A huge portion of the Poonamallee High Road caved in due to Chennai Metro Rail tunnelling work on Friday night.
The road gave away for a depth of about 4 feet, but as there was no traffic flow on the stretch at that time, no untoward incident took place, sources said. Moreover, the road caved on the margins, close to the pavement.
According to officials of the Chennai Metro Rail Limited (CMRL), the road caved in due to the ongoing tunnelling work near the nurses’ hostel of Madras Medical College and Hospital.
“Patchwork on the damaged spot was carried out immediately by our staff. There was no problem after that,” an official said, adding that sand bags and caution boards were placed around it.
Two tunnel boring machines (TBM) — used to drill tunnels to connect underground stations — have been drilling from Madras High Court and Chennai Central Metro Rail stations for several months now. So far, of the 1,320 metres that have to be excavated between these two stations, the TBMs have bored 800 metres.
“When the TBM’s routine maintenance work was carried out in the area on Friday night, the road caved in. Though we checked the parameters before the maintenance work, a part of the road caved in. Soon, the TBMs will resume work from this junction,” another official said.
This work is carried out as a joint venture between Afcons Infrastructure Limited and Transtonnelstroy Limited since 2012. This is not the first time a road on the Metro route has caved in due to tunnelling work as it has occurred on a few occasions earlier on the same road.
Chennai Metro Rail built at a cost of Rs. 14,600 crore covers 45 km of the city in phase I; of this, 24 km will be underground and the remaining 21 km elevated.
Patchwork on the damaged area was carried out; no problems after that, says official