How can Walden be considered a response to the runaway train of nineteenth century

Thoreau can hear the train on the Fitchburg Railroad, located a hundred yards south of his cabin, next to the pond. He compares the train to a comet and suggests that men have so harnessed nature in making it they are almost a "new race" worthy of inhabiting the earth. The railroad has so influenced life in the towns that people measure time by the train's coming and going, and life goes on at a faster speed than before, "railroad-fashion."