Thank you for the warm welcome and the kind comments! Perhaps I will have to post an introductory note in the Train Tech registry too.
I will try to address some of the questions raised:
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+ How many (standard?) 9V motors are used to drive your trains, e.g. ICE 3, Thalys or Eurostar?
Each train has two motors, one at each end. These are standard 9V train motors and haven't been modified in any way.
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+ How long is your loop in total numbers of straight 9V tracks?
The main loop in the first video (TGV) was about ~35-40m -- I never measured it exactly, but I know I used ~350 pieces of straight track including sidings. The second layout (crash video) was shorter, about 125 straights for each loop, giving ~250 straights for the double loop. I realized a while ago that to truly enjoy these trains, I would need a lot of track, so I gradually built up this amount over many years. I have plans for a larger double loop layout using ~500 straights, but now I need find the time to go and try it out.
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+ How many train track contacts do you use? (One each XX pieces of track?)
Due to the increased electrical resistance provided by the small area of contact between each piece of straight track when they put together in long curves, I have found many electrical connections to the track to be very important. In the first layout, for example, I used a contact every 4 m (~30 straights) in the curved areas. One can get away with a lot fewer contacts on the straightaway sections since there is more contact between track pieces.
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+ Do you use any customized speed regulators? If so, what is the customization about?
For the TGV video, which I made a little while ago, I used three stock 9V speed regulators in series, each powering a different section of the layout. This was OK, but I knew the resistance from the layout was still holding the trains back a bit. Now I have some customized speed regulators where the current has been increased from 1 amp to 3 amps at 9V. This was used in the second video (train crash), with one modified speed regulator for each loop, which is much nicer. The result is particularly apparent with the ICE 3, as it also has 5 lights, which, combined with the two motors and the loss in the track, meant it could not get enough current from a standard 1 amp speed regulator to go at full speed. This shortcoming is solved with the 3 amp speed regulator, which I obtained from the seller
ELECTRO-BRICK on Bricklink. He is a great guy and I highly recommend his work -- he can also modify your speed regulators if you don't need a new one.
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I wonder if such high speed experiences would be possible with Power Function trains also? If you use multiples of the latest 9V train motor (
http://www.brickset....ail/?Set=8866-1 ) you might also get fast, long trains?
This isn't something I've tried (unfortunately I don't have any such parts), so I would be interested to hear from anyone who has tried making fast trains with the new Power Functions elements.
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Those big radius curves....do you just "bend" many straights ?
Each straight is connected together with a hinge plate on one side and a 1/2 stud offset on the other side, which is achieved with a jumper plate. Eventually this gives a curve with radius ~1.9 m. HoMa wrote an article in Railbricks issue #1 describing this method, and I would encourage you to give it a try!

Eventually I might try to make some custom track if I ever have a permanent location for a layout, but for now this method works great as it allows for long curves that can still be easily disassembled.
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But I wouldn't dare crashing my favorite trains purposly in front of the videocamera.
(too afraid of permanent damages or scrathes...)
Haha yes, I thought about this afterwards, since I might have broken the lights on the ICE 3 in the crash.

Fortunately they were OK. In any event, the beauty of LEGO trains is that you can just put them back together again! Parts can be replaced, decals can be reprinted, so have some fun and stage a terrible crash!
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By the way how can you move in your home for not stepping on train track, like even in the kitchen !
Yes, this is why the layouts are only temporary... it is difficult to find a large enough open area sometimes! The others in my house just stepped around carefully for a few days... very kind of them.
Thank you once again for your comments, and I look forward to participating in this community more in future!
This post has been edited by lego9vtrainfan: 17 January 2010 - 10:14 PM