Xiao Qianwen, the Communist Party of China (CPC) secretary of joint working committee of the China-Laos Railway, told Xinhua on Monday that the accomplishment was another key progress made in tunnel construction of the railway project, after the drilling-through of Boten Tunnel, the first major tunnel over 5,000 meters along the China-Laos railway, in March.

The China-Laos Railway is a strategic docking project between the China-proposed Belt and Road Initiative and Laos' strategy to convert from a landlocked country to a land-linked hub.

The 414-km railway, with 75 tunnels of 198 km and bridges of 62 km, runs from Mohan-Boten border gate in northern Laos to the capital of Vientiane within an operating speed of 160 km per hour.