THE use of clayey soil with gravel in the laying of roads is common in some Indian States, but no engineer has ever identified this as the reason for the bad condition of many roads. Research undertaken by the Roads and Buildings (R&B) Department in Guntur has resulted in the pioneering work of laying excellent roads for a stretch of 86 kilometres.
Superintending Engineer D. Bhavanna Rao is the man who has shown how sticking to construction norms and having proper knowledge about the materials used in road formation could save crores of rupees.
"The tendency among the people is to blame the engineer and adduce corrupt motives to him. There are black sheep in the profession, but in the majority of the cases, it is the ignorance of the executing agency and the inspecting engineer that leads to colossal waste of money," Bhavanna Rao said. His scientific analysis of the road conditions got accepted in an Indian Road Congress journal.
He identified the plasticity of clayey gravel as the single-most hindering factor in the laying of good roads. For the bonding of crushed stones, the load-bearing base and sub-base layers of a road should not have clayey soil. In the rainy season, when water enters these layers, the plasticity of the material does not allow proper bonding between compacted stone chips, leading to black-topped roads sinking in some places and bulging in others. In rural areas, tractors with iron wheels cut the thin bitumen-rich black-topped surface of the roads, and when they enter the fields from the sides they create craters, damaging the crust or providing a passage for the water to seep in. This results in reduced life of the road.
If the Guntur model is implemented, there could be a saving of 20 per cent of the funds used for repairing or re-laying roads and this would result in reduced frequency of repairs.
The R&B Department has recommended corrections in the engineering design and execution aspects to reduce damage to the slopes of irrigation canals and the roads on the bunds.Ramesh Susarla