Construction will start today on Xi'an's first subway line amid public concern about possible damage to the ancient city's cultural heritage.

The 26.4 kilometre-long metro line, which will run from north to south, will pass under a number of ancient buildings, such as the Bell Tower (built in 1384) and the ancient city wall (built in 1368).

More than 23.5 kilometres of the line is underground, with the rest above ground.

Xi'an is a world-famous city, which has served as the capital for 13 dynasties, and contains a large number of ancient cultural sites both above and below ground.

"One of the most important things is to guarantee the metro line won't harm our cultural heritage," said Hou Rongjie, director of Xi'an Subway Construction Office.

According to Hou, the metro will go around the Bell Tower, which stands in the centre of the city, to avoid undermining it.

The metro, which will be built more than 20 metres underground. will use a special design to reduce vibration and noise, said Yuan Wencheng, a professor at Xi'an Construction Science University.

According to Xi'an Metro Construction Office, the city plans to have two metro lines line 1 from east to west and line 2 from north to south.

Work on line 2 will be completed in 2011 and will cost 17.9 billion yuan (US$2.24 billion).

"When it is completed, the train will take only 39 minutes to travel from north to south, saving more than one hour on the current journey time. It will greatly decrease traffic jams in rush hours," said Qiao Zhen, in charge of urban construction in Xi'an.

The city is the first in western China to build a metro line. Only six cities, Beijing, Shanghai, Tianjin, Guangzhou, Nanjing and Shenzhen, all in eastern China, have metro systems at present.

(Xinhua News Agency September 29, 2006)