More than 300 million tons of coal were transported on the Datong-Qinhuangdao Railway in 2007, boosting the capacity of the 653-kilometer heavy-duty railway to anew high, the Taiyuan railway bureau said Monday.

This is the third year in a row in which the railway has increased its cargo volume by 50 millions a year, the bureau said.

The railway linking coal-producing Datong in north China's Shanxi Province and Qinhuangdao port in Hebei Province is playing a pivotal role in meeting the electricity demand in China's economically booming southern provinces.

Running on the track is world's most powerful electric locomotive, capable of pulling a fully-loaded train with a total mass of 20,000 tons, officials with the bureau said.

The railway carried 150 million tons of coal in 2004, the first year of its operation. The track has a yearly designed capability of 100 million tons.

Shanxi's out-of-province sale and export of coal account for 70percent and 50 percent of the country's total. Most of the coal transportation is carried by train.

Figures from the Ministry of Communications show that one out of every 16 tons of coal mined in China is transported by the Datong-Qinhuangdao railway.

The railway links 178 coal transmission lines, 165 coal stations, and is responsible for transporting coal for the country's six power grids, 380 power plants and more than 6,000 factories and enterprises.