It was still dark at 7 am in Sandaoling. The only light came from a bathhouse, the meeting place for the drivers, 300 meters from the tracks. Liang Guoqiang, the head driver, approached a blackboard covered with name tags and began to arrange the day's schedule.

Drivers with blackened faces were each given a white "off-duty" card and headed for the showers, while drivers who had just finished washing got a red "on-duty" card.

"Operating a steam locomotive in the mine is just like driving an open car. Your whole face except your eyes turns black during your 12-hour shift," said Cheng Zhongyun, 55, a driver of one of the locomotives.