VIENTIANE, June 14 (Xinhua) -- The China Railway Guangzhou Engineering Group (CREC Guangzhou) has broken through a second tunnel along the China-Laos railway, securing steady progress in the construction of the railway project.

The CREC Guangzhou, a Chinese company which is in charge of the second section construction of the railway project, told Xinhua that the Ban Naven Tunnel was broken through on Tuesday.

The Ban Naven Tunnel is located in the country's northern town of Muangxay, Oudomxay Province.

The geological conditions of the 567-meter-long tunnel are very complicated with silty clay, sandstone and mudstone, thus posing challenges to the construction.

Since June 6, 2017, the CREC Guangzhou has assigned outstanding staff to the hilly tropical area and applied advanced technology and equipment in the construction of the tunnel.

The China-Laos railway is one of interconnectivity projects under the framework of the China-proposed Belt and Road Initiative. Construction of the railway began in December 2016 and is expected to open to traffic in December 2021.

The China-Laos railway has a length over 414 km, linking Mohan-Boten border gate in northern Laos and capital Vientiane. Operating speed on the railway is designed at 160 km per hour.