Piston effect platforms with a single tunnel, however, air quality worsens when relying on the piston effect alone for ventilation. This still allows for potential energy savings by taking advantage of the piston effect rather than mechanical ventilation where possible. Tunnel boom is a loud boom sometimes generated by high-speed trains when they exit tunnels. These shock waves can disturb nearby residents and damage trains and nearby structures. The perception of this sound by humans is similar to that of a sonic boom from supersonic aircraft, but unlike a sonic boom, tunnel boom is not caused by trains exceeding the speed of
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