The city's future noise barriers will be more pleasing to the eye and green-minded, the Highways Department said at the launch of its first design competition for the structures yesterday. The department will spend HK$200 billion on building roads and railways in the next 10 years, with some of the money going to noise reduction. 'There will be many noise barriers and noise enclosures, depending on the outcome of the environmental impact assessments,' Director of Highways Wai Chi-sing said. 'Citizens are more concerned now about the appearance of the noise barriers.' The public can expect more environmentally friendly sound walls, according to Highways Department chief engineer Chow Chun-wah. Barriers were previously made from transparent panels or opaque insulating boards, Mr Chow said, describing the effect as 'artificial'. The new versions would be closer to nature, he said. Some future sound barriers could consist of 'growing media' that could support plant life, he said. Some walls would be made of stone wool, porous man-made fibres known to trap water and block sound effectively. Tightly spaced roads were not expected to benefit, as such structures required 'sufficient space'. Obstruction to commercial activity and maintenance were the other main concerns, Mr Chow said, explaining that plants had to be constantly pruned and fertilised. He hoped that green designs would be used on 20 per cent to 50 per cent of all soundproofed road sections, although he stressed that reducing the overall use of noise barriers remained a priority. Large projects that the Highways Department would take on in the next financial year included finishing off the Tuen Mun Road improvement project, the widening of the Tolo Highway, building the Central-Wan Chai bypass and starting the West Island railway line, Mr Wai said. The noise barrier design competition, also backed by the Environmental Protection Department and the Hong Kong Institute of Landscape Architects, will be open to design professionals and the public.