Potholes and water stagnation are common during the monsoon, but with proper planning and maintenance, damage to roads can be avoided, say experts.
When water stagnates on an asphalt road, the aggregate layer (gravel or sand) separates from the bitumen (the binding material mixed with the aggregate to form the asphalt). This is how potholes form.
“Water is bitumen’s enemy,” says Sampath Kumar, former chief engineer of the highways department. Roads must have the right ‘camber’ (slope from the crown of the road to the side) to allow water to drain on to the sides, where it will be collected in stormwater drains.
According to V. Thamizharasan, former professor, transport engineering division of IIT-Madras, the problem begins with the laying of roads.
“Most roads in the city are bituminous stretches that have a life span of 12 years. Unless care is taken while laying the roads, water stagnation and other problems will occur,” he says.
Timely filling of potholes using bituminous binders have to be undertaken. “Care should be taken to see there is no water in the potholes when they are being filled,” he says.
Unless stormwater drains are cleaned regularly and the holding capacity of waterbodies is improved, water stagnation will continue to occur despite proper laying and maintenance of roads, says K.P. Subramaniam, former professor of urban engineering, Anna University.
“In Chennai, the main problem is the excess build-up in water bodies leading to slower flow of water,” he says.
Using geo-textiles to coat the roads during laying work, or even after, will help filter water and lead to effective drainage, he says. Temple tanks and other artificial collection centres developed across the city will also help to collect water, says Mr. Sampath Kumar.
