As train speed continues to increase from high to ultra-high speed, engineering challenges are created for the soils beneath the track. When trains move at ultra-high speeds, ground surface waves are generated which can cause large vibrations in the track and the soil. This exhibit explores the issues surrounding high and ultra-high speed trains, with a focus on how research and new technology can solve them. It demonstrates Rayleigh waves and ground natural frequency effects, with visitors able to generate their own waves and explore how to prevent environmental problems.
When trains move at ultra-high speeds, ground surface waves are generated which can cause large vibrations in the track and the soil. Discover how new technology is helping us learn how to prevent potential environmental problems associated with high-speed trains.
When trains travel at high speed three main wave types are generated in the ground: compressive, shear and Rayleigh waves. Each of these waves propagate at a different speed. The slowest is the Rayleigh wave and it is possible that as trains travel at high and ultra-high speed they can catch up with this wave. This phenomenon is called ‘critical velocity’ and causes large vibrations in the track and the soil. These effects can also occur if the train characteristics coincide with ground or structure natural frequencies.
If these problems are not solved then train speeds may be prevented from further increases. It is therefore essential that these mechanisms are fully understood and suitable strategies are developed in a cost effective way.
As the track and train technology develops, operational train speeds of 350mph may be possible (the current train speed record is 357mph).
Lead image: A high-speed railway tunnel.