The following is the opening paragraph to The Girl on the Train:
She’s buried beneath a silver birch tree, down towards the old train tracks, her grave marked with a cairn.
Is the word down necessary? What is its semantic contribution?
It's telling us that the train tracks are "down" from the "here" of the narrator. Perhaps the downhill side of town, perhaps the old train tracks are in a railway cutting. It's giving us a sense of the physical geography and simultaneously giving us an emotional clue. It's not over towards the old train tracks: somewhere away from here, suggesting a distance. It's not up towards the tracks, suggesting effort to get there. It's down towards the old train tracks, a place you might fall to.