[CN] Maglev train researchers may have solved ‘tunnel boom’ shock waves

[latestnews]

Maglev train researchers may have solved ‘tunnel boom’ shock waves

Soundproofing buffers to be deployed on China’s latest maglev prototype

Chinese researchers may have resolved the long-standing “tunnel boom” issue as the country prepares to introduce its newest high-speed maglev train prototype. Capable of speeds up to 600 km/h (370 mph), the train faces challenges from shock waves generated when exiting tunnels. As the train enters a tunnel, air ahead compresses like a piston. This pressure surge forms low-frequency shock waves at the tunnel exit—termed “tunnel boom”—distinct from the sonic boom of supersonic aircraft. These waves can disturb nearby communities and animals and cause structural issues.

Researchers now report that new 100-meter soundproofing buffers at tunnel entrances, along with porous tunnel coatings, can reduce these shock waves by up to 96%. The buffers allow compressed air to escape, functioning similarly to a firearm silencer, enhancing safety, reducing noise, and improving passenger and environmental comfort.

Tunnel boom was already a concern for conventional high-speed trains (up to 350 km/h), but the problem escalates with maglev speeds. At 600 km/h, a tunnel just 2 km (1.2 miles) long can produce a boom, whereas this threshold is 6 km for slower trains.

China introduced commercial maglev service in 2004 between Shanghai Pudong Airport and the city’s outskirts using German Transrapid tech, hitting 460 km/h (286 mph)—still the record for commercial rail. Despite early excitement, national rail investment shifted toward conventional high-speed trains, expanding the network to 48,000 km (30,000 miles).

Maglev development resumed under state-owned CRRC, which unveiled the current prototype in 2021. Passengers describe a quiet, smooth ride with minimal mechanical noise, thanks to electromagnet propulsion.

Info based on https://www.theguardian.com/environment ... hock-waves Accessed Thu 7 Aug 2025

[Parrahub1]

Chinese lies the proposed Chinese SC maglev you have to push by hand and the EMS airport line has been reduced to 300 km/h.

The fastest one is the Japanese SC maglev proven between 1997 and 2011 for export.