Safety review at all road, rail sites after viaduct collapse kills 1, injures 10
Work at Upper Changi Road East suspended after accident leaves 1 worker dead, 10 injured
By Christopher Tan, Senior Transport Correspondent, The Straits Times, 15 Jul 2017
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Work at all public road and rail worksites was suspended for half a day yesterday after part of a new viaduct that was being built collapsed early in the morning, killing one worker and injuring 10.
The Land Transport Authority (LTA) used this "timeout" to review safety measures at all its rail and road projects all morning, before work resumed at 1pm.
Work remains suspended, however, at the $94.6 million project to build the viaduct in Upper Changi Road East, where a portion of the structure collapsed in the early hours of yesterday morning. The Building and Construction Authority revoked the permit for works at the project as the authorities conducted their investigations.
The project had been awarded to Or Kim Peow (OKP) Contractors, which was expected to complete it by the first quarter of 2020.
Shares of the mainboard-listed OKP crashed 8 per cent in the wake of the accident, before trading was halted at 10.15am.
OKP has been pulled up for safety lapses previously, and was blacklisted between January and April this year.
The latest accident took place at around 3.30am, when a portion of the structure collapsed. Eleven workers who had been working on it fell from a height of around 4m.
Work at Upper Changi Road East suspended after accident leaves 1 worker dead, 10 injured
By Christopher Tan, Senior Transport Correspondent, The Straits Times, 15 Jul 2017
The Land Transport Authority (LTA) used this "timeout" to review safety measures at all its rail and road projects all morning, before work resumed at 1pm.
Work remains suspended, however, at the $94.6 million project to build the viaduct in Upper Changi Road East, where a portion of the structure collapsed in the early hours of yesterday morning. The Building and Construction Authority revoked the permit for works at the project as the authorities conducted their investigations.
The project had been awarded to Or Kim Peow (OKP) Contractors, which was expected to complete it by the first quarter of 2020.
Shares of the mainboard-listed OKP crashed 8 per cent in the wake of the accident, before trading was halted at 10.15am.
OKP has been pulled up for safety lapses previously, and was blacklisted between January and April this year.
The latest accident took place at around 3.30am, when a portion of the structure collapsed. Eleven workers who had been working on it fell from a height of around 4m.
Preliminary investigations by the LTA showed that corbels - structures put in place to support the weight of precast beams between two sections - had collapsed.
A 31-year-old Chinese national was pronounced dead at the scene, while 10 others were taken to Changi General Hospital. Seven remained warded, with two in intensive care, while three were discharged after treatment.
OKP, which has been in construction since the 1960s, said in a statement to the Singapore Exchange that it was "deeply saddened" by the accident. It said it would "assist and cooperate fully with the authorities in their investigations".
Just three days earlier, OKP was fined $250,000 in connection with another incident on Sept 22, 2015. Four workers fell 6.4m after a section of the working platform they were standing on - under a flyover being constructed in Yio Chu Kang - became dislodged.
A 31-year-old Chinese national was pronounced dead at the scene, while 10 others were taken to Changi General Hospital. Seven remained warded, with two in intensive care, while three were discharged after treatment.
OKP, which has been in construction since the 1960s, said in a statement to the Singapore Exchange that it was "deeply saddened" by the accident. It said it would "assist and cooperate fully with the authorities in their investigations".
Just three days earlier, OKP was fined $250,000 in connection with another incident on Sept 22, 2015. Four workers fell 6.4m after a section of the working platform they were standing on - under a flyover being constructed in Yio Chu Kang - became dislodged.
Between January and April this year, OKP was put on a Ministry of Manpower blacklist after receiving 25 demerit points for lapses.
Yesterday's incident brought the number of reported worksite fatalities to 20 this year. There were 66 fatalities last year.
Second Minister for Transport Ng Chee Meng said yesterday's incident was very unfortunate, and he was "saddened" by it.
Second Minister for Transport Ng Chee Meng said yesterday's incident was very unfortunate, and he was "saddened" by it.
Speaking on the sidelines of the opening ceremony of the ninth Asean Schools Games yesterday, Mr Ng, who is also Minister for Education (Schools), said: "I have told LTA to extend the best assistance we can to the workers who are injured.
"Investigations are ongoing, the LTA is looking into what has happened together with the Ministry of Manpower, and we will get to the root of the causes so that we can learn the lessons to prevent another such incident from happening."
Meanwhile, the LTA is building a temporary road alongside the slip road below the viaduct which had been made impassable by debris after the collapse.
This is so that SBS Transit's bus service 24, which had been diverted because of the incident, can revert to its original route.
LTA added that it will carry out a thorough safety and design review of the temporary road before opening it for public use by noon today.
LTA added that it will carry out a thorough safety and design review of the temporary road before opening it for public use by noon today.
Or Kim Peow (OKP) Holdings' shares hit after accident at unit's worksite
Subsidiary was found guilty of safety breach in a 2015 worksite accident just three days before viaduct collapse
By Ng Jun Sen, The Straits Times, 15 Jul 2017
Or Kim Peow (OKP) Holdings' shares had soared some 45 per cent this year before losing 8 per cent yesterday to 39.5 cents before trading was halted less than six hours after the collapse of a structure at its subsidiary's Upper Changi Road East viaduct project site yesterday morning.
Brokerage KGI Securities last month had called the counter a "buy" given that OKP was in a good position to bid for contracts under the North-South Corridor project as it is a Building and Construction Authority-registered Grade 1 civil engineering contractor. Contractors with such a grading are not limited to project cost when bidding for public-sector civil engineering projects.
Yesterday's accident was the latest involving the firm's wholly owned subsidiary, OKP Contractors, which was found guilty of a 2015 safety breach, just three days before the structure collapsed.
In that case, one worker had died, while three others were injured after they fell more than 6m from a dislodged platform.
The firm failed to ensure the working platform erected by the company was safe for use. Mr Chan Yew Kwong, Ministry of Manpower's (MOM) director of occupational safety and health inspectorate, said of the firm then: "This is a clear case of a company that does not take workplace safety seriously.
"MOM will not hesitate to take punitive actions on companies and individuals who knowingly put workers at risk. There is no excuse for companies who fail to take ownership of workplace safety."
Before that incident, MOM had also hit the firm with 25 demerit points and blacklisted it from January to April this year, when it was barred from employing foreign workers. In its statement, OKP's group managing director, Mr Or Toh Wat, said it "deeply regrets" the accident.
The company had won the $94.6 million tender in November 2015 to construct a one-way, two-lane viaduct from the Tampines Expressway to the Pan-Island Expressway and Upper Changi Road East. Together with project consultants CPG Consultants, OKP was expected to complete the viaduct and the surrounding road works in early 2020.
As the client, the Land Transport Authority (LTA) maintains a site office at the worksite. Its officers were present when the accident happened.
According to LTA's website, OKP and CPG beat three other groups which had tendered bids ranging from $129.7 million to $193.7 million, for the project, two months after the fatal incident in 2015.
In 2015, LTA also awarded OKP two contracts worth $143.8 million to build more than 200km of new sheltered walkways around key public transport nodes by 2018.
OKP has an existing net construction order book of $306.1 million, excluding two new contracts worth $20.5 million awarded last month.
Founded by the Or family 50 years ago, OKP's board of directors include former minister of state for national development, communications and information technology John Chen Seow Phun, senior director of corporate law firm Niru & Co Nirumalan V. Kanapathi Pillai, and former president of the Institute of Certified Public Accountants of Singapore Tan Boen Eng.
Said Mr Or: "The (OKP board of directors) is deeply saddened by this unfortunate incident and wishes to express the company's heartfelt sympathies to the families of the deceased and others injured in the incident. Meanwhile, the group will ensure that the needs of the affected workers are fully taken care of."
The firm did not comment on its recent track record when asked.
The Building and Construction Authority (BCA) has instructed the project's qualified person (QP), from CPG, to inspect the remaining supporting structures at the viaduct. A QP is someone registered as either an architect or an engineer with the Board of Architects or Professional Engineers Board respectively. CPG declined to elaborate on the incident, but said it is "working closely with the relevant authorities to carry out detailed investigations".
BCA has also revoked the permit for the construction works, and "will be investigating the cause of the incident".
"As a safety precaution, the adjacent girders will be propped and supported," it said in a statement. "Nevertheless, we noted that the rest of the constructed viaducts are not above any public roads and will not pose a risk to the public."
As regulators of building and workplace safety, inspectors from BCA and MOM conduct spot checks from time to time.
Said an MOM spokesman: "MOM has issued a full stop-work order and is currently investigating the situation. MOM is also working with the Migrant Workers' Centre and the employer to render assistance to the workers and their families."
LTA lifted a "safety timeout" at all road and rail construction sites under the authority at 1pm yesterday following the accident.
Subsidiary was found guilty of safety breach in a 2015 worksite accident just three days before viaduct collapse
By Ng Jun Sen, The Straits Times, 15 Jul 2017
Or Kim Peow (OKP) Holdings' shares had soared some 45 per cent this year before losing 8 per cent yesterday to 39.5 cents before trading was halted less than six hours after the collapse of a structure at its subsidiary's Upper Changi Road East viaduct project site yesterday morning.
Brokerage KGI Securities last month had called the counter a "buy" given that OKP was in a good position to bid for contracts under the North-South Corridor project as it is a Building and Construction Authority-registered Grade 1 civil engineering contractor. Contractors with such a grading are not limited to project cost when bidding for public-sector civil engineering projects.
Yesterday's accident was the latest involving the firm's wholly owned subsidiary, OKP Contractors, which was found guilty of a 2015 safety breach, just three days before the structure collapsed.
In that case, one worker had died, while three others were injured after they fell more than 6m from a dislodged platform.
The firm failed to ensure the working platform erected by the company was safe for use. Mr Chan Yew Kwong, Ministry of Manpower's (MOM) director of occupational safety and health inspectorate, said of the firm then: "This is a clear case of a company that does not take workplace safety seriously.
"MOM will not hesitate to take punitive actions on companies and individuals who knowingly put workers at risk. There is no excuse for companies who fail to take ownership of workplace safety."
Before that incident, MOM had also hit the firm with 25 demerit points and blacklisted it from January to April this year, when it was barred from employing foreign workers. In its statement, OKP's group managing director, Mr Or Toh Wat, said it "deeply regrets" the accident.
The company had won the $94.6 million tender in November 2015 to construct a one-way, two-lane viaduct from the Tampines Expressway to the Pan-Island Expressway and Upper Changi Road East. Together with project consultants CPG Consultants, OKP was expected to complete the viaduct and the surrounding road works in early 2020.
As the client, the Land Transport Authority (LTA) maintains a site office at the worksite. Its officers were present when the accident happened.
According to LTA's website, OKP and CPG beat three other groups which had tendered bids ranging from $129.7 million to $193.7 million, for the project, two months after the fatal incident in 2015.
In 2015, LTA also awarded OKP two contracts worth $143.8 million to build more than 200km of new sheltered walkways around key public transport nodes by 2018.
OKP has an existing net construction order book of $306.1 million, excluding two new contracts worth $20.5 million awarded last month.
Founded by the Or family 50 years ago, OKP's board of directors include former minister of state for national development, communications and information technology John Chen Seow Phun, senior director of corporate law firm Niru & Co Nirumalan V. Kanapathi Pillai, and former president of the Institute of Certified Public Accountants of Singapore Tan Boen Eng.
Said Mr Or: "The (OKP board of directors) is deeply saddened by this unfortunate incident and wishes to express the company's heartfelt sympathies to the families of the deceased and others injured in the incident. Meanwhile, the group will ensure that the needs of the affected workers are fully taken care of."
The firm did not comment on its recent track record when asked.
The Building and Construction Authority (BCA) has instructed the project's qualified person (QP), from CPG, to inspect the remaining supporting structures at the viaduct. A QP is someone registered as either an architect or an engineer with the Board of Architects or Professional Engineers Board respectively. CPG declined to elaborate on the incident, but said it is "working closely with the relevant authorities to carry out detailed investigations".
BCA has also revoked the permit for the construction works, and "will be investigating the cause of the incident".
"As a safety precaution, the adjacent girders will be propped and supported," it said in a statement. "Nevertheless, we noted that the rest of the constructed viaducts are not above any public roads and will not pose a risk to the public."
As regulators of building and workplace safety, inspectors from BCA and MOM conduct spot checks from time to time.
Said an MOM spokesman: "MOM has issued a full stop-work order and is currently investigating the situation. MOM is also working with the Migrant Workers' Centre and the employer to render assistance to the workers and their families."
LTA lifted a "safety timeout" at all road and rail construction sites under the authority at 1pm yesterday following the accident.
PIE work site collapse: Workers were nearly finished with task
They fell 4m to the ground when beam on which they were standing collapsed
By Zaihan Mohamed Yusof, Melissa Lin and Seow Bei Yi, The Straits Times, 15 Jul 2017
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It was the wee hours of the morning and the workers were almost done with casting the deck of a new viaduct using cement.
They were supposed to pour 60 cubic m of cement onto a slab and had just 10 cubic m to go when the beam they were standing on collapsed, sending them falling 4m to the ground.
The incident at 3.30am yesterday at a viaduct in Upper Changi Road East left Chinese national Chen Yinchuan, 31, dead and 10 others injured. The workers were employed by subcontractors of construction firm OKP Contractors. One of the injured workers was from Transit- Mixed Concrete, while the other 10 workers were from Tongda Construction & Engineering.
An employee of Tongda, who declined to be named, told The Straits Times at its Ubi office: "According to my boss, they had almost finished. There was just another 10 cubic m (of cement) to go."
They fell 4m to the ground when beam on which they were standing collapsed
By Zaihan Mohamed Yusof, Melissa Lin and Seow Bei Yi, The Straits Times, 15 Jul 2017
They were supposed to pour 60 cubic m of cement onto a slab and had just 10 cubic m to go when the beam they were standing on collapsed, sending them falling 4m to the ground.
The incident at 3.30am yesterday at a viaduct in Upper Changi Road East left Chinese national Chen Yinchuan, 31, dead and 10 others injured. The workers were employed by subcontractors of construction firm OKP Contractors. One of the injured workers was from Transit- Mixed Concrete, while the other 10 workers were from Tongda Construction & Engineering.
An employee of Tongda, who declined to be named, told The Straits Times at its Ubi office: "According to my boss, they had almost finished. There was just another 10 cubic m (of cement) to go."
Mr Chen had arrived in Singapore for work in April this year. Records showed that he had been certified "competent" after he was assessed on April 24 for a workers' construction safety orientation course.
The Tongda employee repeatedly asked about the condition of the other workers, most of whom are believed to be in their early 20s.
"Is everyone okay?" the employee asked. "I am concerned about the workers right now because I am quite close with the supervisor who is now in ICU (intensive care unit)."
The injured included site supervisor Gao Liqin from China, whose right hip was impaled by a reinforcement bar.
The Tongda employee said: "I am close to some of the workers, not that I always see them, but I have been working at the company for some years." He said the company boss had called yesterday morning to say the beam had "gone down".
When contacted, the employee's superior said he had "no time to talk" and hung up.
At the accident site, a worker said the injured included a man who broke his leg, and another who was impaled.
The hours following the incident saw grim, frenzied activity in Upper Changi Road East. Police and Singapore Civil Defence Force (SCDF) personnel were seen rushing around at 4.30am, with SCDF's Disaster Assistance and Rescue Team officers present as well. They were conducting a search in the rubble and used search dogs as well.
Most of the workers at the scene had rushed down from their dormitories to check on their friends after learning of the accident.
The 10 injured workers were taken to Changi General Hospital. As of 7am, search and rescue operations had been completed.
Residents at a nearby block reported hearing a loud noise, but many were unaware of the extent of the accident. "There was a notice to say they would be working in the night for two days this month, so I didn't think too much about it," said Ms Koh Geok Lan, 60, who lives across the accident site, at Block 346, Tampines Street 33.
But in the morning, she realised the structure connecting the uncompleted bridge was gone. "The red structure (connecting the uncompleted parts of the bridge) had been up for a while, and I have seen many men working on top of it every day," said Ms Koh.
Ms Shriya Sriram, 20, a university student who lives in the same block, said: "It was a very loud sound - there was a screech. It was very metallic-sounding, but I assumed that they were moving something and it dropped."
Ms Shriya Sriram, 20, a university student who lives in the same block, said: "It was a very loud sound - there was a screech. It was very metallic-sounding, but I assumed that they were moving something and it dropped."
Pre-dawn work common to avoid traffic disruptions
By Ng Jun Sen, The Straits Times, 15 Jul 2017
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There was nothing unusual about the early morning construction work at the site where part of the structure collapsed yesterday. The Land Transport Authority explained that the timing had been scheduled.
To facilitate the works, a slip road from the Pan-Island Expressway to the Tampines Expressway (TPE) and Upper Changi Road North and East was closed between 1am and 5am on several days in the past three months.
The Straits Times understands that some roadworks have to take place in the early hours of the morning as it might be the only available time for certain major operations such as concrete casting.
Closing the slip road at night would allow heavy equipment to deliver construction materials to the work site without disrupting daytime traffic.
Pre-dawn works are a common practice in the construction industry, though there may be some additional challenges, such as the lack of light.
Singapore Contractors Association president Kenneth Loo said: "Certainly, there are more challenges to working at night, but it is possible to plan for them, for example by scheduling night shifts and having flood lights."
For works occurring at night, there will be stricter noise control requirements to reduce disruption to residents.
Fatigue levels of those working in these shifts should also be accounted for, as outlined in the Workplace Safety and Health Guidelines on Fatigue Management.
By Ng Jun Sen, The Straits Times, 15 Jul 2017
To facilitate the works, a slip road from the Pan-Island Expressway to the Tampines Expressway (TPE) and Upper Changi Road North and East was closed between 1am and 5am on several days in the past three months.
The Straits Times understands that some roadworks have to take place in the early hours of the morning as it might be the only available time for certain major operations such as concrete casting.
Closing the slip road at night would allow heavy equipment to deliver construction materials to the work site without disrupting daytime traffic.
Pre-dawn works are a common practice in the construction industry, though there may be some additional challenges, such as the lack of light.
Singapore Contractors Association president Kenneth Loo said: "Certainly, there are more challenges to working at night, but it is possible to plan for them, for example by scheduling night shifts and having flood lights."
For works occurring at night, there will be stricter noise control requirements to reduce disruption to residents.
Fatigue levels of those working in these shifts should also be accounted for, as outlined in the Workplace Safety and Health Guidelines on Fatigue Management.
Seven workers admitted to hospital; two in intensive care
By Tan Tam Mei and Seow Bei Yi, The Straits Times, 15 Jul 2017
One of the two workers seriously injured when an uncompleted highway structure collapsed in the wee hours yesterday was impaled through his hip by a reinforcing bar.
The Straits Times understands that he was still in surgery yesterday evening at Changi General Hospital (CGH) and had been warded in the intensive care unit (ICU) along with another worker, whose injuries were unknown.
Both were hurt when an incomplete road viaduct linking the Tampines Expressway to the Pan-Island Expressway collapsed, leaving 10 injured and one dead. All 10 were taken to CGH, with seven admitted and three discharged after receiving treatment, said a CGH spokesman.
The affected workers came from Bangladesh, China and India, and were aged between 22 and 49.
The worker who died was identified as Chinese national Chen Yinchuan, 31. He had arrived in Singapore to work just three months ago, in April. ST understands that the two men in the ICU are Bangladeshi worker Alam Shah and Chinese worker Gao Liqin, whose right hip was impaled.
The affected workers were employed by three different companies. These companies were sub- contractors on the worksite, said Mr Yeo Guat Kwang, chairman of the Migrant Workers' Centre, which had a team at the hospital to assist the workers.
Mr Yeo said that all three employers had provided the necessary guarantees to CGH to bear the treatment costs for their workers, or were in the process of doing so.
The employer of the dead worker was also making plans with the Chinese Embassy here to facilitate repatriation arrangements.
Yesterday afternoon, Minister of State for Manpower Sam Tan and Senior Minister of State for Transport Lam Pin Min visited the injured workers at CGH.
By Tan Tam Mei and Seow Bei Yi, The Straits Times, 15 Jul 2017
One of the two workers seriously injured when an uncompleted highway structure collapsed in the wee hours yesterday was impaled through his hip by a reinforcing bar.
The Straits Times understands that he was still in surgery yesterday evening at Changi General Hospital (CGH) and had been warded in the intensive care unit (ICU) along with another worker, whose injuries were unknown.
Both were hurt when an incomplete road viaduct linking the Tampines Expressway to the Pan-Island Expressway collapsed, leaving 10 injured and one dead. All 10 were taken to CGH, with seven admitted and three discharged after receiving treatment, said a CGH spokesman.
The affected workers came from Bangladesh, China and India, and were aged between 22 and 49.
The worker who died was identified as Chinese national Chen Yinchuan, 31. He had arrived in Singapore to work just three months ago, in April. ST understands that the two men in the ICU are Bangladeshi worker Alam Shah and Chinese worker Gao Liqin, whose right hip was impaled.
The affected workers were employed by three different companies. These companies were sub- contractors on the worksite, said Mr Yeo Guat Kwang, chairman of the Migrant Workers' Centre, which had a team at the hospital to assist the workers.
Mr Yeo said that all three employers had provided the necessary guarantees to CGH to bear the treatment costs for their workers, or were in the process of doing so.
The employer of the dead worker was also making plans with the Chinese Embassy here to facilitate repatriation arrangements.
Yesterday afternoon, Minister of State for Manpower Sam Tan and Senior Minister of State for Transport Lam Pin Min visited the injured workers at CGH.
Dr Lam later said in a Facebook post that the Transport Ministry was in touch with the workers' families and would provide the necessary assistance.
Yesterday's incident brought the number of reported worksite fatalities to 20 this year. There were 66 fatalities last year.
Human error looms large as possible cause of work site collapse near PIE
Experts point to a number of likely reasons for the corbels giving way
By Christopher Tan, Senior Transport Correspondent, The Straits Times, 15 Jul 2017
In most construction failures, human error ranks high as a probable cause. Yesterday's worksite collapse in Upper Changi Road East is unlikely to be an exception.
Local listed construction firm Or Kim Peow (OKP) was casting a section of the viaduct adjacent to a slip road from Upper Changi Road East to the Pan-Island Expressway when it gave way, killing one worker and injuring 10.
OKP, which clinched a $94.6 million contract to build the viaduct in November 2015, was scheduled to complete it by the first quarter of 2020. If it was falling behind schedule, as is the case with a number of other infrastructural projects here, it was not apparent. The worksite had a clean safety record until yesterday.
While the risk of accidents happening tends to increase if a builder is rushing, it exists even if a builder is well on time.
Lapses in design, work processes, supervision, procurement of materials and safety protocols would inevitably have been some of the many failures unearthed by investigators in past incidents.
In the case of the Nicoll Highway cave-in of April 2004 - which claimed four lives - persistent ground movements were systematically ignored during the construction of MRT's Circle Line.
Among several wilful missteps, a public inquiry found that the builders were adjusting the parameters of ground movement readings so as to be able to continue working.
While accidents are not always avoidable, they come under an unnatural glare in well-regulated Singapore when a road caves in or a viaduct collapses.
Especially when it appears that the industry, and indeed the regulatory regime, has not learnt from recent past mistakes.
In the case of yesterday's tragedy, preliminary investigations found that failed corbels were responsible for the viaduct section collapsing. But why or how did the corbels give way?
Engineering experts point to a number of possible reasons.
Former Institution of Engineers Singapore president Chong Kee Sen said corbels should be able to carry the weight of the viaduct section, with some of the load being shared with scaffolds and other supporting structures on the ground.
Experts point to a number of likely reasons for the corbels giving way
By Christopher Tan, Senior Transport Correspondent, The Straits Times, 15 Jul 2017
In most construction failures, human error ranks high as a probable cause. Yesterday's worksite collapse in Upper Changi Road East is unlikely to be an exception.
Local listed construction firm Or Kim Peow (OKP) was casting a section of the viaduct adjacent to a slip road from Upper Changi Road East to the Pan-Island Expressway when it gave way, killing one worker and injuring 10.
OKP, which clinched a $94.6 million contract to build the viaduct in November 2015, was scheduled to complete it by the first quarter of 2020. If it was falling behind schedule, as is the case with a number of other infrastructural projects here, it was not apparent. The worksite had a clean safety record until yesterday.
While the risk of accidents happening tends to increase if a builder is rushing, it exists even if a builder is well on time.
Lapses in design, work processes, supervision, procurement of materials and safety protocols would inevitably have been some of the many failures unearthed by investigators in past incidents.
In the case of the Nicoll Highway cave-in of April 2004 - which claimed four lives - persistent ground movements were systematically ignored during the construction of MRT's Circle Line.
Among several wilful missteps, a public inquiry found that the builders were adjusting the parameters of ground movement readings so as to be able to continue working.
While accidents are not always avoidable, they come under an unnatural glare in well-regulated Singapore when a road caves in or a viaduct collapses.
Especially when it appears that the industry, and indeed the regulatory regime, has not learnt from recent past mistakes.
In the case of yesterday's tragedy, preliminary investigations found that failed corbels were responsible for the viaduct section collapsing. But why or how did the corbels give way?
Engineering experts point to a number of possible reasons.
Former Institution of Engineers Singapore president Chong Kee Sen said corbels should be able to carry the weight of the viaduct section, with some of the load being shared with scaffolds and other supporting structures on the ground.
Mr Chong said it was possible for an "unforeseen impact load" to overwhelm the corbels as well as the other supports. This could be owing to overloading, ground movements or other construction activities.
Vertes Technologies director Chiam Soon Kiam said the corbels - made of reinforced concrete - might not have been given enough time to strengthen after they were cast.
Singapore Contractors Association president Kenneth Loo said that in most cases, concrete would take 28 days to reach its full strength, although contractors might take samples of the concrete on the seventh day to determine if it is strong enough.
A veteran civil engineer told The Straits Times that corbels are usually "extremely strong structures" which do not give way "just like that".
So, what caused them to give way?
"There could have been an error in the design, or the structures were not constructed to design specifications," the engineer, a member of the Institution of Engineers, Singapore, ventured.
Either of these could have happened despite the stringent checks and counter-checks in place, where civil work designs are scrutinised and signed off by independent qualified third parties.
"In some cases, temporary structures are not allowed to rest on corbels," the engineer said.
"This is because when concrete is being cast, it does not have any strength, and the whole thing becomes dead weight. The moisture of uncured concrete also adds to this weight."
"To be fair, we don't know at this point if this was the case," he noted.
So, what caused them to give way?
"There could have been an error in the design, or the structures were not constructed to design specifications," the engineer, a member of the Institution of Engineers, Singapore, ventured.
Either of these could have happened despite the stringent checks and counter-checks in place, where civil work designs are scrutinised and signed off by independent qualified third parties.
"In some cases, temporary structures are not allowed to rest on corbels," the engineer said.
"This is because when concrete is being cast, it does not have any strength, and the whole thing becomes dead weight. The moisture of uncured concrete also adds to this weight."
"To be fair, we don't know at this point if this was the case," he noted.
Another possible reason for the structural failure is ground movement.
"If the temporary structure was supported by ground structures and, if the ground sank, it could cause a collapse," he said, but noted that builders would have also tested the ground for stability before setting up the supports.
Asked if workers are supposed to be on top of a structure when it is being cast, the civil engineer said: "On paper, they are not supposed to be, for safety reasons. But in practice, it is usual for men to carry out checks during casting to spot and rectify any mistakes along the way."
If what these experts are saying holds water, human error as a root cause looms large once again.
Additional reporting by Ng Jun Sen
If what these experts are saying holds water, human error as a root cause looms large once again.
Additional reporting by Ng Jun Sen
PIE work site collapse: Questions loom over collapse of viaduct segment
The collapse of a 40m segment of a viaduct being constructed in Upper Changi Road East killed one worker and injured 10 others on Friday. While the authorities are investigating the accident, questions have been raised about the tender process and the design of the project. Correspondents Ng Jun Sen and Zaihan Mohamed Yusof attempt to answer the questions raised.
The Sunday Times, 16 Jul 2017
Q Why did the Land Transport Authority (LTA) award the contract to build the PIE-TPE viaduct to Or Kim Peow (OKP) Contractors? Was it based on OKP's lowest bid?
A With a bid of $94.6 million for the tender, OKP submitted the lowest bid for the Design and Build contract in November 2015, which was 27 per cent lower than the next lowest bid of $129.7 million by Yongnam Engineering.
But an LTA spokesman said it considers more than just price in assessing tender proposals, citing other "quality aspects", such as the relevant experience of the participating contractors, their safety management systems and practices, track record, project-specific technical, risk management and resource management proposals.
"All these quality aspects would be considered together with the price proposal to determine the award of the tender," he added.
For all construction tenders, the price-quality method is used by agencies as a framework. The price-quality weighting used for Design and Build projects before January last year is between 60:40 and 70:30.
An OKP spokesman said that despite its lower bid relative to the competition, there was "no compromise on the project's safety".
"With more than 50 years' track record in the industry, we are committed to ensuring project quality and workplace safety for projects that we undertake. For every tender bid that we participate in, we will evaluate and submit a bid which we feel is competitive and offers us reasonable profit margins."
Q Why was OKP, which was given 25 demerit points by the Ministry of Manpower (MOM) and blacklisted for three months earlier this year, allowed to work on a government project?
A In September 2015, OKP was involved in an incident in which one worker was killed and four injured after they fell more than 6m from a dislodged platform. The firm was found to have breached the Workplace Safety and Health Act for failing to ensure the working platform erected was safe for use.
According to the MOM website, 25 demerit points are issued to contractors for an accident that leads to death of one person. The points were given this January after the firm was prosecuted in court.
The Straits Times understands that when OKP was awarded the tender, its involvement in the 2015 fatal incident was still being investigated. OKP and one of its site supervisors were convicted of safety breaches only last Tuesday.
Firms that accumulate 25 points will be blacklisted for three months, which bars the contractor from bringing in foreign workers as all work passes will be rejected by MOM during the blacklist period.
They will still be allowed to renew passes for existing workers.
But Lian Beng construction manager Shie Chee Hwa said being on the MOM blacklist has the effect of limiting the firms' ability to tender for new projects. He said: "They will face more targeted and unannounced spot checks for their existing projects too, which can be several times in a month."
But he added that firms can still bid for public sector projects with their existing workforce, though they would have the spectre of the blacklist hanging over them.
Q Why did the corbels holding up the rest of the structure give way?
A The use of corbels in building elevated roads is a standard practice here and around the world, said Mr Chong Kee Sen, former president of the Institution of Engineers, Singapore.
Corbels are support structures designed to hold only a temporary load at the early construction stage, sharing the load with the rest of the scaffolding. When the concrete in the rest of the structure has set, it becomes self-supporting and most of the load is lifted from the corbels, he said. "During construction, corbels are designed to factor in the amount of load that engineers foresee it will carry during this phase, with around 10 per cent tolerance for the typical load it is expected to take."
Foreseeable activities include the weight of the concrete as well as all additional manpower and equipment needed on top of the structure. The task of calculating the load factors falls on the designers or engineers, which in this case will refer to CPG Consultants.
Mr Chong said corbels can fail in scenarios such as ground movements, overloading or design flaws, though he warned against jumping to conclusions before the investigations are complete.
Q What are the measures in place to prevent workplace deaths?
A While there have been 21 workplace deaths this year, only four occurred in the construction sector. There were 66 workplace accidents last year.
MOM conducts more than 6,000 worksite inspections every year, with some firms selected more than others, its spokesman said.
Those found with safety breaches will be taken to task, as "employers bear primary responsibility for managing risks at work and have to take full ownership of the safety and health matters of their employees".
In OKP's case, MOM officers had stepped up inspections on OKP's worksites after the 2015 accident.
Said the spokesman: "Our officers identified minor WSH (workplace safety and health) infractions on OKP's worksites, and have worked with OKP to rectify them immediately."
The last time MOM inspected OKP's worksite at the flyover viaduct was on April 3 - the day before it was removed from the blacklist, he revealed. At the time, the beams and deck slabs had not been installed at the site where the accident occurred. No infringements were found, said the spokesman.
Q Why did LTA stop work at all its worksites for half a day, and what was done during this time?
A All public road and rail worksites under LTA had to observe a "safety time-out" on Friday after the accident, according to its statement.
The Straits Times understands that the time-out ended around 1pm after all contractors carried out a voluntary review of their safety practices.
The Workplace Safety and Health Council has led several planned safety time-outs after a spate of accidents or dangerous occurrences. A time-out differs from a stop-work order, which only MOM can issue and was meted out on the Upper Changi Road East site on Friday.
The collapse of a 40m segment of a viaduct being constructed in Upper Changi Road East killed one worker and injured 10 others on Friday. While the authorities are investigating the accident, questions have been raised about the tender process and the design of the project. Correspondents Ng Jun Sen and Zaihan Mohamed Yusof attempt to answer the questions raised.
The Sunday Times, 16 Jul 2017
Q Why did the Land Transport Authority (LTA) award the contract to build the PIE-TPE viaduct to Or Kim Peow (OKP) Contractors? Was it based on OKP's lowest bid?
A With a bid of $94.6 million for the tender, OKP submitted the lowest bid for the Design and Build contract in November 2015, which was 27 per cent lower than the next lowest bid of $129.7 million by Yongnam Engineering.
But an LTA spokesman said it considers more than just price in assessing tender proposals, citing other "quality aspects", such as the relevant experience of the participating contractors, their safety management systems and practices, track record, project-specific technical, risk management and resource management proposals.
"All these quality aspects would be considered together with the price proposal to determine the award of the tender," he added.
For all construction tenders, the price-quality method is used by agencies as a framework. The price-quality weighting used for Design and Build projects before January last year is between 60:40 and 70:30.
An OKP spokesman said that despite its lower bid relative to the competition, there was "no compromise on the project's safety".
"With more than 50 years' track record in the industry, we are committed to ensuring project quality and workplace safety for projects that we undertake. For every tender bid that we participate in, we will evaluate and submit a bid which we feel is competitive and offers us reasonable profit margins."
Q Why was OKP, which was given 25 demerit points by the Ministry of Manpower (MOM) and blacklisted for three months earlier this year, allowed to work on a government project?
A In September 2015, OKP was involved in an incident in which one worker was killed and four injured after they fell more than 6m from a dislodged platform. The firm was found to have breached the Workplace Safety and Health Act for failing to ensure the working platform erected was safe for use.
According to the MOM website, 25 demerit points are issued to contractors for an accident that leads to death of one person. The points were given this January after the firm was prosecuted in court.
The Straits Times understands that when OKP was awarded the tender, its involvement in the 2015 fatal incident was still being investigated. OKP and one of its site supervisors were convicted of safety breaches only last Tuesday.
Firms that accumulate 25 points will be blacklisted for three months, which bars the contractor from bringing in foreign workers as all work passes will be rejected by MOM during the blacklist period.
They will still be allowed to renew passes for existing workers.
But Lian Beng construction manager Shie Chee Hwa said being on the MOM blacklist has the effect of limiting the firms' ability to tender for new projects. He said: "They will face more targeted and unannounced spot checks for their existing projects too, which can be several times in a month."
But he added that firms can still bid for public sector projects with their existing workforce, though they would have the spectre of the blacklist hanging over them.
Q Why did the corbels holding up the rest of the structure give way?
A The use of corbels in building elevated roads is a standard practice here and around the world, said Mr Chong Kee Sen, former president of the Institution of Engineers, Singapore.
Corbels are support structures designed to hold only a temporary load at the early construction stage, sharing the load with the rest of the scaffolding. When the concrete in the rest of the structure has set, it becomes self-supporting and most of the load is lifted from the corbels, he said. "During construction, corbels are designed to factor in the amount of load that engineers foresee it will carry during this phase, with around 10 per cent tolerance for the typical load it is expected to take."
Foreseeable activities include the weight of the concrete as well as all additional manpower and equipment needed on top of the structure. The task of calculating the load factors falls on the designers or engineers, which in this case will refer to CPG Consultants.
Mr Chong said corbels can fail in scenarios such as ground movements, overloading or design flaws, though he warned against jumping to conclusions before the investigations are complete.
Q What are the measures in place to prevent workplace deaths?
A While there have been 21 workplace deaths this year, only four occurred in the construction sector. There were 66 workplace accidents last year.
MOM conducts more than 6,000 worksite inspections every year, with some firms selected more than others, its spokesman said.
Those found with safety breaches will be taken to task, as "employers bear primary responsibility for managing risks at work and have to take full ownership of the safety and health matters of their employees".
In OKP's case, MOM officers had stepped up inspections on OKP's worksites after the 2015 accident.
Said the spokesman: "Our officers identified minor WSH (workplace safety and health) infractions on OKP's worksites, and have worked with OKP to rectify them immediately."
The last time MOM inspected OKP's worksite at the flyover viaduct was on April 3 - the day before it was removed from the blacklist, he revealed. At the time, the beams and deck slabs had not been installed at the site where the accident occurred. No infringements were found, said the spokesman.
Q Why did LTA stop work at all its worksites for half a day, and what was done during this time?
A All public road and rail worksites under LTA had to observe a "safety time-out" on Friday after the accident, according to its statement.
The Straits Times understands that the time-out ended around 1pm after all contractors carried out a voluntary review of their safety practices.
The Workplace Safety and Health Council has led several planned safety time-outs after a spate of accidents or dangerous occurrences. A time-out differs from a stop-work order, which only MOM can issue and was meted out on the Upper Changi Road East site on Friday.
Related
LTA Media Statement:
- Worksite Accident -14 Jul 2017
- Media Update at 1900hrs on Worksite Accident at Slip Road from Upper Changi Road East to PIE (Changi) -14 Jul 2017
- Media Update at 1030hrs on Worksite Accident at Slip Road from Upper Changi Road East to PIE (Changi) -15 Jul 2017
- Media Update at 1100hrs on Worksite Accident at Slip Road from Upper Changi Road East to PIE (Changi) -16 Jul 2017
LTA Media Statement:
- Worksite Accident -14 Jul 2017
- Media Update at 1900hrs on Worksite Accident at Slip Road from Upper Changi Road East to PIE (Changi) -14 Jul 2017
- Media Update at 1030hrs on Worksite Accident at Slip Road from Upper Changi Road East to PIE (Changi) -15 Jul 2017
- Media Update at 1100hrs on Worksite Accident at Slip Road from Upper Changi Road East to PIE (Changi) -16 Jul 2017