SINGAPORE - Unauthorised work to strengthen surrounding corbels, failure to flag flaws and cracks in the viaduct's design and structure despite being aware of them, and deleting potentially incriminating Whatsapp messages.

These were just some of the allegations made in court on Wednesday (May 05) against the group involved in the collapse of the Pan-Island Expressway (PIE) viaduct.

The five individuals and main contractor for the project, Or Kim Peow Contractors, were charged in court under the Building Control Act and the Workplace Safety and Health Act for their roles in the incident that happened on July 14 last year (2017) in Upper Changi.

The Acts come under the Building and Construction Authority (BCA) and the Ministry of Manpower (MOM), respectively.

The incident resulted in the death of Chinese worker Chen Yinchuan, 31, while 10 others were hurt - two seriously.

Court documents alleged that the local construction firm and its group managing director Or Toh Wat, 50, were aware of the cracks in the corbels - support structures - of piers 40 and 41 of the viaduct, but had failed to do proper risk assessments of the affected corbels and take measures to ensure safety and health of employees.

Or and the firm were also charged with conducting unauthorised strengthening works to surrounding corbels six days prior to the collapse.

The company was also accused of failing to stop works from taking place on the affected corbels despite discovering fresh cracks on the structures that supported the viaduct section.

Investigations revealed a 40m section of the viaduct, between piers 40 and 41, had given way, with preliminary findings pointing to corbels breaking under the weight of wet concrete.

Post-incident checks also revealed cracks at 11 other locations along the viaduct.

Project engineer Wong Kiew Hai, 30, and project director Allen Yee, 48, both from Or Kim Peow Contractors, were also charged with various offences under the Acts.

They were both accused of obstructing the course of justice by deleting a Whatsapp conversation they shared on the day of the incident. The conversation allegedly contained photographs and information potentially relevant to criminal investigations.

They could face a jail term of up to seven years or a fine, or a combination of both for the offence.

Wong and Yee were also charged with endangering the safety of workers by allegedly failing to stop works on the viaduct section after discovering cracks on the affected corbels. These corbels of piers 40 and 41 were supporting the section on which employees were working on.

The qualified person from subcontractor CPG Consultants, Robert Arianto Tjandra, 45, who approved the design and supervision of the construction works for the project, face five charges under both Acts - the highest among those charged.

Arianto Tjandra was accused of endangering the safety of others by putting up structural plans without checking on the design assumptions made for the corbels between the affected piers. It is also alleged that he knew the said corbels lacked the capacity to support construction works and live loads when the deck slab was being concreted, but he failed to carry out necessary remedial works.

He was also accused of falsely certifying that structural plans and design calculations of the viaduct were in line with the Building Control Act and regulations, even though they were not.

The fifth man to be charged was Calibre Consulting Singapore executive Leong Sow Hon, 60, who was the accredited checker for the project.

Leong, whose role involved double-checking Arianto Tjandra's load calculations, was accused of falsely certifying that he had carried out an evaluation, analysis and review of the plans of the building works, when he had not done the checks.

He is also accused of not carrying out his responsibilities as he had allegedly failed to evaluate, analyse and review the structural design in the plans and perform original calculations for the permanent corbels that are key structural elements of the viaduct.

Sentences for the five and Or Kim Peow Contractorsrange from jail terms and fines of up to $200,000.

The case has been adjourned for July 11. District Judge Christopher Goh set a bail of $20,000 for Yee and Wong, and $15,000 for Arianto Tjandra.