Lenteng Agung Road Subsidence: Expert Says Concrete Cannot Suddenly Deteriorate

JAKARTA, KOMPAS.com - Construction expert Davy Sukamta has cast doubt on the initial assumption that the subsidence of Lenteng Agung Raya road in Jagakarsa, South Jakarta, was caused by deteriorated underground concrete structures or ‘hong’ decay due to age.

According to Davy, concrete cannot suddenly deteriorate if properly constructed from the start.

“If concrete is described as ‘keropos’, it was already degraded during casting. If it wasn’t degraded initially, suddenly becoming degraded is unusual. So the term might need clarification as to whether it’s truly degraded,” Davy said when contacted by Kompas.com via phone on Friday, 29 May 2026.

“Alternatively, if water seepage causes the rebar to rust, that makes sense. Rust leading to deterioration is plausible,” he added.

Davy stated that the exact cause of the road subsidence cannot be determined until an inspection of the underground structures is conducted.

According to him, it needs to be confirmed whether the underground construction consists of ‘hong’, concrete drainage channels, box culverts, or corrugated steel pipes.

“So we don’t even know which one it is. Whether it’s round pipes or concrete box culverts,” Davy said.

Davy explained that the term ‘hong’ generally refers to small-diameter clay pipes commonly used in old residential areas.

“In my view, it’s unlikely for a major road to use ‘hong’. It’s more likely to be corrugated steel or concrete box culverts,” he added.

Davy noted that road subsidence could be influenced by two factors: the strength of the subsoil and the strength of the underground construction structures.

“The subsoil must be strong before the construction can be strong,” he said.

He also observed that a previously undulating road surface could indicate underlying soil settlement.

“If the undulations are significant, it’s likely due to soil subsidence,” Davy said.