PUB links sewage shaft failure to Tanjong Katong sinkhole, calls safety time-out on works

SINGAPORE: A sinkhole that formed on Tanjong Katong Road South on 26 July 2025, swallowing a car, has been traced to a failure in an underground sewage shaft at a national water agency (PUB) worksite. At around 5.50pm on 26 July, a concrete caisson ring — part of a shaft under construction — failed at the worksite, PUB confirmed in a statement issued late on 27 July. Simultaneously, the road adjacent to the site collapsed, forming a large sinkhole that engulfed a black car.

Quick-thinking workers rescue driver from sinkhole

The driver of the car, a woman, managed to exit the vehicle and was pulled to safety by construction workers on site. Workers from Ohin Construction, who were stationed nearby, responded quickly upon hearing a loud sound. Site foreman Pitchai Udaiyappan Subbiah recounted that he and three others rushed to the scene and saw the car submerged in the sinkhole. “There was one car, and one woman was inside the car. I was thinking, somebody (fell) inside, I want to help,” he told reporters on 27 July. Subbiah instructed his team to throw the woman a nylon rope. Within five minutes, they successfully pulled her out. “One of my workers wanted to go down and help her, but I said they wouldn’t be able to climb out. So, I told them to throw her the rope first,” said Subbiah, a 46-year-old Tamil Nadu native who has worked in Singapore for 22 years. He added that the sinkhole had not yet filled with water at the time of rescue.

Rescue praised by public and SCDF

Initial statements by PUB had credited the Singapore Civil Defence Force (SCDF) for the rescue. However, SCDF later issued a Facebook update recognising the construction workers’ role, stating they would reach out to commend them for their bravery and prompt action. Following the rescue, the driver was conveyed conscious to Raffles Hospital for further checks. Mountbatten MP Gho Sze Kee visited the site the next morning and said the woman remained under observation for muscular pain. PUB later confirmed that the woman was able to walk and was undergoing additional medical evaluation.

Shaft construction linked to incident

The failed structure was part of a 16-metre-deep shaft meant to link three existing sewer lines beneath the area. Although the precise cause of the caisson ring failure remains under investigation, PUB stated that preliminary assessments have connected it to the sinkhole formation. The agency has since filled the shaft to stabilise the surrounding ground. Ground-penetrating radar scans were also conducted to evaluate nearby subsurface conditions, with PUB still analysing the data.

Safety time-out called across sewer projects

In light of the incident, PUB has declared a safety time-out across all similar sewer construction projects in Singapore. This move aims to reassess safety protocols and ensure structural integrity in ongoing and future tunnelling works. PUB is coordinating closely with the Land Transport Authority and the Building and Construction Authority to investigate the root cause and oversee repair operations.

Repairs and road closures underway

Following the incident, workers began pumping water from the sinkhole at 9.45am on 27 July, completing the task by 1.20pm. The car was hoisted out shortly after, at around 2pm. PUB reported that the sinkhole has been filled with liquefied stabilised soil to prevent further collapse. Road reinstatement works are set to commence thereafter. Until these are completed, Tanjong Katong Road South will remain closed between Mountbatten Road and East Coast Parkway. “Motorists and commuters are advised to plan their routes in advance and expect possible delays during the weekday peak periods,” PUB stated. The collapse disrupted water supply to 18 households approximately ten minutes after the sinkhole formed. PUB's initial findings suggest that water mains in the area were likely damaged due to ground movement linked to the sinkhole. Water supply was restored by 2.30am on 27 July after isolating the affected pipes. The agency added that the damaged pipes contributed to the rapid filling of the sinkhole with water, as seen in social media footage where water was observed gushing into the cavity and submerging the vehicle. Water stopped accumulating once the mains were shut off.

Commendation for workers' bravery

Singaporeans commended the swift actions of the workers, highlighting the danger posed by the unstable terrain. Videos also showed workers erecting barricades around the sinkhole shortly after the car was pulled out. Subbiah told reporters that after rescuing the woman, she informed them that her identity card and phone were still in the car. He lent her his phone so she could contact her daughter. “We saved a life… whatever happens, that is all that matters,” he said. PUB has apologised for the inconvenience caused by the sinkhole and road closures. It promised to continue updating the public on the progress of repairs and when the road will be safe to reopen.