Residents of Chennai were in for a surprise on Sunday morning when a a Honda City and a state-run bus fell into a massive sinkhole. This incident took place at Anna Salai, right in the heart of the city.
What happened here?
According to an eyewitness, the bus had stopped for passengers at a bus stop and a Honda City was going by when the road they were on caved in. The crater was so deep that the car can’t be seen, unless you come in close. The sink hole is about 5 mteres wide and 10 meters in length and is close to 2 meters deep, according to a statement issued by CMRL.
Close to 35 people were injured, but no one lost their life. The injured were rushed to Royapettah Government Hospital for treatment. The vehicles had to be pulled out using a crane. Post this, Chennai cops had cordoned off the Anna Salai road, which is an important road in the city. However the Finance Minister said that they will get the road fully functional by Monday.
Why did it happen?
The area where the incident took place had metro construction work going on. The area had been dug up to set tunnels for the metro.
In a statement, Sruthi Ravindran, a PRO at Chennai Metro Rail said
The cave-in must have taken place owing to the loose soil. Geographically, ours is loose soil. We have tried our level best to tunnel below 20 feet so it doesn’t disturb the upper layer of soil. However, metro pipelines and other road construction work makes the soil loose.
According to a press release:
The basic cause of today’s incident is due to the existing loose soil pocket along the tunnelling alignment. Where the tunnel boring machine (tbm) is under operation. CMRL has a strict instrumentation and monitoring of settlement/deflection due to the ongoing tunelling work. The monitoring point has been installed throughout the tunnel alignment at 10 meters interval. Continous reading is taken at every 6 hours interval to cross check any development done to the ongoing tunnelling work. The recent reading was taken around 2 pm just before the incident and there was no settlement recorded while taking the reading.
This is not the first time that such an incident was reported. On 30th March, the same stretch of road had caved in and it threw traffic out of gear. More incidents were reported in December 2015 at Teynampet when the road caved in due to metro construction as well. Another cave in was reported on Poonamallee High Road in June 2015, which was over 10 foot long.
But what about the rest?
Currently, there is a lot of metro work that is taking place in Chennai. Due to this sinkhole, they have stopped the tunneling work that is taking place at the Thousand Lights and AG-DMS stretch, to make sure that it was safe to continue. An inspection of the same area is set to take place post which the work will resume.