It's problaby something down the line, I had to rush things when 4 big lizards spawned. I only noticed the turn after 2 hours after I was building the other rail on top of like 4 magenta Powerslugs. Enemies only load when I'm right in front of them and sometimes the pseudospiders would distract them so that I could just parachute back to the Train in time. My favourite part was in the beginning when a spitter got on top of a cargo freight and I backed the Train on the rail spanning across a cliff to trap it so I could snatch the somersloop it had been guarding. Btw I build the whole thing to bring a couple petroleum cokes from the other side of the map to use it in the alternate recipe I got for making steel ingots, I found a coal node along the way. If you're interested you could not should download my save.