Road caves in near Loyola College, sewage line blamed

CHENNAI: Hardly a year after Tank Bund Road was laid, a portion of it in front of Loyola College caved in on Wednesday. Traffic police alerted corporation officials on Thursday morning, who barricaded the space - which is about one square metre.
"We were informed in the morning and we inspected the site immediately. There was an old, rusted Metrowater sewage line underground. We assume it could have caused the soil to loosen. The top surface had collapsed. We have restored the road by closing the portion and have laid concrete over it," said an assistant engineer who was at the spot. The official said there were no traffic problems as it was safely barricaded. "After a week, we will open it for traffic. The concrete has to set and cure," said the official.
A senior corporation official said caving-in of roads is normal in coastal cities as the sub-soil is smoother. However, in this case, it was due to a faulty and abandoned Metrowater pipeline. Due to seepage, the soil had loosened and the road subsided as heavy vehicles passed over it.
"Whenever roads are laid, we only dig up to 40mm for laying bitumen. Pipelines are laid one metre below the road. So, it is difficult to spot them and check for leaks. As the probability is only 10%, this is not checked before roads are laid," said an official. The pipeline was about 20 years old.
"Also, roads don't get damaged immediately because of a leak. It happens over time. Sometimes, it is due to heavy vehicles and in certain cases, it's due to weak sub-soil."
In the last four years, several roads have caved in, including Rajaji Salai opposite Port Trust, Sivasami Road, Devanathan Salai, R K Mutt Road, Sardar Patel Road and those in other parts of the city. Several roads such as Anna Salai and Tailor's Road had caved in since metro tunnel work began.