Turtles can’t derail a train. Turtles go squish. Even if you piled them up 6 foot high in front of the train.

This conjures an image of a very determined Bert the Turtle smoking a cigarette and declaring “I’m gonna derail that fucking train.”

Yeah “to stop them being blocked by the rail and giving up and going another direction” sounds much more accurate.

Looks like a covered utility trench, ironically with the cover off.

So a trench.