A first-class seat on the slower train costs 454.5 yuan and a second-class seat 238.5 yuan.

"During this past winter, the line withstood as many as 52 snowstorms, and all the infrastructure and equipment functioned well," said Liu Qijun, deputy chief engineer of the bureau.

"Through a large number of tests and four months of commercial operation, we have accumulated much experience such as how to avoid being affected by snow and remove ice that covers the tracks."

Liu said the exact dates of schedule changes are based on weather conditions and whether the speed of each schedule will be accelerated depends on "comprehensive assessments".

Railway technicians are busy conducting the final tests to prepare for the higher speeds starting on April 21.

"In the acceleration tests, we started at 220 km per hour and will gradually speed up from that to 240, then 260, 280, 300 and eventually 310," Gao said.

Tests on wireless Internet access and audio and data recorders are also under way, using equipment and software developed by China, said Ji Zhenhong, a technical official of the bureau.

A host of techniques used in the construction, operation and maintenance were acquired from the Qinghai-Tibet Railway, which also faced complicated weather and geological conditions, said Wang Bin, a publicity official from the China Railway Corp.

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