'CT scans' to detect sinkholes? A Singaporean firm in China seeks to bring this technology home

CNA

2 days ago

SHENZHEN: Moving slowly along a quiet stretch of road, a sophisticated radar unit mounted on the back of a van is lowered close to the ground.
Its aim: to scan for and detect anomalies and underground risks before they become sinkholes.
A live feed streams from inside the vehicle.
It looks like a CT scan but instead of body parts, it reveals layers of soil, buried pipes and even cavities usually invisible to the naked eye.
'It's like a health checkup but for infrastructure,' said Zhi Haiyan, an engineer and founder of DECOD Science & Technology, a Singapore company now piloting the system in Shenzhen.
As sinkholes swallow roads from Singapore to Kuala Lumpur, Seoul, and cities across China, such emerging technology is at the forefront of the race to detect them before disaster strikes.
GLOBAL HOMECOMING
Founded in Singapore in 2003 with support from the Economic Development Board (EDB), DECOD has become widely recognised in China as a pioneer in ground-penetrating radar (GPR) technology.
Zhi was once described by state media outlet People's Daily as 'a leading figure' in advancing GPR technology across critical infrastructure sectors.
The 66-year-old was born in China and became a Singapore citizen in 2011. He graduated from Tsinghua University in 1983, majoring in Radio Technology and Information Systems.
Before founding DECOD, Zhi worked in China's aerospace sector on GPR research and development.
In 2022, he established a joint venture in Shenzhen to expand applications in the China market, with Singapore remaining the base for global expansion.
DECOD's 3D mobile GPR system is currently being piloted in Shenzhen's Guangming district, an area known for its vast nature and forest attractions.
A pilot trial began in the wake of a deadly expressway collapse in Guangdong last May, which killed 52 people and injured 30 others when a road section caved in during heavy rain.
Every day, for more than seven hours, DECOD's radar-mounted vehicles have been scanning roads throughout the district.
To date, the system has identified and flagged more than 100 underground anomalies including voids, delamination zones where structural layers have separated, and loose soil.
The company is also working with an airport group in western China to inspect over 30 runways.
It is collaborating with AI researchers to improve radar detection accuracy, Zhi said.
The goal is to train algorithms to automatically interpret radar scans and assign risk levels using GPS-linked, colour-coded visual outputs, he added.
'Eventually, we hope city officials can respond to alerts directly, without needing a technical team to interpret every scan.'
Following its success in China, the company is now turning its focus back to Singapore as it prepares for global expansion.
'Singapore's Smart Nation model is a great example of how infrastructure can be treated like a health checkup - problems can be discovered and fixed early,' Zhi said.
'We want to show that our radar system can be part of this diagnostic process.'
The company said that it is currently in talks with several Singapore agencies like the Land Transport Authority (LTA), Building and Construction Authority (BCA) and ST Engineering about possible pilot deployments involving routine road scans, underground structural monitoring, or integration with city planning systems.
'Singapore is an ideal prototype - it is small, dense, highly urbanised and forward-looking," he added.
"It is also internationally trusted, which matters if you are hoping to bring (your products) to global markets.'
'We want to help cities around the world monitor the health of their infrastructure," Zhi added.
"But we also want to show how powerful this technology can be when used preventively, not just reactively.'
"HEALTH CHECKUPS" FOR ROADS
Using advanced radar technology, anomalies and underground risks like loose soil or pipeline shifts can be detected beneath roads, highways, railways and even airplane runways early - without digging or disrupting traffic.
'We are just like doctors who use CT scans to see what's happening inside the body,' Zhi said. 'It's like … (how) you monitor a small tumour and act before it grows.'
'We use our radars to spot underground risks before they turn into disasters.'
The radar soon picks up a yellow signal and Zhi springs to life.
He soon calls over a technician and within minutes, a team is deployed, drilling into the site which revealed an underground void.
Data is logged, geotagged and uploaded to a cloud dashboard system that notifies Shenzhen emergency officials, Zhi said, allowing them to monitor high-risk sites in real time.
'Our system uploads real-time scan data to the cloud, building a database over time,' he added.
Unlike traditional GPR systems which require extensive processing and are only able to generate flat one-dimensional (1D) or two-dimensional (2D) readings and images, DECOD's system produces high-resolution 3D visuals in real time, showing the depth and width of underground anomalies like voids, loose soil or distorted pipelines.
Each scan can also be tailored based on depth and resolution.
Antennas detect underground objects up to five metres deep while the system's AI identifies patterns and produces colour-coded maps with risk indicators.
Blue denotes lower-risk areas, while yellow and red zones point to more serious structural risks.
Over time, the platform would be able to construct a 4D model of the site, tracking how subsurface conditions can evolve over days, weeks or months.
'Our greatest advantage is that we can see what others cannot,' Zhi said.
'This technology doesn't just tell you where the problem is, it gives you time to fix it before it becomes dangerous.'
AVERTING DISASTER
Sinkholes have been making global headlines, with cases reported in several densely populated, fast-growing Asian cities.
Their increasing frequency and severity highlight an alarming trend, experts said, renewing public concerns over infrastructure safety.
Dozens of sinkholes were reported in Seoul in 2023. In India, incidents have been recorded in megacities like Delhi and Mumbai, often after monsoon rains when floodwaters overwhelm urban drainage systems.
Last December, a deep sinkhole appeared in a village in southwest China's Guizhou province. In just over two years, the village saw more than 30 sinkholes, some as deep as three metres.
A nightmare eight-metre-deep sinkhole that opened beneath a pavement in Kuala Lumpur last August swallowed a 48-year-old tourist from India, sending search and rescue teams scrambling. Days later, a second sinkhole, believed to have been caused by a downpour, opened nearby.
In Singapore, a large sinkhole along Tanjong Katong Road on Jul 26 made national headlines and sparked public safety concerns and panic - a car had fallen in and its female driver had to be rescued by workers and taken to hospital.
Sinkholes rarely happen without warning, experts said, but in many cases, early signals go unnoticed - or worse, ignored.
'Some governments may not feel an urgency because these dangers are hidden," Zhi said.
"But by the time a collapse happens, it would already be too late.'
While the causes of individual incidents vary, the most common triggers are well known: leaking underground pipes, poor soil conditions, ageing infrastructure and weak inspection.
Nino Welland, a senior principal consultant at WSP, a Canadian engineering firm, said immediate causes of sinkholes often stem from poorly compacted fill or infrastructure damage.
'This can be either karst topography with ingress of water (where the dissolving of bedrock creates sinkholes) … or erosion of any poorly compacted fill beneath infrastructure with leaking water or sewer pipes,' he told CNA.
Construction - tunnelling, utility works and pile driving - can also quietly shift ground foundations or hollow out soil layers, creating hazards invisible from the surface, he added.
Wu Wei, a rock engineering expert and assistant professor at Nanyang Technological University (NTU), has developed a new solution with his team to detect underground activity.
Called seismic scattering, the method uses seismic waveforms and unsupervised machine learning to map out small-scale underground openings, even when masked by noise or complex subsurface conditions.
As climate risks increase and road infrastructures age, Zhi from DECOD believes it is no longer optional to monitor what lies beneath. Like regular medical health checkups, city councils must regularly manage roads, tunnels and utilities.
'In the past … everything had to be done manually, and progress was slow,' Zhi said.
'Now, things move much faster and I believe that with new technologies being introduced, we can quickly prevent potential disasters before they happen.'
In China, road infrastructure maintenance varies significantly by city and region - with some areas struggling to finance much-needed repairs.
In a 2024 commentary published in China Highway magazine, researchers from China's Highway Research Institute estimated that about 40 per cent of roads were due for maintenance but lacked funding, with a funding gap of around 50 per cent.
The shortfall is expected to widen as the road network continues to expand.
This technology could fill a gap, experts said, where current sinkhole detection models and methods have been shallow, destructive or limited to 2D imaging - making it harder to detect smaller underground risks.
Engineer David Ng, also chairman of the civil and structural technical committee at the Singapore's Institution of Engineers (IES), said advanced radar technology offers a broader view of what lies beneath the surface, areas typically covered by pavements or other structures.
'This technology (is a) non-destructive way of seeing the condition of the ground underneath pavements,' he said, adding that using 5G technology would allow for 'very fast access to the information'.
But even the clearest radar images would still need to be interpreted by professionals, said Welland.
'GPR 3D detection is useful but needs to be partnered with other investigation techniques, such as desktop study, local knowledge, geo mapping, gravity surveys and drilling,' he added.
'Only qualified engineering geologists should be used for interpretation and assessment.'
GPR technology performance could be compromised by issues like groundwater, Wu from NTU noted, recommending a combination of methods for better results.
For instance, techniques like seismic reflection - developed by his team - are effective at identifying deeper and larger subsurface structures, Wu said.
'Each method has its own strengths and weaknesses, so a combined approach is often the most effective,' Wu said, adding that integrating data from various sources to train AI models for sinkhole prediction holds promise, with early success already seen in landslide forecasting.