The construction of a tunnel on the Kunming-Vientiane Railway to link southwest China's Yunnan Province with Laos was completed on Sunday.

The Jingkuan No.2 Tunnel, about 4.6 km long, is located in Jinghong City of Yunnan.

The tunnel with a super-large exit has a 80-meter stretch with fault surface of 249 square meters. The design is to reserve connection conditions for the future expansion with a new railway line.

"Due to the large span of the section, the technical team has innovated a new patented technology to effectively avoid the risk of tunnel collapse," said Wang Guanying, a project manager of China Railway 22nd Bureau Group Co. Ltd.

The tunnel is on the 508 km Yuxi-Mohan section of the Kunming-Wanzhou Railway, which is scheduled to be opened simultaneously with the Boten-Vientiane section in Laos to be completed by the end of 2021.

The cross-border railway is a major project built under the Belt and Road Initiative. The 1,000 km railway will slash the travel time between Kunming and Vientiane to half a day.