Imagine, one day,getting out of bed in Beijing and being at your office in Shanghai in only a couple of hours,and then,after a full day of work,going back home to Beijing and having dinner there. Sounds unusual,doesn't it? But it's not that unrealistic,with the development of China's high-speed railway system.And that's not all.China has an even greater high-speed railway plan -- to connect the country with Southeast Asia,and eventually Eastern Europe. China is negotiating to extend its own high-speed railway network to up to 17 countries in 10 to 15 years,eventually reaching London and Singapore. China has proposed three such projects.The first would possibly connect Kunming with Singapore via Vietnam and Malaysia.Another could start in Urumqi and go through Kazakhstan and Uzbekistan,and possibly to Germany.The third would start in the northeast and go north through Russia and then into Western Europe. If China's plan for the high-speed railway goes forward,people could zip over from London to Beijing in under two days. The new system would still follow China's high-speed railway standard.And the trains would be able to go 346 kilometers an hour. China's bullet train ,the one connecting Wuhan to Guangzhou,already has the World's fastest average speed.It covers 1,069 kilometers in about three hours. Of course,there are some technical challenges to overcome.There are so many issues that need to be settled,such as safety,rail gauge ,maintenance of railway tracks.So,it's important to pay attention to every detail. But the key issue is really money.China is already spending hundreds of billions of yuan on domestic railway expansion. China prefers that the other countries pay in natural resources rather than with capital investment.Resources from those countries could stream into China to sustain development. It'll be a win-win project. For other countries,the railway network will definitely create more opportunities for business,tourism and so on,not to mention the better communication among those countries. For China,such a project would not only connect it with the rest of Asia and bring some much-needed resources,but would also help develop China's far west.We foresee that in the coming decades,millions of people will migrate to the western regions,where the land is empty and resources unused.With high-speed trains,people will set up factories and business centers in the west once and for all.And they'll trade with Central Asian and Eastern European countries. According to the passage,the greatest challenge to the new high-speed railway plan is   _  .
technical issues safety of the system financial problems maintenance of railway tracks