Sinkholes Occurrence - Signals Need To Focus On Underground Infrastructure

GEORGE TOWN, Nov 11 (Bernama) -- The frequent occurrence of sinkholes in several cities, including Penang, in recent times has raised public concern, particularly among road users worried about safety risks.

The latest incident at Jalan Dato Ismail Hashim in Sungai Ara, Bayan Lepas, should serve as a reminder for all parties to take the management of ageing underground infrastructure more seriously.

Engineering expert Associate  Professor Dr Norhidayah Abdul Hassan recommended that the government establish a structured and risk-based underground utility asset management programme,  including comprehensive inspections of old pipes, as a national periodic initiative in major cities such as Penang.

Norhidayah, who is with the Pavement and Transportation Research Group (PTRG) at the Faculty of Civil Engineering, Universiti Teknologi Malaysia (UTM), said that ageing infrastructure should be assessed using modern techniques such as pressure leak tests and geophysical surveys to detect voids or ground support loss before structural failure occurs.

“To prevent recurring sinkhole incidents, the state government should also prioritise the upgrading of old pipelines in high-risk areas and enhance excavation work specifications,” she said.

“Apart from that, the Penang Water Supply Corporation (PBAPP), Indah Water Konsortium (IWK), Public Works Department (JKR) and local authorities (PBT) need to strengthen technical coordination so that leaks can be detected and repaired earlier,” she told Bernama.

Norhidayah also described the move by PBAPP and IWK to upgrade the old pipe network as the right move and in line with industry best practices.

This is because replacing old generation pipes with modern pipe systems can reduce the risk of leaks, increase the integrity of underground utility structures against external pressures such as traffic loads and soil conditions, she added.

She explained that the main cause of sinkhole formation in urban road areas is leakage from underground utilities, particularly water or sewer pipes, which gradually erode the supporting soil beneath the pavement.

“When leaks occur continuously, the flow of groundwater carries away fine particles from the base and subgrade layers, creating hidden cavities beneath the surface.

“As these cavities expand and the ground loses its supporting strength, the pavement layer can no longer bear the traffic load and eventually collapses, forming a sinkhole,” she said.

“This phenomenon is becoming increasingly common in densely populated urban areas due to ageing pipe networks, high traffic volumes, and soft alluvial soil conditions in coastal regions such as Penang, which are more prone to seepage and groundwater leakage,” she said.

She explained that many old pipes, which have been in service for more than 50 years, are made from outdated materials such as cast iron (CI) and asbestos cement (AC).

These materials are more susceptible to corrosion, joint cracking, and structural degradation, particularly in areas with soft alluvial soils and continuous exposure to traffic vibrations, she said.

Meanwhile, a senior lecturer at the Faculty of Civil Engineering, Universiti Teknologi MARA (UiTM) Shah Alam, Dr Nor Azmi Bakhary, suggested the establishment of a shared Geographic Information System (GIS) database for all underground utilities to improve coordination among agencies and strengthen standards for excavation and reclamation work.

He recommended implementing a phased replacement plan for old pipes and conducting transparent field audits, noting that such measures would not only enhance road user safety but also reduce future financial burdens.

“The ageing water and sewage pipe system, combined with inadequate field maintenance, accelerates the failure of soil structures. The state government should therefore introduce risk-based underground asset management and periodic monitoring using leak detection technology and Ground Penetrating Radar (GPR),” he said.

“The use of geosynthetic materials such as geotextiles and geogrids in road construction and repair can also reduce the risk of sinkholes,” he said.

The sinkhole on Jalan Dato Ismail Hashim, measuring 5 metres long, 3.5 metres wide, and 1.9 metres in diameter, last Nov 4, is believed to have been caused by a leaking pipe that allowed water to seep underground in the area.

Last Sept 21, a sinkhole also occurred on Jalan Burma in George Town when a 300-millimetre diameter pipe owned by IWK suddenly burst, causing severe damage to the road surface.

-- BERNAMA