The story so far
On January 12, a motorist lost his balance and fell when a sinkhole appeared near Shoolay Circle on Brigade Road in the heart of Bengaluru city. Within a week of this incident, another massive sinkhole appeared in the western part of the city.
In the last few months, several sinkholes have appeared on Bengaluru roads. However, various civic agencies continue to blame each other, exposing their apathy towards the city.
The High Court of Karnataka on January 13 took suo motu cognisance of the formation of a sinkhole due to underground tunnelling work of the Namma Metro project on Brigade road.
The Bruhat Bengaluru Mahanagara Palike (BBMP), the city civic body responsible for taking care of the 1434.00 km arterial and sub-arterial roads in Bengaluru, blames the Bangalore Water Supply and Sewerage Board (BWSSB) for water pipe leakage or Bangalore Metro Rail Corporation Limited (BMRCL) construction works whenever sinkhole incidents get reported, while the BWSSB and BMRCL wash their hands off too, exposing the lack of coordination among civic agencies.
Civic authorities play the blame game
In the Brigade Road sinkhole incident, the two-wheeler rider, identified as Puneeth, suffered minor injuries. He was fortunate that other vehicles did not run over him. Puneeth received treatment at a private hospital and was discharged.
The BBMP blamed Namma Metro tunnelling work, which is underway below the road, for the sinkhole. The junction is along the Gottigere-Nagawara R6 underground Namma Metro line where tunnel boring machines are at work.
The BMRCL filled up the sinkhole with concrete by evening, but insisted that the underground tunnelling work was not responsible for the sinkhole. BMRCL Managing Director Anjum Parvez said, “The tunnelling work under the road has crossed the point where the sinkhole appeared over five days ago. Moreover, the tunnel under the road is going through a granite rock, and not through the soil. There are nearly three metres of rock over the tunnel. So, it is unlikely that the tunnelling work caused the sinkhole.”
On the other hand, Suguna Ramareddy, Chief Engineer, BBMP East zone, said, “Underground tunnelling work below the road caused the soil particles to loosen up, leading to a sinkhole.”
Just days after the Brigade Road sinkhole incident, on January 17, a sinkhole appeared at Mahalakshmi Layout in west Bengaluru following a water pipe leakage of BWSSB.
“The sinkhole appeared after the water started leaking from BWSSB pipes and the soil became loose,” a BBMP official said.
A BWSSB official said they are investigating the exact cause. “Preliminary investigation reveals that overload on the road might have caused damage to water pipes. We are replacing the pipeline and the sinkhole will be closed safely,” the official said.
What are the past incidents?
From January 2022 to January 2023, six incidents of sinkholes appearing on the roads have been reported in the city.
Apart from two incidents reported in January this year on Brigade Road and Mahalakshmi Layout, four cases of road caving took place in 2022. Here is a list of sinkholes that appeared on the city roads:
Sinkhole on road laid for Modi’s visit
In June 2022, barely days after many roads were given a facelift ahead of Prime Minister Narendra Modi’s visit to the city, a sinkhole formed on one of the newly-laid roads.
Following social media posts tagging the Prime Minister, the Prime Minister’s Office (PMO) sought a report from the BBMP and Karnataka government. Mr. Modi travelled by road on June 20, 2022. The sinkhole appeared on the road ahead of Nagarabhavi Circle near the Dr. B. R. Ambedkar School of Economics University, Bengaluru (BASE), a campus that the PM had inaugurated.
“There has been water leakage from a BWSSB pipeline that has loosened the soil, causing a sinkhole,” a senior engineer from the BBMP had said. However, a senior BWSSB official had claimed that their engineers had conducted a spot inspection and found no fault of theirs.
The BBMP had said they had spent ₹23 crores to redo 14 km of road, including the stretch that caved in, ahead of the PM’s visit.
Sinkhole on Kundalahalli Road
On October 9, 2022, a portion of the busy Kundalahalli Road in east Bengaluru caved in, resulting in a sinkhole a few feet wide, causing traffic to pile up until it was closed by the civic agencies.
The BBMP claimed that the road caved in after a water pipe leakage which led to seepage. “Water leakage from a BWSSB pipeline that had loosened the soil caused the sinkhole,” a BBMP official said.
A senior BWSSB official said a 450 mm Cauvery Water Main Pipeline had burst and created the sinkhole. This incident led to Cauvery water supply disruption in Munekolala, Thubarahalli, AECS Layout, BEML Layout, Kundalahalli and Kundalahalli Colony.
Road caves in near Sankey Tank
The busy road near Sankey Tank caved in on September 8, 2022. According to the BBMP, the sinkhole was the result of heavy rains in the city. “With the excessive rain, water carries soil particles to the lowest level, causing a cavity below the road surface,” officials had said.
Sinkhole appears in Kengeri
On the night of October 10, 2022, a road caved in after a BWSSB water pipe leakage in Kengeri. “Water leakage from the pipeline had loosened the soil and led to a sinkhole,” a BBMP official had said.
The BBMP asked the BWSSB to repair the road. A senior BBMP official said the BWSSB is responsible for repairs in such incidents. “All departments coordinate with each other, however, BWSSB has to repair the road after such incidents,” officials said.
Where are civic bodies failing?
In all these incidents, what has become clear is how the BBMP, BWSSB, BMRCL and other agencies don’t coordinate to resolve such road cave-in incidents in the city.
A senior BBMP official said that despite regular coordination meetings being conducted between civic agencies, whenever such incidents happen, the blame game starts. “We have clear instructions that whether it is a sinkhole or a road cutting by any agency, that agency will be responsible for resolution of the issues. They have to coordinate with BBMP and take action to resolve it. In the case of sinkholes, so far most of the sinkholes happened due to BWSSB water leakage and BMRCL underground metro construction,” a BBMP official told The Hindu.
What do experts say?
Experts say that the agencies do not take loose soil underneath the road seriously whenever they lay water pipes and during underground construction.
Road expert M.N. Srihari told The Hindu, “A soil test is very important before commencing any construction work underground and also laying water pipes. The loose soil underneath will be dangerous while tunnel boring machines (TBM) are used for underground metro construction work. The TBM vibration will create a sinkhole if there is loose soil. Hence, the soil test method is very important.
“After finding out there are chances of sinkholes or caves-in, the agency can use cement concrete to close such loose soil and make sure the road above will not cave in if a heavy vehicle goes on the road. The BWSSB should conduct regular thorough water-pipeline inspection across the water pipe network, ” he added.