1. We must be sure that we are comparing like with like. When you are talking such things as seating, onboard services, other passenger amenities, these items are irrelevant to the method of propulsion, so remove them from the equation. They can be just as good or bad regardless of what is moving the box containing the people.

2. Most of the information so far is in promotional literature. That is, a very one-sided view.

3. Regardless of propulsion, we are carrying a box or tube with people inside. A lot of the weight car floor and above will be immaterial to the method of propulsion. Therefore, claims about huge weight savings (TGV outweighs maglev "by a factor of 10") are somewhat (highly!?) dubious. I would be highly skeptical about anything above about 1.5, if that much.

4. The issue concerning the depth of subgrade preparation for the TGV appears to be somewhat of a "straw man." Subgrade preparation and the nature of the foundation for a viaduct structure are highly dependent upon ground conditions and subsurface materials. So far, no one has figured out how to build viaducts for lower cost than moving earth within the normal range of cut and fill depths.

5. The slim guideway may not be permissible in revenue service. No way does it provide the evacuation walkway provision requirements in NFPA 130. When you look at an ordinary open deck railway trestle or steel bridge you see in the portion from ties up all that is necessary to guide the train. That is only 10 feet wide and 18 inches high. What goes below is based on the requirement to hold the weight of the train and provide sufficient stiffness against guideway deflection. It is very unlikely that a maglev guideway could be any thinner than an ordinary transit system viaduct, and with legally required safety walkways it will not be any narrower.

6. Aerodynamic resistance of about half that of the TGV? OK, the Japanese Shinkansen latest versions are also understood to have aerodynamic resistance somewhere in this low range. That is to say, aerodynamic resistance is a function of attention to detail in the shape of the body and a long period of operation and experimentation. It is essentially irrelevant to the propulsion system.

7. Line side noise was not mentioned, but at high speeds a lot of the noise from the passing train is aerodynamic, essentially overwhelming the wheel rail noise that predominates at lower speeds.

8. Need for shielding for the safety of passengers and their computers. You don't want to have to remove your pacemaker wearing passengers in body bags. Even in rapid transit vehicles, if you set your laptop, or a briefcase with computer discs on the floor in the vicinity of the motorized axles you are likely to find that you have scrambled your files. Given the much larger magnetic flux requirement to levitate as well as move the vehicle, some very serious magnetic shielding will be a necessity.

9. The energy consumption appears to be higher than conventional rail for similar service. That was a significant factor in the Chinese decision to construct a conventional high speed system rather than a Maglev Shanghai to Beijing.

10. "Banking" and grades are usually limited by factors other than the operating characteristics of the full speed train. Superelevation is usually limited to 4 inches on must US railroads out of respect to the high center of gravity of piggybacks, auto racks, and double stack containers. This is not for normal running at speed, but in consideration of the forces on a stopped or low speed train on the curve. On passenger only lines, it is usually limited to between 6 and 7.5 inches, again due to consideration of passenger comfort and safety in case the train stops on the curve. This is the same logic used to limit the maximum speed and the reason that the speed limits on curves can be raised with tilt systems. The TGV has grade of up to 3.5%, Saluda hill was about 4.5% and heavy coal trains ran over that, and some transit systems go over 6%. Given high power factors and entering speeds there is no problem with steeper on the railway, except that it is a serious problem for the maintenance forces and in case a train stops on the grade.

11. "Skip-stops" can be and are used in current high speed railways. It is probably easier to do so on a railway than a Maglev. The Germans have standard turnout designs usable with diverging speeds of up to 220 km/h (136m mph) and the same design principles could be used to develop higher speed turnouts if needed. Usually a turnout good for 130 to 160 km/h (80 to 100 mph) is quite sufficient as it is placed at a position where the speed of the stopping / accelerating train will be below the turnout's allowable speed. Therefore, this is not a property of the Maglev system, but an operating plan applicable to either propulsion system.

12. The statement that "the Japanese send out thousands of workers every night to push the tracks back into place" is a major exaggeration. They do a 100% inspection of the Shinkansen track every night. But for the most part, it is exactly that, an inspection. The original sections are on ties and ballast, and yes, that part is very precisely maintained using a huge input of manpower. As for the slab track portions, it is doubtful that much is really done in the maintenance effort except check the fastenings. At 280 km/h your main sensations is that the countryside is going by very fast.

13. The acceleration rate dnsommer quotes is impractical unless you are going to have people strap in for acceleration and braking. It is 8.8 ft/sec^2 = 27% of gravity. For comparison, normal transit vehicle set maximum acceleration at about 3 ft/sec^2 = about 10% of gravity. Usual passenger train accelerations are about one-half of that or less, maximum. In the higher speed ranges, acceleration is power limited.

14. Saw the Discovery program on the tube under the Atlantic. Probably possible, but many technical, financial, political problems. Unlikely in our lifetimes. Vacuum tube railway lines / pneumatic tube people mover system ideas go back to the mid 19th century.

I have seen nothing in any discussion on train control systems, crashworthiness of vehicles, evacuation, other safety-related issues, etc.

Begin quotes:

Experts concede that the trains aren’t “greener” than existing electric-railway technology, notably the Shinkansen bullet trains that traverse the mountainous countryside and connect major cities at up to 300 kilometres an hour. Japan also uses monorails, trains and subways for intra-city transit. “The maglev is less efficient than the Shinkansen. It consumes about three times more energy,” said Satoru Sone, an engineering professor at Tokyo’s Kogakuin University.

But Sone said the maglev could someday replace airplanes for shuttling passengers around Japan because they emit one-fourth of the harmful greenhouse gases of a passenger jet. “Bullet trains are too slow to compete with planes. But the maglev might one day replace domestic air travel along some routes,” he said.