Academics have responded to Elon Musk's hotly-anticipated transport concept, Hyperloop, by calling it unrealistic and "hyperloopy".
The Paypal, Tesla and SpaceX founder said the near-supersonic service would use magnets and fans to fire passenger-carrying capsules floating on a cushion of air through pressurised tubes.
Rod Smith, a professor of engineering at Imperial College London, told Techworld that the project is very unlikely to take off, even though nothing outlined in Musk's 57-page proposal violates the fundamental laws of physics.
Indeed, the concept of capsules being fired through a pressurised tube isn't a new one with "the father of modern rocket propulsion" Robert Goddard first proposing a 1,200mph vacuum system between New York City and Boston in 1909. Several other proposals have followed but none have taken off due to the technical difficulties of maintaining such a system, according to Smith.
"It's not based on strong engineering principals," said Smith in reference to Hyperloop. "I'd go as far as to call it fantasy."
Smith's main issue with Musk's proposal relate to the entrepreneur's energy calculations. Musk claims Hyperloop will use a similar amount of energy to high-speed rail but Smith believes this is a miscalculation. "To get a narrow projectile down a thin tube requires a lot of energy," he said.
Smith also said that it would be very hard to earthquake-proof Hyperloop because no matter how strong the tubes can always be twisted out of alignment, no matter how strong they are.
Meanwhile, Tim Schwanen, professor of transport studies at Oxford University, told Techworld that the spread of people across California does not support Musk's vision.
"With the exception of the stretch of the line through the San Francisco Bay Area, the area traversed by the line is characterised by heavy urban sprawl," said Schwanen. "So building densities are low, meaning that access and egress time between stations and actual origins and destinations will be considerable for most users, partly cancelling out the travel time gains achieved by the new system."
He also believes that it will be difficult to raise the finances for the $6bn (£3.9bn) project.
"The project will be considered extremely risky by policy-makers and the (private) institutions that will have to be involved in funding the construction of the system, such as banks and institutional investors, as this is an unproven technology," said Schwanen.
He added: "Politicians — especially Republicans — will not be very eager to invest in what is no doubt a very costly project given the dire state that California's public finances are in at the moment and the more general political climate in the USA at the moment."
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