MECHANICAL problems have been ruled out as a cause of the Wan Chai bus crash, operator Citybus claimed yesterday. Initial investigations into Friday's crash, which killed three people, found the double-decker was in perfect operational condition, the company said. While human error now seems the most likely cause, police have yet to interview the driver or reveal breathalyser results taken after the crash on the Tonnochy Road flyover. Last night six of the passengers from the Route 118 bus were still fighting for their lives at Eastern and Queen Mary hospitals, three were in poor condition and another 24 were stable or satisfactory. Driver Shum Wing-yiu, 31, remained in satisfactory condition at Queen Mary but police said he was 'too traumatised' to talk. Neither the police nor the Transport Department would confirm a Citybus statement that the Dennis Dragon bus had been cleared by Government inspectors of any mechanical problems, saying no details would be released until the inquiry was completed. A police spokesman said a vehicle examiner from the Transport Department had been seconded to scrutinise the bus. Officers were still taking statements from passengers who were on the Siu Sai Wan to Shamshuipo bus when it skidded and flipped over on the flyover next to the Sun Hung Kai Centre. Witnesses described how the roof was ripped off, flinging three passengers to the road below - where one of them died - as the bus took a 90-degree bend, apparently at a speed of up to 80 km/h. The speed limit on the flyover is 50 km/h. The fatal crash occurred during the driver's first trip that day. According to Citybus, he had had a full day's rest the previous day. The driver was on his assigned route and was on schedule. Chief Secretary for Administration Anson Chan Fang On-sang visited injured passengers at Queen Mary Hospital yesterday amid criticism that neither she nor Tung Chee-hwa had visited the crash site or the victims earlier. 'We are, of course, very concerned at the reasons for this serious accident. The police and the Transport Department will be carrying out separate investigations,' she said. Director of Highways Kenneth Leung Kwok-sun told a radio phone-in programme that the design of the 10-year-old flyover met safety standards. He said anti-skidding devices on the road would not have helped to prevent the accident. 'What matters most is driving one's vehicle within the speed limits,' he said. 'No roads would be safe if you drive at 100 km/h hour on a road which is designed for 50 km/h.' ' He admitted there was little the Government could do to improve the flyover itself, other than demolishing it, as it was situated at a right angle between Gloucester Road and Tonnochy Road. But he said the Government would consider installing a warning sign near the bend on the flyover to remind drivers to slow down. Citybus continued to offer condolences and said compensation claims by victims and relatives would be passed on to their insurance company for processing. The firm says it will in the meantime offer appropriate assistance to the families of those who died.