Picture courtesy of MGR

 

Authorities discovered fresh signs of road swelling and water seepage on Samsen Road this morning, raising fears of another collapse just one day after a massive sinkhole opened nearby. The new bulge appeared in front of Boon Rawd Brewery, close to the Parliament building, around 2 kilometres from yesterday’s incident near Vajira Hospital. Traffic cones were placed at 08:30 on 25 September to block the area for safety.

 

The situation follows the dramatic road collapse on the morning of 24 September when a 30-by-30-metre sinkhole, more than 50 metres deep, suddenly formed outside Vajira Hospital and Samsen Police Station. That incident paralysed traffic, forcing authorities to close roads from Vajira intersection to Krung Thon Bridge and warn the public to avoid the area entirely. The collapse has been linked to the underground Purple Line rail tunnel construction and a major water pipe leak.

 

Prime Minister Anutin Charnvirakul, who is also the Interior Minister, inspected the damage on site yesterday. He stated that repairing the tunnel’s structural damage could take at least one year due to the complexity of the engineering work and the need to ensure safety. Experts from several agencies have confirmed that the collapse was caused by construction faults combined with the ruptured water pipe, which allowed massive amounts of sand and water to rush into the tunnel.

 

Bangkok Metropolitan Administration officials, together with the Mass Rapid Transit Authority of Thailand and other agencies, are now working to stabilise the ground. They have deployed tens of thousands of large sandbags, known as “Big Bags”, into the sinkhole to slow the soil movement and minimise further subsidence. The new bulging road section near Boon Rawd Brewery is under round-the-clock monitoring, with safety barriers in place to protect motorists and pedestrians.

 

The ongoing risk highlights concerns about the wider stability of Samsen Road’s underground infrastructure. Authorities continue to warn that further subsidence is possible and have committed to intensive 24-hour surveillance at affected spots. Longer-term repairs will focus on securing the damaged rail tunnel and ensuring the safety of surrounding areas.

 

 

 

Key Takeaways

 

• A new road bulge with water seepage was found on Samsen Road, 2 km from yesterday’s massive sinkhole.

• Experts blame the initial collapse on rail tunnel construction faults and a ruptured water pipe.

• Repairs to the tunnel could take at least a year, with emergency stabilisation measures ongoing.

 

Related Stories

 

Massive-road-collapse-near-Vajira-hospital-triggers-evacuation

 

Bangkok-sinkhole-battle-sandbags-used-to-halt-collapse

 

  Adapted by Asean Now from MGR 2025-09-25

 

 

 

 

3 minutes ago, Georgealbert said:

A new road bulge with water seepage was found on Samsen Road, 2 km from yesterday’s massive sinkhole.

 

What are the odds that it isn't "new", but they just take action now because of the other disaster?

 

Hasty sketch by a Thai friend who lives in the area. Her home is close by but not on the tunnel route.

 

15 minutes ago, Georgealbert said:

The new bulge appeared in front of Boon Rawd Brewery

I can help with the evacuation of Brewery, I have a big truck to offer if needed. 

I'd hate to see any beer going into a sinkhole. 

 

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4 minutes ago, SAFETY FIRST said:

I can help with the evacuation of Brewery, I have a big truck to offer if needed. 

I'd hate to see any beer going into a sinkhole. 

 

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Emptying the swimming pool now, you'll need somewhere to store it!!

And they just let the traffic keep going, including buses. I hope any future sinkhole knows not to spread beyond the coned off area.

For the first sink hole to collapse so fast, I'm assuming the sub-soil must have been washing into the tunnel for months, leaving a large void that finally caused the road to collapse.  So it's likely there are other voids under the road running above the tunnelling.

 

I bet they'd been pumping tons of mud out of the construction tunnel for ages, without realising they were undermining the road.

 

I wonder if the main contractor is the same as Rama II?

41 minutes ago, Kinnock said:

I wonder if the main contractor is the same as Rama II?

 

Civils are CH Karnchang and STECON.

3 hours ago, Crossy said:

Hasty sketch by a Thai friend who lives in the area. Her home is close by but not on the tunnel route.

 

 

 Purple Khlong Project?

 

 

 

 

UPDATE
Deputy BMA Governor: Samsen Road Seepage Unrelated to Sinkhole

 

Picture courtesy of ThaiRath 

 

Deputy Governor of Bangkok inspected a water seepage point on Samsen Road opposite Wat Chanthrasom School on 25 September 2025. Authorities cordoned off the area for safety while initial checks confirmed it was unrelated to the recent road collapse near Vajira Hospital.

 

The inspection took place at 11:30, led by Associate Professor Wisanu Sapsompol. The seepage was reported near Boon Rawd Brewery, raising concerns among local residents. Officials moved quickly to examine the cause and secure the site.

 

Wisanu confirmed that the water seepage is a separate incident from the Samsen Road collapse. He reassured the public that the road remains safe. Investigations are underway by the Metropolitan Waterworks Authority to determine whether the source is a water main or a drainage pipe.

 

To reassure the public, the Bangkok Metropolitan Administration’s Department of Public Works deployed ground-penetrating radar (GPR) equipment to check for voids beneath the road surface. The GPR sends electromagnetic waves underground, with reflections analysed to identify anomalies.

 

A leaking pipe was discovered, evacuated and has been successfully sealed. The road surface will be repaired to allow traffic to pass through on the evening of 25 September.

 

 

 

Key Takeaways

 

• Water seepage was confirmed unrelated to the Samsen Road collapse near Vajira Hospital.

• Authorities investigated the source and repaired the leak.

• Ground-penetrating radar tests were carried out to ensure road safety.

 

 

  Adapted by Asean Now from  Thairath 2025-09-25

 

 

 

 

3 hours ago, Kinnock said:

For the first sink hole to collapse so fast, I'm assuming the sub-soil must have been washing into the tunnel for months, leaving a large void that finally caused the road to collapse.  So it's likely there are other voids under the road running above the tunnelling.

 

I bet they'd been pumping tons of mud out of the construction tunnel for ages, without realising they were undermining the road.

 

I wonder if the main contractor is the same as Rama II?

 

 

If I'm not mistaken, a 6m Diameter tunnel had been excavated at depth - this encountered a structural failure during the construction process. 

Above this was a 1.4m diameter mains drainage (or water) pipe, which as a result of the 'main tunnel' collapse, also fractured, allowing water to 'wash away' the soft sediment into the void of the remaining collapsed tunnel. 

 

This is a risk of underground tunneling and is not isolated to Bangkok, but has also been encountered in Japan, Taiwan, KL, Singapore etc... 

 

 

Thus - there was 'no void' under the road - it was sound, until the 'tunnel itself' suffered a structural failure during the construction process - only then was the soil / substrate washed away under the road leading the collapse, and indeed build up of pressure (water) elsewhere in other areas.

I'm sure this has happened in our Western countries too....    As part of construction, its something that happens and is extremely difficult to mitigate against unless tunelling through far harder substrate (which Bangkok does not have).

 

 

22 minutes ago, richard_smith237 said:

This is a risk of underground tunneling and is not isolated to Bangkok, but has also been encountered in Japan, Taiwan, KL, Singapore etc... 

Agree. 

 

There was a recent Sydney tunnel collapse, I've heard that the project has been abandoned.... 

 

The M6 motorway tunnel project in Sydney has faced significant delays and suspensions due to two distinct sinkhole incidents in March 2024, which caused a partial collapse of a building and a separate land slippage within a contained construction zone. While the incidents were deemed not directly linked, they highlighted complex geotechnical challenges, leading to a halt in tunneling work for extensive safety and engineering reviews. The project's completion timeline is now uncertain, and a legal dispute between the government and contractor CPB over responsibility for the delays and costs is ongoing.