Clearly suicide, and with all sympathies to the individual, what a selfish way to do it.
I had a buddy who was Transport Police - he told me a few tales of railway suicides. Firstly the poor BTP guys had to hunt for all of the bits, and the drivers would often need counselling and be affected for a long time. The last i heard he was on long t term leave for PTSD.
So my sympathies not to the ingested, but to the drivers.