Subsidence in a busy street in the Indian city of Chennai that trapped a car has been attributed to tunnelling work for the new metro system.
The news of the collapse comes as the two elevated sections of the new metro system were opened today as tunnel continues on other sections of the 45km network.
An official statement from Chennai Metro Rail said that the collapse at the surface was caused by the tunnel boring machine (TBM) reaching a more challenging than expected change in ground conditions on the High Court to Chennai Central section of the new line.
“The TBM hit an uneven surface as the soil changed from rock to clay,” an official said.
The hole was backfilled with foamed concrete and the road was resurfaced before it was reopened just hours after the incident.
Local media reports suggest that the metro operator was aware of the issue several days before the collapse occurred as steel plates had been placed on the road near the position of the collapse and there had also been increased surveying activity.