This is a proposed very high speed train . The working is thus,
- It is a maglev train ( Magnetic levitation ),
- To eliminate air drag at high speeds, air would be sucked out of close enclosures within which the train would run. That is why the name – Vacuum Train
- The whole train line had to be under the ground to minimize sonic boom.
A proposed such train was being built by the U.S.A. to connect San Fransisco to New York . Its speed would be an unbelievable 8000 km/hr and take you from New York to San Fransisco in 1 hr only.
For some reason, it was dropped by U.S.A. but there is still interest in such a high speed Vactrain .