[lovemenot]

I have used that particular Shinkansen route at least thirty times in each direction. Admittedly not so much recently. I have also traveled by high speed rail in Northern Europe, for comparison.

Your experience on the Shinkansen is very different from mine. The only explanation I can imagine is that your train was travelling slowly, which can happen - rarely - in typhoon season.

Otherwise, which high speed lines have you used that did not induce seasickness in you?

[reaperducer]

It wasn’t the slow train. I had my wife with me so I splashed out for the fastest train available. It was around 7am, so I assume it was rush hours.

I’ve taken a few high speed routes around the world. KTX between Seoul and Busan. The entire Eurostar route. Others I can’t remember off the top of my head.

The best experience so far has been Trenitalia between Rome and Naples.

[lovemenot]

I did not mean to imply that slower trains such as Hikari or Kodama on that route might make one nauseous. Rather on very rare occasions, a too-slow train would let you feel the side-to-side as it banks.

Well anyway it seems to have been just a one-time experience, from which you've managed to deduce both generality and cause.

Again, from experience that's not common, so perhaps a more charitable explanation than system degradation might have been warranted. Certainly the rolling-stock is much newer than the system. The Nozomi you used would have been, at a guess 15 years or younger.