Make sure you are a good ways off of the tracks. They spray herbicides constantly.
I live near a track and I've already seen a unit come through twice spraying a lot of crap. It's on the rails and comes through by itself with the sprayer on back constantly spraying while he heads up the tracks.
That's why you never see weeds or anything alive growing close to the tracks. And, if there happens to be a wind blowing in the direction of your plants... well.
Powerline rights of way are so-so, too. They cut the brush to the ground every few years depending on what part of the county you're in and how fast things grow. Some states spray rights of ways.
As teenagers in the 70's we found out the hard way with the powerline and gas pipeline rights of way. I found out later in years about RR tracks and was reminded just this spring again when I saw them spraying here.
Good luck! guerrilla growing is fun as hell, because it can be scary as hell if your state isn't legal.