The Scarlet Plague:

THE way led along upon what had once been the embankment of a railroad. But no train had run upon it for many years. The forest on either side swelled up the slopes of the embankment and crested across it in a green wave of trees and bushes. The trail was as narrow as a man's body, and was no more than a wild-animal runway. Occasionally, a piece of rusty iron, showing through the forest-mould, advertised that the rail and the ties still remained. In one place, a ten-inch tree, bursting through at a connection, had lifted the end of a rail clearly into view. The tie had evidently followed the rail, held to it by the spike long enough for its bed to be filled with gravel and rotten leaves, so that now the crumbling, rotten timber thrust itself up at a curious slant. Old as the road was, it was manifest that it had been of the mono-rail type.