Makes you wonder whether the overhead of maglev is really worth it.
The big difference is that the TGV record set pretty much an upper limit on steel-wheel speed -- horrible vibration, and the wheel rims were close to supersonic, which would have led to more shock waves if they'd pushed it faster. Similarly, Formula One cars go a lot faster than regular road vehicles, but you wouldn't want to commute to the office in one! Whereas this maglev test demonstrated a technology that would be comfortably usable at this speed.
The TGV record is about half the speed of sound, which means the wheel rims are bordering on supersonic, so it's not a simple thing to talk about exceeding it.
The middle a the wheel moves at the same speed as the vehicle relative to the ground. (X + 0)
The top of the wheel moves at twice the speed of the vechile relative to the ground. (X + X)
Put another way, the top of the wheel must go faster than the vehicle or it does not rotate.
It's an odd diagram to draw out, as that result is pretty counter-intuitive.
[0] http://www.mobility.siemens.com/mobility/global/en/interurba...
This doesn't make any sense. The record is around 575 km/h. The speed of sound is 1225km/h. How would the wheel rim be travelling faster than the train? The while rim rotates 1m for every 1m the train travels, surely?
Can you explain what you mean?
To maintain that condition, the top of the wheel has to travel at twice the speed of the train. Imagine a point on the wheel. Each time the train moves ones circumference forward, that point also makes a circular trip of 1 circumference.
So at the top, when the motion of the point relative to the train is full forward, the net velocity is twice the train. At the bottom, when the motion of the point relative to the train is full backward, the net velocity is 0.
There are diagrams and further explanation here: http://physics.stackexchange.com/questions/48234/why-is-the-...
http://www.animations.physics.unsw.edu.au//jw/rolling.htm
Good stuff, and even has an interesting note about how train wheel rims acually go backwards as the wheel turns!
Then consider the amount of research that's been put into this, and the complex problems that needed to be solved -- it would probably cheaper to invest research into track that allows higher speeds with less maintenance (again incremental improvements possible).
Then consider that most of the speed from this maglev comes from the geometry of the track. It's all tunnels and bridges. That's a giant investment needed to get to those speeds; and conventional rail with that track geometry could be similarly fast.
It was discussed a little bit for the new high speed train line in Britain, but rejected for the reasons you state in your first paragraph. But Japan seems much less worried about reusing trains (different lines are usually operated by different companies with different rolling stock). And somehow they were able to get this project funded even though it will be many years until first service---maybe they just are more competent than the west when it comes long-term investments? :) So maybe the trade-off came out differently there...