KOCHI: Following a deadly mudslide on the Kochi-Dhanushkodi National Highway (NH 85) that killed one person and destroyed eight homes near Adimali, experts are directly blaming the contractors working for the National Highways Authority of India (NHAI).
They argue that unscientific construction, especially aggressively cutting slopes during the rainy season, greatly increases the risk of landslides.
The government has responded by ordering a temporary halt to all work on the major NH 85 until further notice.
‘Wrong Way to Dig’ Geologists say the core mistake is the way the soil is excavated. Instead of following safety rules, contractors are widely using sheer vertical cutting—sometimes up to 20 meters high—without adding essential stability features. The proper way is to create steps, called benches, to manage the slope.
“They should have ideally used slope cutting with benches, rather than just vertical cutting,” says Dr. Sajin Kumar K.S., an assistant professor of geology at Kerala University.
Benching is crucial because it adds stability and reduces the chance of the hillside collapsing. However, contractors often put off protection measures until the end, vertically cutting the slope and then just covering it with a thin layer of shotcrete (sprayed concrete).
Dr. Kumar explained that the soil on these slopes is relatively young (10,000 to 15,000 years old) and doesn’t connect well with the ancient rock base (250 crore years old) underneath. Vertical cutting essentially removes the natural support and destroys the soil’s stability.
Rain Worsens the Problem The situation gets worse when rainwater soaks into the newly exposed vertical cuts, adding weight and pressure.
Experts also warn that quick fixes like retaining walls are likely to fail because of the huge pressure from water or poorly packed soil building up behind them. When the top layer of soft soil collapses, the hard rock beneath is often exposed, proving that the soft surface simply gave way.
Residents Blame Contractors Idukki: Residents of the Laksham Veedu Colony in Koompanpara said unscientific digging was the cause of the big landslide on Saturday. They said the 40-foot-high, steep ridge behind their homes was carved out during the highway expansion, making the slope unstable. “We told the officials many times. Cracks had started appearing weeks ago,” said resident Shaiju. A revenue official confirmed that the area had shown signs of soil movement earlier. Water Resources Minister Roshy Augustine, who visited the site, admitted the landslide was connected to the highway work. “A detailed inquiry will be done, and strict action will follow,” he promised.
With input from TNIE
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