The new rail line, passing through Tonghai and Jianshui, is about 30 km (19 mi) west of the old metre-gauge railway (which runs via Yiliang and Kaiyuan).

[8] Construction began on December 15, 2005, and was completed in mid-August 2012[9] and the line opened to commercial service on February 23, 2013.

[10] The Mengzi–Hekou rail line runs 141 km (88 mi) from Mengzi City in southern Yunnan to the Hekou Yao Autonomous County on the border with Vietnam.

[12][13][14][15] Regular passenger service operates between Hekou North and Kunming, with some trains continuing to Dali.

The 7,414 metre-long tunnel is located in Yaoshan Township (瑶山乡) of Hekou County.