Changi viaduct collapse: LTA-appointed checker admits he didn't review structural plans

The PIE viaduct along Upper Changi Road East, collapsed at about 3.30am on 14 July 2017. (PHOTO: SCDF)

*This story was updated at 2.25pm on 24 June 2019

SINGAPORE — An accredited checker (AC) who was working on the viaduct in Changi that collapsed in 2017 admitted on Monday (24 June) that he failed to carry out his duties properly.

Singaporean Leong Sow Hon, 61, an engineer, had failed to evaluate, analyse and review the structural design, and perform original calculations for the structure’s permanent corbels between 18 November 2016 and 13 June 2017. A permanent corbel is a key weight-bearing concrete structure, essential for the support and overall structural stability of the viaduct.

While the corbels that collapsed were not under Leong’s purview, investigations found that eight out of 10 corbels under his watch were inadequately designed and would inevitably have given out at some point.

A separate charge of falsely certifying that he carried out an evaluation, analysis and review of the plans of the building works in accordance with regulations will be taken into consideration for his sentencing.

As an AC appointed by the Land Transport Authority, Leong was required to check structural plans and design calculations of building works by submitting independent calculations and analyses.

Accused lied about calculations

A section of the 1.8km-long PIE viaduct along Upper Changi Road East collapsed at about 3.30am on 14 July 2017. The accident killed one worker, Chinese national Chen Yinchuan, and left 10 others injured.

During Building and Construction Authority’s investigations into the incident, Leong had claimed on 26 July 2017 that he had performed original calculations at the submissions stage. He also claimed to have checked the permanent corbels and found them to be adequate.

Leong was then asked to provide evidence of original calculations but was unable to do so. He admitted on 21 September 2017 that no calculations had been done.

Prosecution seeks jail, defence seeks fine

The prosecution called for a nine-month jail sentence for Leong, noting that there was potential for great harm to have been done due to his negligence.

If things had carried on it would have led to portions of the viaduct collapsing, putting road users at risk, said Deputy Public Prosecutor (DPP) Yang Zi Liang.

According to the prosecution, the AC role was implemented following the collapse of Hotel New World in 1986. An AC was intended as the “final checking mechanism” in the design process of any building structure and to ensure that any flaws in structural plans would be detected.

“The AC is personally responsible for the checking of plans and design calculations. This is regardless of whether he operates individually or within an accredited checking organisation. This duty is non-delegable,” said DPP Yang.

Leong’s lawyer, Tai Chean Ming, sought a fine of $25,000, pointing out that his client was not involved in the section of the viaduct that collapsed.

He also disagreed with the prosecution on the need for deterrence, stating that despite the rise in number of construction site accidents, there was no evidence to show there were more incidents involving ACs.

He added that jail terms were not imposed in the “handful of cases” that involved ACs over the last two or three decades. ACs who were derelict in their duties knew that they faced serious consequences, such as disciplinary proceedings and loss of qualification, said Tai.

“We submit that this alone will deter ACs from taking obligations lightly,” said Tai, who added that “terrorising the profession” would not increase the deterrent effect.

Leong is expected to be sentenced on 5 July. He faces up to two years’ jail or a fine of up to $100,000 for his charge.

Others implicated

Construction firm Or Kim Peow (OKP) Contractors and four other individuals – group managing director Or Toh Wat, employees Yee Chee Keong and Wong Kiew Hai, and consultant Robert Arianto Tjandra – were charged on 30 May last year.

All parties are claiming trial to breaches under the Workplace Safety and Health Act and the Building Control Act and have yet to been dealt with by the court.

Both the firm and Or are accused of failing to take measures to ensure the safety and health of the firm’s employees by failing to adequately assess risk when they became aware of cracks that had formed on the corbels.

They had also allegedly failed to stop all work on the viaduct after discovering fresh cracks had formed on the corbels, which led to the fatal incident.

OKP and Or were also both charged for allegedly carrying out unauthorised strengthening works on a corbel without the approval of the Commissioner of Building Control, and for failing to notify the Commissioner of the contravention of a section the Building Control Act.

Yee and Wong were each charged with one count of recklessly committing an act, which endangered the safety of others. They are accused of failing to halt all works on the viaduct section when cracks were discovered in the corbels supporting the section upon which the workers were casting a deck slab.

Both men were also charged with one count of intentionally obstructing the course of justice by deleting a WhatsApp conversation between each other which contained photographs and information potentially relevant to criminal investigations.

Yee also faces one count of permitting unauthorised strengthening works without the approval of the Commissioner of Building Control.

Tjandra faces one count of recklessly committing an act that endangered the safety of others. He allegedly put up structural plans without checking the design assumptions made for the cracked corbels.

He also allegedly did not carry out the necessary remedial works to rectify the inadequate design, even after knowing that the corbels could not support the deck slab while it was being concreted.

Tjandra was also accused of failing to ensure that the building works relating to the permanent corbel structures were designed in accordance with the provisions of the Building Control Act and regulations, and accused of failing to notify the Commissioner of Building Control of the contravention of a section in the act.

He is also accused of authorising strengthening works without approval from the Commissioner of Building Control and of falsely certifying that the structural plans and design calculations were prepared in accordance with the Building Control Act and regulations.

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