La Ngoc Khue, former Deputy Minister of Transport, said that a slower train is a far better option for the country at present, instead of the superfast train that comes with a very heavy budget burden.

Khue said that a train speed of 350 kilometers per hour (kph) as proposed by the Ministry of Transport (MoT) is redundant.

"As the TEDI-TRICC-TEDISOUTH consultancy consortium has estimated, actual demand in 2050 would only meet 40 percent of its capacity of 364,000 people a day. This means 60 percent of seats will not be occupied, while no cargo will be transported, a huge waste of capacity," he told VnExpress.

Railways should have the capacity to transport cargo. The World Bank has noted that Vietnam’s logistics cost accounts for 21 percent of its GDP, twice that of Thailand. The main reason is that Vietnam is far too dependent on roads while existing railway routes carry a small fraction of the total volume, Khue noted.

"Both China and Japan own the world’s fastest rails, but the former still has a 200 kph train and the latter has 140 kph trains to transfer goods, while the fast trains are used only to carry passengers between major cities."

Vietnam, with its limited budget, cannot construct both projects, Khue said, adding: "For these reasons, a single rail route that does both tasks is the only way."

Debates have broken out afresh on Vietnam’s first high-speed railway project after the Ministry of Planning and Investment (MPI) stated that under their investment proposal the project would only cost $26 billion, lower than half of the MoT's price tag of $58.7 billion announced last year.

The MPI’s price tag is lower because it has proposed a speed of 200 kph to carry both passengers and cargo, while the MoT wanted a 350 kph speed for passengers only.

In defending the MoT’s proposal, the TEDI consortium, hired by the ministry to conduct the project's pre-feasibility study, said that a speed of 350 kph is needed for the train to compete with aviation.

Pham Huu Son, a spokesperson for the consortium, said that a speed of 200 kph proposed by the MPI would only cut track costs by 10 percent and equipment costs by 26 percent, not by half as the MPI has claimed.

"We have made detailed calculations for different speeds. There cannot be such a big difference in costs," Son told VnExpress.

But the big price tag for the superfast train continues to worry experts, as it did when the high-speed railway was first proposed in 2010 at a cost of $56 billion, more than half of Vietnam’s GDP then, prompting the National Assembly to reject the project.

Khue said that the government is allocating around $1 billion for transport infrastructure a year, which would mean that for a price tag of $58.7 billion, the country will have to spend $2 billion a year for almost three decades on this project.

He asked: "Should Vietnam delay all other transport projects for this rail?"

Another concern is the dependence on foreign technology for the superfast train. Khue said that Vietnam is still struggling to complete its metro projects, which means it will have to be completely dependent on foreign technology for the express rail, putting local companies "out of the game."

"With a speed of 200 kph, local firms can master the technology for both infrastructure and manufacturing locomotives and cars, reducing the possibility of Vietnam only contributing cheap labor for the project."

The MoT said Tuesday it would clarify the differences between its price tag and that of the MPI to the government before presenting it to the National Assembly for approval.

Under the proposal by the MoT, the two sections – from Hanoi to the central town of Vinh and from the central town of Nha Trang to HCMC – would be built first in 2020-2030 at a cost of $24 billion, with commercial operations likely to begin in 2032. All sections were expected to be completed and operational by 2040-2045.