China's railway authorities Monday started tests for the coming sixth speed boost.

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An official with China's Ministry of Railways said passenger trains with a speed of 200 kilometers and above per hour will be tested for several days on the Beijing-Shanghai and Beijing-Guangzhou railways.

China has been raising train speed limits since 1997, when most were running at a mere 60 kilometers per hour. The new speed boost is scheduled for April 18.

After the speed boost, trains will run at speeds of up to 200 kilometers per hour on the Beijing-Harbin, Beijing-Shanghai and Beijing-Guangzhou railways. In some sections the speed can be raised to 250 kilometers per hour, the international railway speed upper limit.

The coming speed boost will increase the railway system's passenger handling capacity by 18 percent, and its cargo capacity by 12 percent, according to the ministry.

Insiders say a speed of 200 kilometers per hour demands much higher safety standards and hence more work on upgrading trains and tracks.

Railway safety drew public attention after hurricane-force winds derailed 11 carriages of a train in northwest China's Xinjiang Uygur Autonomous Region on February 28, killing three and injuring 34.

Experts with the ministry say trains running at high speed are more likely to be overturned by strong winds.

The ministry has asked a research center to develop a wind warning system.

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