Workers on the Tsing Ma Bridge have been told to step up patrols to prevent suicidal people from leaping to their deaths, transport chief Sarah Liao Sau-tung said yesterday. Four people have died leaping from Hong Kong's largest bridge, which opened in 1997, all in the past two years. In a Legco meeting, lawmaker Choy So-yuk asked whether the government planned to take measures such as installing safety nets under the bridge. In a written reply, Dr Liao said that safety nets could not be used because they would affect the bridge's stability in gusty winds and hamper regular inspection and repair work. 'To stop people from jumping off the bridge, the Tsing Ma Management Company Limited has already strengthened its monitoring work,' she said. The number of patrols will be increased and employees have been reminded to stay on high alert while monitoring the bridge on closed-circuit security cameras. The first suicide on the bridge was on September 2001, when a 22-year-old Pakistani man parked his goods vehicle, climbed onto the rail and jumped. There were no reports of suicide on the bridge last year, but there have been three cases this year. On April 21, a 36-year-old taxi driver died jumping off the bridge. On June 20, Wong Kwok-keung, 47, leapt to his death after leaving a note in his car saying he owed $400,000. Then on July 14, another taxi driver, 51, jumped after leaving a note in his cab saying he was unable to pay his debts.