I get a lot of intrusive suicidal thoughts that are impulsive which seems to me what you are getting right now. I get a lot of trains too and will always get the thought of jumping while I wait. That's been happening for years now.

Do you think you are likely to act on these thoughts? While thoughts can be scary to live with, if it's just a thought with no intent it's not necessarily that dangerous. Are you in therapy? It might be worth mentioning to your therapist if you are, they might be able to help bring you back from those thoughts so you know with certainty that you won't act on them.