SINGAPORE — In a packed courtroom on Thursday (Aug 1), prosecutors laid out the case against three men and a construction firm over the fatal collapse of a section of uncompleted Pan-Island Expressway (PIE) viaduct in July 2017.

They alleged that half an hour before the collapse, which happened along Upper Changi Road East, the main contractor’s project engineer and other employees discovered cracks on two temporary concrete support structures.

Wong Kiew Hai from Or Kim Peow (OKP) Contractors then phoned Yee Chee Keong, the firm’s project director, to tell him about it and also sent him photographs of the cracks.

However, neither man asked for casting works to stop on the deck slab supported by the structures, despite other personnel urging them to do so.

At around 3.30am on July 14, 2017, the two structures — called corbels — gave way.

The collapse resulted in the death of 31-year-old Chinese national Chen Yinchuan. Ten other workers suffered varying degrees of injuries, including spinal and pelvis fractures. They had been working on the slab then.

The prosecution’s case emerged as the trial over the fatal collapse began in the State Courts, before Principal District Judge Ong Hian Sun.

WHAT THE CHARGES ARE

OKP, the main contractor, and the three individuals — including Malaysian national Wong, 31, and Singaporean Yee, 49 — are contesting their various charges.

OKP faces one charge of failing to take necessary measures to ensure their employees' safety and health.

Earlier this week, the company pleaded guilty to carrying out unauthorised strengthening works to a permanent corbel of the structure on July 8, 2017. A second similar charge, for failing to get approval for the strengthening works, was taken into consideration for sentencing.

OKP was fined S$10,000 for that. 

Then on Wednesday, all three charges against its group managing director, 51-year-old Or Toh Wat, were withdrawn after he was given a conditional warning.

One charge against Yee — for permitting the carrying out of said strengthening works — was also withdrawn.

He now faces two charges of recklessly endangering the workers’ safety by failing to call for works to be stopped, and deleting the WhatsApp conversation between Wong and himself containing the photographs. Wong faces two similar charges.

The project’s qualified person Robert Arianto Tjandra, 46, is contesting five charges, including recklessly endangering the safety of those near the viaduct through acts and omissions.

The professional engineer was an employee of CPG Consultants, who were engaged by OKP and the Land Transport Authority (LTA) to design and supervise the building works.

Tjandra, an Indonesian national, is represented by lawyers from Rajah & Tann, led by Senior Counsel Lee Eng Beng.

Lawyers from WongPartnership are defending OKP, led by Senior Counsel Alvin Yeo. 

Wong and Yee are represented by Tan Rajah & Cheah lawyers, led by Senior Counsel Chelva R Rajah.

WHAT ALLEGEDLY HAPPENED

The viaduct, which is about 1.8km long and made up of 50 spans divided into eight flyovers, links the PIE to Tampines Expressway and Upper Changi Road East.

The incident involved the longest span, which measured about 43.5m long.

Deputy Public Prosecutor Kristy Tan told the court that they will call witnesses to testify that on June 16, 2017, a month before the incident, OKP’s employees discovered cracks on one of the corbels that eventually collapsed.

Yee and OKP’s project manager, Mr Andy Chang, were aware of this. OKP then took steps to rectify the problem on the recommendations of OKP’s technical director, Mr Yueng Chun Keung, who gave his testimony on Thursday afternoon and would do so again on Friday.

OKP joined the two plinths — concrete bases to uniformly distribute loads to the underlying structure — in a single piece, but did not tell Tjandra about this.

Two weeks later on June 30, 2017, another project engineer in Yee’s team, Mr Goh Ee Hui, saw cracks on the second corbel.

The prosecution said that Mr Goh immediately reported them to Yee. Mr Yueng then assessed the cracks on-site again and considered them to be structural cracks.

He told Yee to ask Tjandra to check on the adequacy of the design of the crossheads, a concrete structure that supports a viaduct beam.

Tjandra inspected the site on July 3, 2017, before telling the CPG design engineers working under him to check on the adequacy of the crossheads design.

Prosecutors said they will lead evidence from the design engineers that by early July 2017, they had discovered a fatal assumption in the calculation of the corbel widths.

Because of this, the capacity of many of the corbels were inadequate for the loads they were meant to carry. Although Tjandra knew of it, he did not tell OKP of the design errors or redesign the corbels that eventually collapsed, prosecutors added.

Instead, on July 5, 2017, Tjandra sent Yee a revised construction sequence for the deck slab casting works at the section in question.

About five days later, OKP followed his instructions. But prosecutors told the court that their witnesses will testify that Tjandra did not inspect OKP’s actions or tell his resident engineers to do so, only exchanging WhatsApp messages with Yee to check on it.

Tjandra also told OKP to add more reinforcing steel bars to other corbels, which they did.

In the early hours of July 14, 2017, OKP began the works, with Wong among the people present. At about 2.50am, they saw cracks on the sides of the two corbels, which prompted Wong to call Yee and send him photographs.

An LTA site supervisor, among others, urged Wong to stop the works. He did not.

Prosecutors charged that shortly after the collapse at 3.30am, Wong and Yee deleted their WhatsApp conversation to “bury their responsibility”.

Prosecution experts will testify that the corbels failed due to overloading, stemming from design flaws. OKP’s expert witness reviewed CPG’s design and concluded the same thing in his report.

The trial continues on Thursday afternoon, with hearings in this first phase set to go on until Aug 8.