A SECOND error in calculating the width of a wall on the Kwun Lung Lau Estate in Kennedy Town contributed to the failure to take precautions which could have prevented its collapse, a Coroner's jury heard yesterday. The mistake was made by a government engineer who 'assumed' that the wall, which later gave way during a landslide killing five people, was of a safe thickness. Nigel Kat, representing the Hong Kong Housing Society who own the estate, said: 'The assumption made by the engineer was incorrect. The wall was not 2.4 metres thick, nor did it have a vertical back.' He added: 'As a result of that study, nothing was drawn to the attention of the Housing Society to lead them to think the wall might be inadequate.' A representative from the Geotechnical Office, Chief Engineer Chan Yung-cheung, said the engineer's mistake could be seen with hindsight. He added that in 1987, when the assessment was made, there was no need to draw anything to the attention of the property owners. The engineer, who was not named, had read a building report which wrongly stated that the wall was four metres thick. But he did not rely on this and made an alternative estimate that the wall was at least 2.4 metres thick, the inquest heard. 'It was concluded that no further study was required under the circumstances,' Mr Chan said. The real width of the wall is said to have been only 75 centimetres. The engineer was from what was then called the Geotechnical Control Office. Mr Chan said the aim of the inspection was to see whether a further detailed study was necessary. He said that the engineer was making a 'conservative estimate' when he estimated the wall's thickness to be 2.4 metres. Mr Kat said the engineer did measure the sides of the wall to help him judge the width. Mr Chan pointed out that the engineer would not have been able to completely ignore the erroneous building report. Mr Chan explained the circumstances in which the engineer would have made the assessment. He said: 'This is a chance for the engineer to make a judgment. To assist his judgment he can make simple calculations. He can look at other drawings. On this occasion he had read the site plan. But to satisfy himself he made an alternative set of calculations to see what the effect would be if the wall was thinner.' The jury is expected to return a verdict today.
