Workers construct the Shilin tunnel of the Yungui railway, a railway linking Kunming of Yunnan Province and Nanning of Guangxi Zhuang Autonomous Region, in Shilin County, Southwest China's Yunnan Province, August 11, 2013. The underway Shilin tunnel, designed to have a length of 18,208 meters, is expected to be finished by the end of 2013. (Xinhua/He Junchang)

Workers construct the Shilin tunnel of the Yungui railway, a railway linking Kunming of Yunnan Province and Nanning of Guangxi Zhuang Autonomous Region, in Shilin County, Southwest China's Yunnan Province, August 11, 2013. The underway Shilin tunnel, designed to have a length of 18,208 meters, is expected to be finished by the end of 2013. (Xinhua/He Junchang)

Workers construct the Shilin tunnel of the Yungui railway, a railway linking Kunming of Yunnan Province and Nanning of Guangxi Zhuang Autonomous Region, in Shilin County, Southwest China's Yunnan Province, August 11, 2013. The underway Shilin tunnel, designed to have a length of 18,208 meters, is expected to be finished by the end of 2013. (Xinhua/He Junchang)

Workers construct the Shilin tunnel of the Yungui railway, a railway linking Kunming of Yunnan Province and Nanning of Guangxi Zhuang Autonomous Region, in Shilin County, Southwest China's Yunnan Province, August 11, 2013. The underway Shilin tunnel, designed to have a length of 18,208 meters, is expected to be finished by the end of 2013. (Xinhua/He Junchang)

Workers construct the Shilin tunnel of the Yungui railway, a railway linking Kunming of Yunnan Province and Nanning of Guangxi Zhuang Autonomous Region, in Shilin County, Southwest China's Yunnan Province, August 11, 2013. The underway Shilin tunnel, designed to have a length of 18,208 meters, is expected to be finished by the end of 2013. (Xinhua/He Junchang)

Workers construct the Shilin tunnel of the Yungui railway, a railway linking Kunming of Yunnan Province and Nanning of Guangxi Zhuang Autonomous Region, in Shilin County, Southwest China's Yunnan Province, August 11, 2013. The underway Shilin tunnel, designed to have a length of 18,208 meters, is expected to be finished by the end of 2013. (Xinhua/He Junchang)