This is an old idea that keeps cropping up. It's been mentioned in various science fiction stories going back at least to the early 1980s, and patents have even been issued [ www.et3.com - called Evacuated Tube Transit, but essentially the same idea]. I personally filed a Patent Disclosure in 1983, unaware of the prior public publishing of the idea. It would appear that patenting of the general idea is no longer valid, though there would be plenty of room for specialized patents. The IDEA is: A tube is evacuated of almost all air. Inside are bottom, top, and side rails [or possibly in a Y configuration]. On the rails ride pressurized cars - passenger cars or cargo cars - that can move at very high speed due to almost zero air resistance, and upper/side rails to prevent derailment. Likely the cars would have a wheel-structure or mag-lev structure, spaced between each car and riding on the rails, forming a long train of cars. An electric motor/generator system would accelerate/decelerate the train of cars. Top speeds would be several thousand Kilometers per hour. Most systems theorize mag-lev, though even steel wheels would work - particularly if they are mag-lev and kept spinning at an appropriate speed! This might work well in an initial stage for delivery of small cargo, such as mail and small parcels, in which the pipeline is less than 1 meter in diameter. As experience is gained on maintaining the vacuum, and making pressure-locks fully functional, it could be scaled-up to 2-3 meters in diameter, with "cars" in which passengers are in a reclining position. Since such a system would require a huge financial expenditure, and decades of development, it would appear that only a large national/international government commitment could make it work. Is this something worth pursuing? Certainly the energy savings would be tremendous, once such a system were in operation. Could this be targeted for completion by mid-century? Ideas and comments are welcome.