They are the Hanoi - Lang Son line, which will extend to the Chinese border, and a line connecting Hanoi with Lao Cai Province, home to Sa Pa City, passing through the port city of Hai Phong and Quang Ninh Province, home to Ha Long Bay.
Both lines will become part of the highly anticipated north-south high-speed rail route.
The decision, announced Monday by the Government Office, is part of a broader strategy for the Red River Delta's development that seeks to enhance transport infrastructure, reduce congestion and promote economic growth.
It is seen as a critical step in modernizing Vietnam's transport network, facilitating better connectivity with China and supporting overall economic development goals.
The Hanoi - Lang Son high-speed rail line has been proposed several times in the past.
During a National Assembly meeting in January, delegate Tran Van Tuan from the northern Bac Giang Province said the high-speed line should be built soon because the cost is not too high and it is feasible to start work before 2030.
"Once completed, the line could become immediately operational since China already has a modern, integrated railway system."
Deputy Prime Minister Tran Hong Ha has more than once called for the development of a "synchronized, modern" north-south high-speed rail network allowing speeds of 350 kph in line with global trends.
It is related to national interests and so "we cannot delay and must have strong political determination to implement it."
In February 2019 the transport ministry presented a report to the government on the feasibility of the north-south high-speed rail project through 20 cities and provinces.
It will allow a top speed of 350 kph, while operational speeds will be 320 kph.
At the end of 2022 inspectors of the project proposed that the line should carry both passengers and goods at operational speeds of 225 kph and 160 kph.
The Politburo, the Communist Party's decision-making body, wants investment for it tied up by 2025, construction to begin before 2030 and its completion before 2045.