China develops 400 km/h bullet train

Chinese scientists say they have found a solution to help the CR450 bullet train run smoothly at 400 km / h by 2025.

China's fastest trains currently reach a top speed of around 350km/h and passengers usually have an extremely smooth experience with few moving objects inside the carriages, but that doesn't stop there, the country. planned to launch a new bullet train model by 2025 that can run 400 km/h - a speed that only some commercial supercars like the Bugatti Veyron are capable of.

At such high speed, even a small collision can cause the whole train to shake. During a long trip, such as the nearly 2,000-kilometer journey from Hong Kong to Beijing, persistent vibrations can make passengers seasick.

The team led by Professor Shi Jin from Beijing Jiaotong University said the problem could be solved by adjusting the height of the rails by just a few millimeters at some "sensitive points".

Shi and colleagues from the National Key Laboratory of High-Speed ​​Railway Technology in Beijing did computer simulations and ran tests on a test line, the results showing that their method really works. effective.

China's CR400 bullet train currently has a maximum speed of 350 km / h, but the new generation CR450 can increase this number to 400 km / h.

"The operating speed of bullet trains shows the level of technological development of a country," Shi wrote in an article published last month in the journal Railway Science & Engineering. "As trains go faster, the interaction between wheels and tracks increases, making existing measures to reduce ride vibrations less effective."

According to the team's calculations, the vibration felt by passengers during a 400 km/h trip will be 5% higher than at present. That might seem like a small difference, but it can increase the wavelength of the vibrations felt along the hull by 15%. If not effectively controlled, this can make passengers uncomfortable during the journey, even unsafe.

Research shows that lifting sleepers - concrete beams that support metal rails - by just a few millimeters can resist this impact. However, if the solution proves to be effective in practice, it will significantly increase the workload for railway maintenance crews, according to a Beijing-based high-speed railway engineer who was not involved in the study. . The engineer, who did not want to be named, said the 300-kilometer stretch of high-speed rail needed nearly a million sleepers to support it.

Trains with different speeds can operate on the same track, but each speed setting requires different sleepers. Existing Chinese safety standards also allow only a fraction of a millimeter error when adjusting the sleepers.

China has more than 40,000 km of high-speed rail in operation. To make them all suitable for 400 km/h trains will be a difficult task. However, it is necessary to find a solution soon because according to the government's 5-year plan, the new generation of high-speed trains CR450 will be completed and put into operation in less than 3 years.

Earlier this year, chairman Wang Feng of China's state-owned CRRC Changchun Railway Vehicles locomotive maker said the CR450 could even improve to reach speeds of up to 600 km/h.

However, in an article published in the journal Urban Mass Transit, he warned that trains traveling at 400 km/h have a stopping distance of 6 km, so additional measures are needed to ensure safety. passenger safety, such as automated driving and warning systems using artificial intelligence.

Wang also emphasized that CR450s are more environmentally friendly as they consume 18% less energy than current 350 km/h trains. Separate research by Chinese scientists shows that the carbon emissions generated by high-speed rail traffic are only 6% of that of air and 11% of that of cars.