I'd be very cautious about this method if you haven't researched it at all. Many of these attempts result in horrific injuries as the impact of the oncoming train can knock you around without cleanly severing or crushing your head; most particularly if survival instinct kicks in at the last second and you make any involuntarily movement. Just some 18 months ago there was a lot of publicity around a woman who suffered the loss of both legs whilst attempting suicide by train.
You may also wish to consider the trauma you could be leaving the innocent train crew to live with for the remainder of their lives, because you wish to end yours.
This is not to question your right (my view anyway) to end your life when seems best to you, just I'm not sure this method may be your best option.
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