Bengaluru: Not just on new roads, sinkholes are showing up everywhere

Experts said that even heavy rains can cause seepage, insisting that improvement in quality alone can stop damages

The sinkhole in the newly built service road of Kundalahalli underpass earlier this week did not seem like an isolated occurrence.

In fact, several smaller holes have been appearing on the city roads, which have gone unnoticed. Over the last one month, sinkholes were found on Cubbon Road, Kengeri Main Road, Sankey Road, BEL Road, among others, evidence that the roadwork in these places has been poor.

While Bruhat Bengaluru Mahanagara Palike (BBMP) officials asserted that most sinkholes had appeared due to seepage of water from underlying pipelines, experts felt better quality works could have prevented such mishaps.

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“While seepage of water could only be one of the reasons, shoddy work and failure to monitor the works is the major reason. Poor compaction during road-laying is the key reason for such incidents. BBMP engineers should hold regular inspections when the work is in progress instead of inspecting the quality after completion,” said Srikanth Channal, chairperson of the Association of Consulting Civil Engineers, Bengaluru.

Engineering defects

Explaining the vital role compaction plays in road-laying in Bengaluru, Dr P Anbazhagan, from the civil engineering department of Indian Institute of Science (IISc), said that the high silt content in Bengaluru soil calls for better compaction.

“The Bengaluru soil is high in silt content, which increases its tendency to flow along with water. When there is loss of silt, eventually, application of even small amounts of load will result in sinkholes,” Dr Anbazhagan said.

He suggested that the civic body could use ground-penetrating radars to identify cavities deep inside and prevent formation of such sinkholes in the future.

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Channal said the BBMP must ensure qualified engineers inspect the works to ensure road damages do not happen in future.

“Looking at the quality of works, it is evident that the engineers are not inspecting or verifying the works taken up by contractors. There are electrical, mechanical, and all other engineers looking at roadworks. We need specialised civil engineers to work on the field to identify such flaws,” he said.

Experts also added that even heavy rains can cause seepage, insisting that improvement in quality alone can stop damages.

Traffic slowdowns

Bengaluru Traffic Police (BTP) officials also confirm sinkholes are increasing. “These are more dangerous than potholes because they not only slow down traffic, but also cause grievous injuries. We have now barricaded these spots,” a senior traffic personnel told DH.

What is the difference?

A pothole occurs when a few layers of the road peels off and it widens into a crater.

A sinkhole appears when all the layers of the road cave in.