BENGALURU: In a shocking revelation, the series of recent landslides during heavy rain in the ghat sections and hilly country areas adjoining roads in Karnataka is being blamed on engineers not sticking to basic engineering principles rather than the common villain called deforestation. According to experts, engineers are not implementing what they studied in their semesters on road engineering.
While undertaking road widening works in the ghats, especially country roads (now part of state and national highways), the slopes need to be cut in such a way that the natural angles and inclines are not disturbed. But engineers cut them vertically. This loosens the soil and affects tree roots which hold the soil in place, in turn leading to landslides during heavy rain.
Prof G Madhavi Latha, Department of Civil Engineering, Indian Institute of Science (IISc), told The New Indian Express that while natural reasons also lead to landslides, there are engineering methods to check it, like nailing the soil, nets being anchored to slopes and ensuring plants/trees are not uprooted. Each terrain has a different solution, but it’s not implemented.
Engineering errors are found to be the cause of landslides. They do not check the slope angles. The materials used on hilly terrain to control landslides are also a problem. Ideally, rocks should be used, but due to availability and cost they are not. So a combination of clay and sand can be used, depending upon the region.
A senior National Highways Authority of India (NHAI) official, while requesting anonymity, admitted: “Slopes to grades must be maintained, but that is not done. Inspection of roads is also not being done,” the official said.
‘To avoid survey, works done on short stretches’
“Usually, whenever road works are done, especially in the ghats and highways, soil and geological experts’ survey is required. But now to avoid it, road works on short stretches are undertaken. These do not require surveys and if you observe such stretches — like Shiradi Ghat — they are seeing frequent landslides,” the official said. A PWD official admitted wherever there has been human intervention, there have been landslides. But ignoring basic road engineering principles is shocking behaviour on the part of the engineers concerned, he said. When a terrain is cut open for works, and plants and trees are uprooted, for the roots to take hold of the soil again takes up to 15 years. But no stretch is left untouched for so long and no time is allowed for nature to repair itself, as the roads are being constantly upgraded without adhering to basic road engineering principles, leading to landslides, he said.
The PWD and NHAI officials admitted that drains in road shoulders, which act as buffer and control friction, are no longer dug and maintained, which is also a reason for the landslides. Road engineer M N Srihari said, “Maintaining slopes and ensuring that natural pores are not disturbed are taught to engineers in the 6th semester of their engineering courses. But they do not implement it.”
Conservationists from Kodagu asserted that there has been no deforestation since 1994 in many parts of Western Ghats. Heavy rain does make the soil loose, but if proper slopes and roadside drains are maintained, water will flow and damage can be minimised, they felt.