SINGAPORE, July 28 -- The sinkhole that appeared along Tanjong Katong Road South on July 26 likely did not form overnight, experts have said, following the collapse of two lanes which swallowed a car.

Although the incident seemed sudden, geotechnical specialists explained that the erosion causing the void beneath the road likely began earlier, according to a report published in The Straits Times.

"Sinkholes cannot form suddenly. They need time for the surrounding soil to wash away, causing the cavity to get larger and larger," said Associate Professor Wu Wei of Nanyang Technological University.

"This is happening underground, so we may not be aware of it," said David Ng, executive director of One Smart and chairman of the civil and str...