The Hong Kong section of the new cross-border express train will be the most expensive high-speed railway in the world per kilometre - even at current estimates, which the government says will be exceeded. Based on the original estimate of HK$39.5 billion, the 26 kilometre Guangzhou-Shenzhen-Hong Kong express link will cost HK$1.52 billion, or US$190 million, per kilometre. That is by far the most expensive of 15 high-speed links recently built or under construction around the world, including the 1,318 kilometre Beijing-Shanghai link and the Channel Tunnel rail link between Britain and France. And the cost is set to rise further. The government is preparing new estimates and officials in the know say it is struggling to keep the cost below HK$50 billion. Engineers say the main reason for the high cost is that most of the link - including a 140,000 square metre terminus in West Kowloon - is being built underground. While details have not been made public, an MTR presentation document, circulated among some engineers, shows a state-of-the-art terminus, with three levels below ground, which include two mezzanine floors of car parks, and 15 platforms. Construction will involve excavation of 4.5 million cubic metres of soil and use about one million cubic metres of concrete. 'Two IFC has a total floor area of 185,000 square metres, with a height of 405 metres. Assuming average floor height of four metres, the total volume of IFC 2 is about 740,000 cubic metres,' veteran engineer Albert Lai Kwong-tat said. 'Hence, concrete poured for the station of one million cubic metres is equivalent to 1.35 times the size of IFC 2. The excavation of 4.5 million cubic metres is equivalent to six times IFC 2.' The 26 kilometre link will run through twin tunnels and go through three hills - Golden Hill, Tai Mo Shan and Kai Kung Leng - which is another reason for the high price. By comparison the 345 kilometre high-speed rail line in Taiwan, completed in 2007, cost US$44.71 million per kilometre and the 1,318 kilometre Beijing-Shanghai link just US$24.4 million per kilometre. The 109 kilometre Channel Tunnel cost US$85 million per kilometre. And the 425 kilometre Rhine-Rhone TGV project in France, to be completed in 2011, is estimated to cost around US$7.9 million per kilometre. Engineer and Town Planning Board vice-chairman Greg Wong Chak-yan said he believed the underground terminus would account for more than half the cost of the link. Building underground was several times more expensive than building them above ground, but 'there is no choice', he said. 'The terminus has to be placed underground, given it is in West Kowloon. How would those who live in the luxurious apartments above the site react if it was not underground? How would the arts community react if it was above ground and affected the West Kowloon Cultural District?' There was also no alternative to a tunnel for the track, Wong said. 'There are just too many homes that would have to be demolished if it was not underground.' Engineer Lai believes the government has chosen the wrong site for the terminus. 'It is just too difficult and expensive. To dig so deep also means passengers will have to walk a long way to transfer to other local transport,' he said. Undersecretary for Transport and Housing Yau Shing-mu said the link was costly because the whole thing would be built underground due to environmental and conservation concerns. He said the government was trying to push down the cost but prices for construction materials had risen 50 per cent in the past year. Economists, meanwhile, said not enough information had been released for them to calculate how much a ticket on the express to Guangzhou might cost, or what the ticket price would need to be for the project to break even. Law Cheung-kwok, associate director of Chinese University's Aviation Policy and Research Centre, said the government should release more information, especially on the railway's operation cost. 'It is impossible that the government has no idea how much the operating cost will be. They should know it by now and they should let the public know. Otherwise, no one outside the government can make any meaningful estimation of how long it will take to recoup the cost and whether it is cost-efficient,' Law said. Early discussions on the rail link mentioned a much cheaper alternative - using the existing West Rail tracks. But this was ruled out after the Ministry of Railways told Hong Kong that the new national standard for high-speed trains would be up to 3.4 metres wide, while the West Rail platforms can accommodate trains no more than 3.1 metres wide. The link between West Kowloon and the border is expected to be completed in 2015. It will take 14 minutes for passengers to reach Futian in Shenzhen and 48 minutes to Shibi in Panyu . Passengers for Guangzhou's business district will either have to take the existing through train or transfer to the Guangzhou Metro and travel 18 stops. The Transport and Housing Bureau has projected that 99,000 passengers will use the new link daily in 2016. Of those most will stop in Shenzhen and only 11,000 will go beyond Guangzhou. The government has already told the Legislative Council that the construction cost is likely to increase significantly. Secretary for Transport Eva Cheng said last week the original estimate for the link in 2006 had been 'a bit conservative'. Yau, the transport undersecretary, also said last week that the government would not seek to quickly recover the cost, as it aimed to operate a competitive rail link and attract passengers. He said tickets for the express rail would be slightly higher than the current through-train service, which costs HK$190 per trip.