There's no way that doesn't traumatise someone else though. It might feel like because something's behind closed doors or not literally in front of someone's face you can skip that consequence, but unless you jump off a boat in the middle of the ocean or walk into a crocodile someone will have to find you and it won't be easy on them.
That's why it's so fucked up that people are driven into all these bad options.
There are ways to be found by people who are trained in emotional compartmentalization who have the emotional resources to not be traumatized. (e.g., using
https://www.futureme.org/ to contact trained responders)
Trauma is not dependent on the experience itself (although some experiences are inherently more likely to traumatize), but based on the person's state of mind and ability to cope with the stress given their particular state of mind, experience, etc. This is why children are more easily traumatized and why even small things like getting a good sleep can reduce the likelihood of traumatization.
It will be traumatizing if the person is not expecting it, if they are tired (which many train conductors are), if they are untrained for it, etc. etc.
The trauma from a family member/other person learning of your death will also be very different from witnessing your death visually and directly.
There are ways to
ethically reduce or eliminate suicide-related PTSD. One of them is by not jumping in front of a train. I don't judge anyone that does this as afterall, we're all just trying to stop suffering, but I strongly urge against trains, jumping in public places, etc. for this reason.
Leave it to the people who have agreed/consented to recover bodies as part of their job to do so, if you you are able to (notwithstanding limitations to ctb method access. etc.).