By Shirong Chen
BBC News, China analyst
China is investing billions of dollars into its rail network
China has announced plans to build 42 new high-speed railway lines over the next three years.
In a breakthrough, China has developed trains that can run on both high-speed and normal lines, said railway official Zhang Shuguang.
A 500km/h train will be tested by the end of next year, Mr Zhang said.
China will have added 13,000km of high-speed lines by 2012, shortening journey times considerably for the expected seven billion annual passengers.
Journey times from the capital Beijing to most provincial capitals will be as short as seven hours, said Mr Zhang, the Chief Engineer of the Chinese Academy of Railway Sciences.
He revealed the plans at a science and technology conference in the city of Chongqing.
Four north-south and four east-west links are taking shape across China's vast geography.
Construction on the Beijing-Shanghai line is in its second year. The section from Wuhan in central China to Guangzhou in the south will be completed in December, shortening the journey time to four hours.
Mr Zhang said China's breakthrough in developing trains that can run at high speeds on both normal tracks and specially-laid high-speed lines will greatly enhance the network's efficiency.
Overcrowding is often a problem on Chinese trains, especially during peak periods such as the National Day holidays and the Chinese New Year.
The country is investing heavily to expand its railway system by 2020.
When the high-speed network is completed in 2012, it will be able to carry more than seven billion passengers annually, Mr Zhang said.
By then, the existing system will have been expanded by about 20,000km to more than 110,000km.