The video below captured a suicide by train happening right in front of the cameraman in real time, and it demonstrates pretty well why encounters between humans and trains tend to be so graphic for humans.

The victims' clothes tend to suggest it was a woman and may have been rather young, though body size, as well as clothes, can be very deceiving, especially in some Asian countries where incidents involving trains happen the most. Either way, said person appears suicidal and determined to die. Choosing train as the means to end the seems to work well, and the train visibly obliterates the person upon impact. She/He even greets the train by raising His/Her arm, and after that, it's lights out pretty much within an instant.

---