When I worked for BART we had people jump in front of trains a couple times a year. As far as I know everyone jumped (versus being pushed by someone). Some actually survived by landing between the running rails, but that was clearly the exception.

Medical emergencies on board trains were daily occurences. You arranged paramedics to meet with the train at the next station they were due into. When firefighters responded, they would barricade the train doors in the open position to avoid being taken for a ride to a different station. As long as the doors were open, the train wasn't going anywhere. The train controllers were not happy when this happened, as it would back up trains behind the train with the victim on board.