Vietnam has estimated that the cost of building a railway to China’s southern Yunnan province would be $7.2bn, Vietnamese state media report.

The 427km link would run from the border province of Lao Cai through Hanoi and Haiphong to Ha Long City, where tourists go to reach the celebrated limestone islands of Ha Long bay.

The line is intended to contribute to replacing the country’s antiquated colonial network with a modern high-speed system running along the length of the country.

Separately, Vietnam’s National Assembly is currently in session and will discuss approving the government’s $67bn plan to build a 1,541-km link between Hanoi and Ho Chi Minh City.

The 427km China-border railway, officially known as the Lao Cai-Ha Long railway, is now at the planning and design stage.

A team made up of the Transport Investment and Construction Consulting Company and the Transport Design Consulting Corporation has submitted its proposals to the transport ministry for review and approval.

The mountainous terrain of northern Vietnam is not friendly to rail construction, and the project is not expected to break ground before 2030.

There is, however, a strong demand for better communications because China is Vietnam’s main trade partner, with bi-directional trade worth almost £100bn a year.

By 2050, the line is expected to carry around 8.3 million passengers and 17.5 million tonnes of cargo.

A fast rail link is expected to boost Chinese investment in low-cost Vietnamese manufacturing.

Vietnam has approached China for technology and funding to improve the rail system on its side of the border.

During Chinese Premier Li Qiang’s visit to Hanoi earlier this month, the two countries signed an agreement to improve their cooperation on rail communications.

For its part, China has shown an interest in investing and building the link. As GCR reported in August, Wang Hai Huai, the chief executive of China Communications, visited Hanoi to personally pitch for a role on the Lao Cai scheme, as well as the North–South link.