The capital Hanoi in the north and the southern commercial hub and major port of Ho Chi Minh City would each receive about half of the funds, much of which has yet to be raised from investors and development agencies.
Prime Minister Nguyen Tan Dung has asked officials to speed up preparations for the elevated and underground railway systems and focus on attracting overseas aid and loans for the projects.
Hanoi would receive 7.3 billion dollars to build seven railway lines, under the plan announced on the official government website, while Ho Chi Minh City, the former Saigon, would receive 7.5 billion dollars.
In Ho Chi Minh City, construction started in February for a train system set to include 19.7 kilometres (12.2 miles) of rail lines above and below ground, financed mostly with Japanese loans, officials said at the time.
French, German and Chinese companies have also expressed interest in plans to build Vietnamese urban rail projects.