NEW DELHI - A day after India launched the country's first bullet train project backed by Japan's Shinkansen technology, the country is divided on whether the US$19 billion project would benefit just a tiny fraction of the population, or eventually transform the ageing rail system.

Scheduled for completion in 2023, the project fired up the imagination of India's Twitter population, with most users raving about their #BulletTrain dreams.

Mr Bibek Debroy, a railway expert who is a member of the NITI Aayog, the government's main policy think tank, said, "95% people are those that travel in unreserved compartments, and not Rajdhani or Shatabdi. To them, this day counts for nothing."

He was referring to passengers travelling in the cheapest compartments of the existing "express" trains already in service in India, which have a top speed of around 150kmh.

Former railway minister Mallikarjun Kharge said, "It (the project) is not economically viable. The airfare between Mumbai and Ahmedabad is around Rs 2,000 (S$42). And it takes only 70 minutes. Your fare (for the train) would be between Rs 2,800 and Rs 5,000… so it will be profitable only if at least 1 lakh people travel by bullet train…. Otherwise it will incur losses," he said.

The costliest regular Indian railway ticket in India at present is 7,775 rupees for the journey from Trivandrum, in the southern state of Kerala, to New Delhi in the north, but that is an over 3,000km route. The new bullet train line will only cover a distance of around 500km.

Mr Debroy, however, told the NDTV news channel that criticism that the bullet train was papering over basic and wide problems with India's 164-year-old, accident-prone railway network was "vacuous".

He explained that the bullet train was not being funded at the expense of other rail projects. "Even when Japan helped us built the metro, they offered to do that or the bullet train. So the argument doesn't stand," he said.

He noted that while the government has come under heavy fire for a sharp rise in derailments in the last 10 years, the reason was that tracks were used heavily, so there was no time for basic upkeep. "You need to have at least 2 hours daily to just maintain the tracks. These lines are used perhaps every 5 minutes. So the only way is to delay trains. That's the trade-off for safety."

Mr Debroy also dismissed criticism over the line running from India's financial capital, Mumbai, to Ahmedabad, in Gujarat, which is Prime Minister Narendra Modi's home state.

"It needed to be 800-1,000 km stretch without any obstruction, a straight road. The only other one which perhaps has potential like that is Delhi-Chandigarh."

He expressed scepticism over whether the rail line would be viable by the time the loan granted by Japan was paid off in 50 years. "I don't think even the Japan bullet trains are viable. Nowhere is it viable, but the real estate around it can be viable," said Dr Debroy.

Opposition Congress party Member of Parliament Abhishek Manu Singhvi tweeted that the bullet train was a misplaced priority.

The Congress claimed it was not against "any project", but had seen "the Prime Minister uses big ticket projects, primarily for elections and pushes projects just before the polls".

State elections in Gujarat are due to be held by the end of 2017 or in early 2018.

"Announcement of packages and such projects have been a set pattern before every state election," said Mr Kharge.

"The Prime Minister and his Japanese counterpart laid the foundation stone today… We are not against any project or development. But what is your intention?" Mr Kharge asked.

On the other hand, Maharashtra Chief Minister Devendra Fadnavis, who is from Mr Modi's Bharatiya Janata Party and rules the state where Mumbai is located, described the laying of the foundation stone on Thursday as "historic".

"We are fortunate that Maharashtra is getting India's First #BulletTrain ! A historic moment in India's transformation journey!," Mr Fadnavis tweeted.

In an editorial, the Indian Express newspaper noted that India was getting the 50-year soft loan from Japan for the project at an interest rate of just 0.1 per cent, with repayment to only begin after 15 years. This translated into a virtual zero-cost loan. Also, giving a boost to Mr Modi's 'Make in India' programme, the project involves "localised manufacture" and "transfer of technology" as twin, complementary objectives.

Other than technology, the project will also result in capacity-building in India, creating a workforce capable of servicing similar high-speed corridors in India. Speed is another crucial benefit of the project, with estimates of daily ridership of around 36,000 in 2023. This is expected to enable the railway system to begin winning back higher fare-paying passengers on inter-city routes from the domestic aviation sector.

"We should be careful not to confuse leapfrogging technology development with elitism - whether it is mobile phones, satellite launches, regional air-connectivity or high-speed rail," the Indian Express editorial concluded.

On Twitter, users were mostly upbeat. "Many even questioned need for Metro. Criticism of #BulletTrain is similarly misplaced. It is a leap into future & a road to economic growth," tweeted Mr B.S. Bassi, the former police chief of New Delhi.

"The way Petrol prices are increasing, in future the only option to travel will be #BulletTrain," wrote user @BindasLadki.

Nevertheless, even as Mr Modi and Japanese Prime Minister Shinzo Abe launched the project, a group of farmers from Palghar district staged a protest, fearing acquisition of their lands, underlining the mixed feelings among Indians about the project.