She wasn't trying to kill herself, she thought it was her train so stepped forward ready to get on it but got too close and it hit her. She went under and has ended up losing her arm.
It's frightening to think fully grown adults can't even function now without managing to get in front of a moving train.
I jumped to my conclusion given that it's pretty hard to end up under a train without either intending to, or foul play. I'd wager she was doing **** on her phone and didn't bother to look up, and now has an eternal reminder of it