SHIPS and ferries using heavily congested shipping lanes near Ma Wan face a new hazard from May when access will be restricted for two days a week. The measures are being imposed for about a year to allow contractors to fix massive steel decks for the $8.8 billion Kap Shui Mun and Tsing Ma bridge projects. The Marine Department's senior marine officer, John Lambourn, said the Kap Shui Mun channel would be totally closed one day a week from May 27 while deck sections are floated in by barge and hoisted into position. Restrictions in the Ma Wan channel will begin from June 22. Shipping lanes will remain open to all vessels except those being guided by pilot. But ships and ferries will have to take extra care to avoid contractors' boats and barges working in the middle of the channel. 'We don't anticipate too many difficulties, but there will be a bit of disruption, particularly for ships and ferries using the Kap Shui Mun channel because it is the shortest way,' Mr Lambourn said. The Kap Shui Mun channel will be closed because it is too narrow to allow vessels to pass through safely while bridge work is being done. 'There is no space left over,' Mr Lambourn said. He explained that Marine Police and department launches will be at the channel entrance to divert boats. Similar precautions were successfully used last year when the Ma Wan channel was closed for a day to allow builders to install the first suspension cables for the Tsing Ma bridge. The only incident was when a rogue boat ignored warning sirens from police launches and travelled through the channel. Department officials have drawn up a schedule of restrictions, but will meet contractors this week to confirm specific dates. The department hopes to alternate them over the same two days each week, but realises this is almost impossible because the deck lifts are heavily dependent on the contractors' work programme and tides. Restrictions will cover 12 hours but could be shortened, depending on progress. 'Each deck unit has to be lifted 70 metres vertically. The fastest these units can travel is 10 metres per hour, so you are looking at a minimum closure of seven hours without any hitches,' Mr Lambourn said. The department is planning an extensive publicity campaign, including letters to individual shipowners and masters, to make people aware of the restrictions.