The crowds, the chaos and the cows on the platform may soon be history. India's railways are to be given their most radical overhaul since the end of the British Raj with the introduction of high-speed trains on key lines – if an ambitious plan can be turned into reality.

A bill is to be introduced in parliament to allow funding, studies are under way and six proposed "high-speed rail corridors" have been identified. Instead of clunking in grimy, packed trains delayed by fog, elephants on the line or breakdowns, Indians and tourists can expect a rather different experience.

Japanese consultants have been in Delhi, India's capital, demonstrating the bullet train which travels at up to 200mph. "We are planning for the future. The pace of growth of the economy means high-speed trains will be a requirement. Not immediately perhaps but certainly in a few years," said Indian Railways' spokesman, Anil Saxena.

The most ambitious line would eventually connect the eastern port city of Kolkata with Delhi. Trains would stop at Varanasi, the holy city on the Ganges, and Agra, site of the Taj Mahal. Currently the journey can take 36 hours. A British firm has been commissioned to survey the first part of the route, from the capital eastwards to Bihar.

Other routes will link cities in the south and west such as Pune, Ahmedabad and Mumbai.

Overseas experts are not convinced that India either needs or can build high-speed railways. In France a mile of TGV track costs £15m, and much more through hills. In Britain the HS2 project has been priced at £33bn while California's bullet train is estimated at £70bn and will take more than 20 years to complete.

The total investment in India, even if land is cheaper, would thus be immense, experts say. New stations would have to be built in leading cities and there are big safety issues.

"The distances are massive, there are huge cities to go through or round and some very difficult terrain. And people are just not used to that kind of speed. Could they cope with that kind of technology?" said Christian Wolmar, a British transport writer.

Indian trains today average 45mph which, though an improvement on 35mph two decades ago, still puts them among the slowest in the world. Wolmar suggested implementing more modest measures to cut travel times on existing track.

Then there are the general issues blighting thousands of infrastructure projects – including desperately needed roads, power stations, canals, sewage plants and bridges – across India. Local experts say such scepticism is not justified.

"There is definitely a need for such initiatives and [high-speed rail] is theoretically possible here," said Dr Varadharajan Sridhar, a specialist in Bangalore who pointed to the success of the metro in the Indian capital – a project that many said was impossible to execute – and to the high-speed train network being built in China, India's regional rival. "There is no reason why we can't do what China has done," he said.

There have been safety concerns over China's high-speed train after a crash in July killed more than 40 people. But practical problems are nothing new to the Indian railway ministry. Its 1.25 million employees overcome all the usual hazards of daily Indian existence – from packs of aggressive monkeys through to natural disasters and Maoist guerrillas – to carry 25 million people to their destination every day.

The ministry is reputed to be the second biggest public sector employer in the world after the Chinese army and, with a revenue of £13bn, has even made a profit in recent years.

The railways have played a key cultural and historical role. Sudhir Kumar, author of a recent book on Indian railways, described the network as "the lifeblood of the country".

"The railways have been so very important in the independence struggle of India, in the unification of India and in the economic life that anything that gets their wheels turning quicker is to be welcomed," Kumar said.

Saxena, the Indian Railways spokesman, said that sitting on the roof of the trains, already forbidden though occasionally practised, would be discouraged.