Deep beneath the capital's streets and through the gloom, the muffled sounds made by one per cent of Beijing's huge underground Olympic workforce is distinct. Women in hard hats call out instructions as they uncoil a thick cable and thread it along a widened stretched of the near-finished Line Five, one of the new underground metro tracks being builtfor the 2008 Games. 'The really dangerous and heavy work is over, so there are more women on the site now,' says Kong Baode, the managing director of the Tiantan East Gate Station construction site. Kong can be forgiven for his throwaway sexist remark. Women construction workers wielding pickaxes and jackhammers are two-a-penny above ground. That there are only 600 females among the 60,000 subterranean navvies tunneling away is probably for safety reasons. Besides, there are more pressing concerns, such as getting the track open on time and alleviating Beijing's horrendous and worsening traffic and pollution than fretting over PCism 25 metres below ground. 'We are due to open in July next year, and we'll have a big ceremony. We hope Liu Qi [head of Bocog and Beijing's mayor] will open the line,' adds Kong, who has overseen the building of the Tiantan station and about 2km of Line Five's track. Line Five runs north to south under the city for nearly 28km and is serviced by 22 stations. Kong has been at the Tiantan site since the first turf was cut four years ago, and each day has descended beneath the earth to direct operations. And the engineering graduate from Chengdu University says he will continue to work for the MTR Construction Administration Corporation, a state-owned enterprise, until Beijing has the longest subway system in the world by 2020. Beijing's existing 116km of track carries 1.5 million people a day. This will expand almost fivefold to 562km - 160 more than London, the world's longest metro, which carries 3.5 million people daily. There are four lines in operation in Beijing - two of which began in the late 1960s and were finished in the 1970s. Then, bikes still ruled the roads and no more tracks were opened until the opening of the northern, looping, overground light railway - Line 13 - in 2003, and which has since opened up new suburbs where only a few years ago there were only fields. Ambitious planners from the Beijing Municipal Institute of City Planning and Design say they intend to add one line a year after 2008 - and six underground roads will also be bored into Beijing's dry, fine sandy soil. Before their drawing board dream arrives at that subterranean transportation utopia, five more lines will open ahead of the Olympics - each with a carriage load of responsibility and prestige. The 96km of new line will speed locals and visitors alike between homes, hotels, airport, Olympic stadiums and showcase visitor attractions. More importantly, they will save many thousands of visitors to New China's coming out party from the misery of the capital's maddening gridlock. 'We have to make our metro the biggest in the world, eventually. We have more people than London, and you've seen the traffic,' says Kong. The smell of new cement is overwhelming and the arc lights cast eerie shadows on Line Five as workers complete the finishing touches. The new transport system has drawn upon metros from around the world for inspiration, and the futuristic steel and metallic concourse at Tiantan is reminiscent of London's Westminster Jubilee Line station. 'We visited Britain and America and other countries. But we have added much of our own technology and have a unique air-conditioning system,' says Kong. The trains are being made in Changchun, and the tunneling machines used during the construction were made in Shenzhen. Hong Kong's MTR was also used for inspiration, and the MTR Corporation last month signed a US$91.8 million agreement to operate the near-completed Line Four for 30 years. A clanking, banging, grating sound echoes out of the darkness and reaches the platform of Line Five, and Kong explains that archaeologists and geologists didn't find anything of historical value when they made their excavations. 'In other areas, historical relics were found,' says Kong, without going into detail. However, it is well documented that an underground city was built on the orders of Mao Zedong from 1969 till 1979 to house millions of people in the event of a nuclear or chemical attack. Beijing's 21st century metro planners were told they had to tunnel around the vast network that stretches to the Western Hills, and that boasts clinics, shops, theatres and schools. On our ascent, Kong points out two pairs of thick steel doors that are sealed from the inside to close off the outside world. 'All the stations have them,' he says. Are they to prevent fire or flood? 'No, they are in case of invasion in time of war. People can come here and protect themselves,' he says.