Construction expert casts doubt on 'hong erosion' term in Lenteng Agung

JAKARTA, KOMPAS.com - Construction expert Davy Sukamta doubts claims that the collapse of Lenteng Agung Raya road in Jagakarsa, South Jakarta, was caused by underground hong or culvert structures eroded by age.

“There are statements claiming that old culverts have eroded. First, what does ‘eroded’ mean? If it’s a concrete culvert, how can it erode? If concrete culverts are eroded from the start, it’s not due to age,” Davy said when contacted by Kompas.com via phone on Friday (29 May 2026).

Davy said the exact cause of the road collapse should be determined by inspecting the construction type and damage on-site.

The term “hong” typically refers to clay pipes used in older water channels or simple culverts.

“We don’t know which is correct—round pipes or concrete box culverts,” he added.

If the road’s substructure is concrete, damage is usually caused by water seepage leading to rusted steel reinforcement, not merely age.

He also noted that previous road undulations should have been an early sign of issues with the ground or underlying structure.

“If a collapse occurs, the surface damage may be visible, so it’s better to excavate and inspect,” Davy said.

Previously, a section of Lenteng Agung Raya road towards Depok collapsed on Thursday (28 May 2026) at around 11:30 PM WIB. The sinkhole measured approximately 16 metres in length, 3 metres in diameter, and 3 metres deep.

As a result, traffic towards Depok was restricted to one lane until Friday afternoon, causing prolonged congestion.

Sartono, head of Jagakarsa’s Water Resources Agency (SDA), said a 3-metre hong crossing lies beneath the road.

“The cause appears to be a 3-metre hong crossing, which may have aged and eroded,” Sartono said at the scene on Friday.

Despite the collapse, Sartono confirmed that water flow connecting the UI’s PHB (interconnection channel) to Kalibata Ciliwung remained unaffected.

Crews deployed excavators to remove asphalt and soil debris blocking part of the channel.

“About a third of the hong may have collapsed, but it hasn’t blocked the water flow. The water continues, but a third is buried in soil. This will be cleared temporarily,” he said.

After cleaning, a third-party contractor will install a 2-metre high box culvert before road repairs commence.