The construction worker who died when a massive tree toppled on him had been told to clear only undergrowth and saplings, his employer said on Wednesday.
Meng Guan Landscape & Construction said Mr Jayaraman Gunasekaran was not supposed to be felling large specimens like the 10m-tall Albizia that crushed him on Sunday.
It added that the 36-year-old Indian national, who had been working for the firm for many years, may have been clearing bushes nearby when his excavator accidentally damaged the tree's roots. This could have toppled the Albizia, a species known to be especially prone to falling during storms. However, the company's account contradicts that of workers who said he had been trying to fell the 1.5m-thick tree by loosening the soil at its base.
Mr Jayaraman - who had a wife and two young daughters back in Tamil Nadu - was helping to clear forest on Thomson Road, where the Caldecott MRT interchange is due to be built.
The Manpower Ministry (MOM) halted work at the site and told the main contractor, Samsung C&T, to "review its risk assessments and safe work procedures". Only if these are found to be satisfactory will work be allowed to resume. Landscaping companies told The Straits Times that excavators are sometimes used to fell trees by loosening the soil, but the method can be risky.
They said a safer technique is to cut away the branches and trunk bit by bit from the top. The stump is then dug up after the rest of the tree is removed with the help of a lorry crane.
But this may not be practical in dense forest where a crane cannot be used, said Tan Huan Arboriculture Services manager Andy Tan.
"One way is to see where the tree is leaning towards," added the 32-year-old. "If it leans to the opposite side (of the excavator), it should be no problem."
However, Mr Tan said it is still important to get a qualified tree specialist to assess the risk first.
Goodview Gardening and Landscape Construction owner Palanichamy Mariyappan, 49, told The Straits Times: "You must check how steady the tree is. Some trees can collapse at any time."
Guidelines on landscape and horticulture management, published by the Workplace Safety and Health Council in 2008, refer to the use of excavators for removing stumps, but not entire trees.
Samsung C&T declined to disclose further details. It referred all queries to the Land Transport Authority, which said it could not comment due to ongoing investigations by the MOM.
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