We all fret about laying our rail straight on our layouts, but here's a picture of a freight siding next to one of our plants. The line is currently a BNSF line, but the siding has been there since the SLSF (Frisco) days 30 years ago. I know of at least three derailments here in the 30 years. It's hard to see, but there are some significant dips as well.