SINGAPORE — Construction company Or Kim Peow Contractors (OKP), its project director Yee Chee Keong and project engineer Wong Kiew Hai were on Friday (22 January) found guilty of their respective charges relating to the collapse of an expressway viaduct near Upper Changi Road in 2017 that claimed the life of one worker and injured 10 others.
After a 60-day trial, OKP was found guilty of failing in its duty to take, so far as was reasonably practicable, measures that were necessary to ensure the safety of its workers.
Meanwhile, Yee, 51, and Wong, 32, were each found guilty of recklessly endangering the safety of workers by failing to call for the stop to all works when they discovered cracks on temporary corbels, or support structures, of a deck slab as it was being cast.
The duo were also found guilty of intentionally obstructing the course of justice by deleting a WhatsApp conversation between them on the night of the collapse containing photographs and information potentially relevant to the investigations.
Sentencing will be at a later date.
About the case
Part of the 1.8km-long viaduct, which stretched from Tampines Expressway to the Pan-Island Expressway and Upper Changi Road East, collapsed at about 3.30am on 14 July 2017.
OKP had clinched the contract to build the viaduct from the Land Transport Authority (LTA) on 23 November 2015.
Eleven workers who were at the top of that section of the viaduct working on the casting of the deck slab plunged down amidst metal rebars, concrete and machinery.
Chen Yinchuan, a 31-year old Chinese national, died while the 10 other workers suffered injuries ranging from abrasions and lacerations to fractures of their limbs, pelvis and spine.
The technical cause of the collapse was the failure of the corbels supporting the span of the viaduct.
But prosecutors noted that there were multiple red flags and warning signs as far as two weeks prior to the collapse, as well as on the night before the collapse, which would have indicated a risk of corbel under-design and inadequate load-carrying capacity.
Crucially, there were repeated instances of cracks on the corbels of the viaduct’s superstructure, they contended.
In May 2018, OKP, its group managing director Or Toh Wat, along with Yee, Wong, and two others – consultants Robert Arianto Tjandra and Leong Sow Hon – were charged for respective breaches under the Workplace Safety and Health Act and the Building Control Act.
Leong, an LTA-appointed accredited checker, was jailed for six months in July 2019 for failing to inspect the structural design of the viaduct. While the segment of the viaduct that gave way was not under Leong’s purview, investigations found that the engineer had not checked on 10 permanent corbels that had been assigned to him.
His failure to evaluate, analyse and review the structural design of the permanent corbels would have led to five corbels collapsing at the construction stage and, had the viaduct been opened to the public, three more would have collapsed.
Tjandra, was jailed for 86 weeks, or about one year and eight months, in December 2019. He was also fined $10,000.
The engineer was working for subcontractor CPG Consultants when he approved the design for the project and supervised construction works. But he failed to ensure that building works for the project were designed in accordance with the law, and also authorised building works without approval.
Tjandra knew his team of engineers were inexperienced in designing bridges, but he failed to give them guidance or instructions. He also failed to check the design assumptions made for the corbels. And even after he realised the errors in his team’s calculations, he failed to take remedial steps.
Meanwhile, Or was on 31 July given a discharge not amounting to an acquittal for his three charges in relation to the collapse. He was given a conditional warning from the Building and Construction Authority and the Ministry of Manpower.
For its charge, OKP faces a fine of up to $1 million.
For recklessly endangering the safety of workers, Yee and Wong each face up to two years’ jail along with a possible fine of up to $200,000.
The maximum punishment for obstruction of justice is up to seven years’ jail and a fine.
In December 2018, LTA announced that it had appointed another company to finish the viaduct, which is slated for completion in the first half of next year.