Track sounds are a great idea especially those for high speed trains.
These sounds, though, don't all sound like the track. There's a lot of other ambient noise there too including the rattling of the passenger cars, and wind as the train goes under the bridges. I suggest, if you live near the tracks, that you go to an area without the other factors and capture the sound of the wheels on the tracks.
The thing to remember is you don't want your audio recorder (PC, 'Droid, iPad, etc. ) to be set too loud otherwise it will clip the audio and it will sound distorted.
I would go out and record some audio for you, but the high speed service we have around here is about 40mph with a speed restriction of 10mph for the Merrimack River bridge.
John