Researchers in China say they have found a way to eliminate one of the biggest obstacles facing magnetic levitation (maglev) trains traveling at extreme speeds — the deafening “tunnel boom.” If confirmed at scale, the innovation could clear the path for commercial maglev routes capable of reaching 1,000 km/h, drastically cutting travel times on long intercity routes.
A Decades-Old Noise Problem
The research, reported by The Guardian, focuses on the intense shock waves produced when high-speed trains enter or exit a tunnel. Similar to the principle behind a piston, the air in front of a fast-moving train compresses quickly in an enclosed tunnel, sending low-frequency pressure waves toward the tunnel’s mouth. At very high speeds, these merge into a loud, concussive blast — the so-called tunnel boom.
This effect has long plagued not just maglev technology, but also conventional high-speed trains such as France’s TGV or Japan’s Shinkansen. For example, the TGV, which typically operates at 320 km/h, produces a much milder version of the boom than a maglev at 600 km/h, where the shock wave is strong enough to occur in tunnels as short as 2 km (compared with 6 km for traditional trains). Besides the noise, the boom can cause physical stress on tunnel structures and disturb wildlife and residents near rail lines.
Borrowing a Page From Firearm Silencers
The engineering team, part of the China Aerospace Science and Industry Corporation (CASIC), tested an approach inspired by how a gun suppressor reduces muzzle blast. They installed 100-meter-long porous buffers at the entrances and exits of tunnels, along with porous wall coatings inside the tunnel itself. These materials allow compressed air to escape gradually before the train enters, preventing the sudden pressure change that causes the boom.
According to the researchers, early simulations and scaled prototype tests showed a reduction of up to 96% in tunnel boom intensity. Larger-scale trials conducted in Shanxi province in late 2024 — where a prototype maglev reportedly reached near 1,000 km/h — confirmed the buffers’ ability to control shock waves without affecting train stability or speed.
From 600 KM/H to 1,000 KM/H
China’s newest maglev prototype is currently designed for 600 km/h operation, but CASIC officials say the tunnel boom breakthrough removes a key barrier to pushing speeds toward the 1,000 km/h mark. The technology also promises quieter operations, reduced structural wear, and improved passenger comfort.
If adopted on future lines, a route between Beijing and Shanghai could cut current train travel times from 4.5 hours to just 2.5 hours — matching domestic flight times but with far lower CO₂ emissions. China’s government has not yet confirmed commercial rollout plans, but industry watchers expect maglev to feature in future high-speed rail expansions, alongside the country’s already vast 48,000 km conventional high-speed network.
A Global Race for High-Speed Dominance
Japan remains China’s main rival in long-distance maglev technology. Its Chuo Shinkansen, using superconducting maglev tech, is designed to connect Tokyo and Osaka at 505 km/h in just 67 minutes. However, delays have pushed back the project’s original 2027 launch date indefinitely, leaving China in a position to seize a lead if it can scale up its new noise-control system quickly.
Both countries see maglev as a potential alternative to short-haul flights, offering similar travel times with lower carbon footprints. Whether China’s suppressor-inspired buffers become the industry standard will depend on how they perform in real-world service — but the results so far suggest the tunnel boom may no longer stand in the way of the fastest trains on Earth.
