We recently took the AVE high speed Spanish train from Madrid to Barcelona, a distance of 386 miles---with 168 tunnels (some of which are cut and cover). The longest tunnel is 15.43 miles. The trip took 3.5 hours including multiple stops.
The track is excellent with a complete absence of the "clickity clack" of old. Ties are concrete and at about an 18" spacing with impressive mechanical anchors to the bottom flange of the rail----no spikes to be seen
The speed is limited to 300 km/h (186 mph). At first they were running at a top speed of 330 km/h but it was sucking the ballast up off the rail bed and damaging the under carriage. Japan's bullet train also runs at a max speed of 300 km/h.
Comparing this to the bullet train---this ride is "less technical". The bullet train has tighter turn radii, but you only know you are in a turn if you look at the door way at the end of the car and see that it is out of plumb. The banking of the track is perfect for the speed. With far more available space this track can use bigger radii.
Both braking and acceleration are extremely smooth---I am sure that it is managed by a computer controller.
Without the screen at the end of each car showing trip information I would not have guessed our speed was as high as it was.