[Dudhbbh3343]

High speed trains in Japan have no screening at all. I imagine a well-placed bomb going off could have a similar number of casualties.

[bombcar]

https://en.wikipedia.org/wiki/2004_Madrid_train_bombings

https://en.wikipedia.org/wiki/Santiago_de_Compostela_derailm...

It could almost certainly be extremely deadly if it happens. Man, these were the two main ones I recall - Spain has had some bad luck.