Photo taken on March 21, 2019 shows the drilling-through ceremony of Boten Tunnel along the China-Laos railway in Boten of Laos. (Xinhua/Wang Jingqiang)

BOTEN, Laos, March 21 (Xinhua) -- A Chinese railway engineering company on Thursday drilled through Boten Tunnel, the first major tunnel over 5,000 meters along the China-Laos railway.

This marks an important milestone in the construction of the project. The Boten Tunnel, with a length of 6453.5 meters, is among the 10 major tunnels longer than five km along the China-Laos Railway.

Khamsouk Bounyavong, vice president of Lao People's Revolutionary Party Central Committee's Inspection Committee, and Ju Guojiang, chairman of the Laos-China Railway Co., Ltd, the joint venture in charge of the construction and the operation of the railway, attended the drilling-through ceremony in Boten on Thursday.

The tunnel has to pass through unfavorable geology such as karst, bedding rock, fault fracture zone, gypsum, carbon mudstone, and water inrush, and it varies, thus creating lots of difficulties to the Chinese engineering company, China Railway No. 5 Engineering Group (CREC-5).

The Boten Tunnel was selected to be built as a high-quality demonstration model for the railway project. Since March 2017 when the construction started, the Chinese engineers have strictly implemented the managing requirements of mechanization, industrialization, informatization and profession.

The CREC-5 strengthened the on-site safety and quality control and extensively applied tunnel construction kits, vigorously carried out scientific and technological research, actively promoted the application of new technologies, and paid close attention to process management so as to ensure the safe and orderly advancement of tunnel construction, and lay a solid foundation for the Thursday's victorious breakthrough.

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 414.332-km railway runs from Mohan-Boten border gate in northern Laos to the capital of Vientiane within an operating speed of 160 km per hour.

The electrified passenger and cargo railway is built with the full application of Chinese management standards and technical standards

The project started in December 2016 and is scheduled to be completed and opened to traffic in December 2021.