MARINE Department officers cannot stop vessels passing underneath Tsing Yi Bridge even if it is apparent they may hit the structure, it emerged yesterday. Legislators have demanded the Marine Department be given more power to manage harbour traffic, following Monday's accident in which the boom of a barge hit Tsing Yi South Bridge, rupturing a gas pipe. Utility companies have made plans to move pipelines because of the frequency with which tall vessels have collided with the bridge, damaging power cables and pipes. But legislators attributed the accident to a loophole in the Shipping and Port Control Ordinance which means marine officers are not empowered to take action unless there is an accident. United Democrat legislators Mr Lee Wing-tat and Mr Albert Chan Wai-yip held an hour-long discussion with the Director of Marine, Mr Allan Pyrke, about the department's initial investigation into the accident. Mr Lee said: ''We were shocked to learn from the director that even if there were marine officers at the scene and even if it was clear that the barge was taller than 17 metres, the officers could not stop it from travelling under Tsing Yi Bridge. ''They can only act when an accident has taken place. It is a laughable ordinance.'' Mr Chan said they planned to meet the Secretary for Economic Services, Mr Gordon Siu Kwing-chue, next week to press for immediate action and hoped the review could be completed in the current Legco session. Mr Pyrke said proposals to review the law had been put forward after two collisions at the bridge last year, but it took time to go through the legislation procedure. He said a report on the cause of the accident could not be made public if the barge operator was not prosecuted. Some shipping companies are concerned about a rise in costs if big barges are banned from Rambler Channel, which passes under Tsing Yi Bridge. They said barges with derricks taller than 17 metres had become more common in Hongkong with the growth of cargo transport. Yesterday morning, repair crews returned to Tsing Yi South Bridge to inspect the pipeline damaged in the accident in which an A-frame holding the barge derrick in a vertical position smashed through several strips of protective metal and ruptured a 30-centimetre Towngas pipe. Utility companies have pledged to move their pipelines away from the south bridge after repeated damage from barges. The gas and water pipes and telephone and electricity cables which hang along the sides of the bridge will be replaced by lines to be built in service bays underneath a new bridge to the south. Highway Department officials said yesterday that the new Tsing Yi duplicate south bridge was designed to accommodate utility links between Tsing Yi and Kwai Chung in a more concealed way. It would be similar to the Tsing Tsuen or Tsing Yi North Bridge which was designed in 1981 and completed in 1987 with cables embedded in concrete bays. Construction for the $815 million duplicate bridge is due to start this year. The existing Tsing Yi South Bridge was completed in 1974 and has electricity cables, optic fibres and a 25-centimetre Towngas pipe hanging along its sides. A Towngas spokesman said the gas pipe had been damaged several times before Monday. He said automatic valves had been added to cut the gas supply to the pipe following the leakages caused by the previous accidents.