[georgesimon]

Ideal adjustments (full compensation) are more uncomfortable.

Thought to be so, because there's a mismatch been visual and inner ear inputs. That is: you can see you're going around a corner, but you don't feel it. Resulting in motion sickness. Since all people have different tolerances of motion sickness, it's impossible to have a "correct" amount.

Almost all systems compromise between zero and full compensation, but passenger comfort is just one of many factors, and not the most significant. The discomfort on German tilting trains is probably because they are too close to "ideal".

[danhor]

Ideal (in the sense of fully compensated) is worse, but ideal in the sense of at the right time, with smooth interior motion, is much better. A "perfect" tilting train shouldn't feel much different than superelevation to the same level, but it does.

One of the issues with the German tilting trains is that they try to compensate up to 8° without track knowledge (BR 612) thus the first carriage (the one after that less so) swinging abruptly to compensate when entering or exiting a curve. Not sure how the class 390s solve that problem.

[georgesimon]

So you're saying the rate of change of compensation (or "jerk rate" when entering and exiting a curve, as people enjoy calling it) is worse on tilting trains?

I would love to see some data - I assumed this was a solved problem, but I wouldn't be too surprised if the tolerances were revised to fit the problem.

I forgot to mention the 'interesting' part of this problem: that the effects are measured cumulatively. That is, against passenger journey length. Drivers and other staff are not considered as far as I know!