Elon Musk's Hyperloop has a key flaw. Chinese scientists may have found ‘cure'

The Star

29-05-2025

Chinese scientists claimed to have solved a critical flaw in the futuristic vision of ultra-high speed ground travel, potentially salvaging vacuum-tube maglev technology and casting new light on the challenges faced by Elon Musk's Hyperloop concept.
A study published by China's peer-reviewed Journal of Railway Science and Engineering on May 16 showed that even minor imperfections – such as uneven coils or bridge deformations – would turn a journey into an ordeal, even in near-airless tunnels.
But the engineers – who are working at the world's first full-scale test line in central China – also said they found a way to slash turbulence intensity by nearly a half, reducing 'extremely severe bumps' to levels that were 'pronounced, but not unpleasant'.
The researchers, led by Zhao Ming from the maglev and electromagnetic propulsion division of state-owned China Aerospace Science and Industry Corporation (CASIC), said they used supercomputer simulations and scaled-down prototype tests for the study.
The team found that track irregularities and electromagnetic resonance were enough to trigger violent low-frequency vibrations in maglev cars travelling at the technology's cruising speed of 1,000km/h (612mph).
Using the 1940s-era Sperling Index, an international metric for ride comfort, the study showed that oscillations amplified at specific speeds, with a peak at 400km/h (249mph) reaching a level of vibration deemed 'extremely unpleasant'.
At the next peak, which occurred when the cars were travelling at 600km/h (373mph), the researchers recorded a Sperling Index of 4.2 – a level at which prolonged exposure to the vibrations would be harmful.
According to the paper, once the test cars reached cruising speeds of 1,000km/h, the vibrations lessened to 3.1 on the Sperling Index – defined as 'barely tolerable'.
A system that propels magnetically levitated pods through low-pressure tubes at near-supersonic speeds was first proposed by Musk in 2013, in a white paper that captivated engineers around the world.
Attempts to develop the Hyperloop concept at a SpaceX test track ended in 2023, after a number of technical hurdles, including the challenge of maintaining vacuum integrity and stabilising pods at extreme velocities.
In contrast, China is charging ahead, with the stakes transcending the engineering challenges.
Beijing has made ultra-high-speed magnetic levitation tech a national research priority that could not only redefine global transit, but also transform other critical sectors, including the race to achieve low-cost space launches.
The test facility in Datong, Shanxi province, represents Beijing's bet that China will dominate the next generation of public transport. To that end, its engineers have achieved airtight concrete, millimetre-precision joints and other hard-won feats.
According to the research team, without physical contact between train and track, the system's electromagnetic forces interact with the cabin in unpredictable ways. The result is resonance that would rattle passengers 'with extreme levels of instability'.
'Our research accounted for track irregularities, vertical bending of bridges, and single-frequency excitations induced by lateral irregularities in ground coils,' wrote Zhao and his colleagues.
'Under track excitation at an equivalent speed of 1,000km/h, the car body exhibited peak vibration amplitudes at frequencies of 2.6 Hz, 5.2 Hz, 7.8 Hz, and 10.4 Hz,' they added.
To overcome the problem, the Chinese team developed a hybrid suspension system combining passive air springs with electromagnetic actuators that are controlled by artificial intelligence.
The electricity-powered actuators adopt two cutting-edge control strategies, the paper said. One is a so-called sky-hook that mimics an imaginary damper linking the cabin to a stationary 'sky', using real-time velocity feedback to neutralise low-frequency jolts.
The other strategy, PID control, adjusts suspension forces via proportional, integral, and derivative algorithms, optimised by an NSGA-II genetic AI method to handle variable track conditions.
When tested on a 1:10 scale model with six-axis motion simulators, the system reduced vertical vibration intensity, measured as a root mean square acceleration, by 45.6 per cent under realistic track profiles.
Sperling Index scores stayed below 2.5 – 'more pronounced but not unpleasant' – across all speeds, according to the study.
The researchers said there were still some challenges ahead, such as scaling up the suspension tech for full-sized trains and ensuring that they would work in emergency braking and other extreme conditions.