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
Shock tube detonator Shock tube detonator A shock tube detonator is a non-electric explosive fuze or initiator in the form of small-diameter hollow plastic tubing used to transport an initiating signal to an explosive charge by means of a percussive wave traveling the length of the tube. It was invented by Per Anders Persson of Nitro Nobel AB, patented, and sold by them under the registered trademark Nonel, containing a small quantity of high explosive, but safer and more reliable than detonating cord with the same quantity of explosive. Another early product contained an enclosed combusting, non-detonating fiber. The most common product is