatedly complained, warning that earth-fill embankments were unsuitable for Kerala’s wetland and monsoon-heavy environment. "We had requested them to abandon the unscientific earth-filling method and go for pillar-supported (viaduct) structures," said local resident Gireesh Babu. The contractor reportedly did not carry out proper soil studies before construction. Proper geotechnical investigation and soil analysis are needed. Mr. Menon said fixing such failures requires removing the bad soil and redoing detailed soil tests. For Mylakkadu, soil-improvement methods like stone columns might work, but only after confirming soil strength with proper tests. He stressed the danger of fake or incomplete soil reports, saying, "A failure can occur even five or six years later, long after the contractor’s liability period ends. That is why precise and truthful soil data is critical, especially in geologically sensitive regions like Kerala’s coastal belt."