Ground vibration boom Ground vibration boom Ground vibration boom is a phenomenon of very large increase in ground vibrations generated by high-speed railway trains travelling at speeds higher than the velocity of Rayleigh surface waves in the supporting ground. This phenomenon, which is similar to a sonic boom from supersonic aircraft, was theoretically predicted in 1994. Its first experimental observation took place in 1997-1998 on the newly built high-speed railway line in Sweden (from Gothenburg to Malmo) for high-speed trains X 2000. At some locations along this line characterised by very soft ground (near Ledsgard) the Rayleigh wave velocity was as low as
Anti-shock body Anti-shock body An anti-shock body (also known as Whitcomb body or Küchemann carrot) is a pod positioned on the leading edge or trailing edge of an aircraft's aerodynamic surfaces to reduce wave drag at transonic speeds (Mach 0.8–1.0). Most jet airliners have a cruising speed between Mach 0.8 and 0.85. Wave drag can be minimized, for aircraft operating in the transonic regime (Mach 0.8–1.0), by having a cross-sectional area which changes smoothly along the length of the aircraft. This is known as the area rule, and is the operating principle behind the design of anti-shock bodies. Reducing wave drag improves