THE operator of a building-site lift which plunged 17 storeys, killing 12 passengers, yesterday told a court he was afraid to stop overcrowding because workers threatened him if they were asked to get out. Yau Siu-Hoi, 55, said that he was told the workers' lift was not meant to have more than eight people aboard at one time. But when Yau, 55, was asked how he usually responded when extra passengers squeezed into the lift, he replied: 'I would make the lift go up as usual.' He told the High Court that his early attempts to limit the number of passengers had simply met with abuse. 'If I told the other people to get out, they would use foul language at me,' he said. 'What could I do? The boss was not there. They threatened to assault me.' Yau was not operating the building site lift on June 2, 1993, when after a click, it suddenly plummeted to the third floor where it smashed on to the podium. All 12 passengers were killed. The case is Hong Kong's first corporate manslaughter trial. In the dock are the site safety supervisor Tam Ping-cheong, technicians Kwong Tim-yau and Hui King-leung and assistant engineer Wong Hon-sang. Wong was employed by Ajax Engineers and Surveyors Ltd. The four men and Ajax are charged with manslaughter. All have pleaded not guilty. The company is accused of issuing a safety certificate for the lift signed by an employee who had not inspected it. The check was alleged to have been carried out by an assistant engineer who had not attended a training course, had no qualifications and had learned how to inspect machines in two weeks. Earlier, the court was told the main cause of the accident had been the condition of the teeth on the pinion connecting the lift to a rack running up the side of the building. The jury heard that only 80 per cent of the pinion teeth's width had been in contact with the rack. The trial, before Mr Justice Duffy, continues.