A tunnel is an underground or underwater passageway, dug through the surrounding soil/earth/rock and enclosed except for entrance and exit, commonly at each end. Tunnels are dug in types of materials varying from soft clay to hard rock.

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Construction of Railroad Tunnel, 19th Century

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Size: 3900px × 3573px
Location:
Photo credit: © Science History Images / Alamy / Afripics
License: Licensed
Model Released: No

Keywords: 19th, art, bored, century, civil, colorized, commonly, construction, dug, enclosed, engineering, engraving, enhanced, entrance, exit, exportedakg, figuier, grandes, history, inventions, les, louis, man, passageway, railroad, railway, soil/earth/rock, surrounding, technology, train, tunnel, tunnels, types, underground, underwater, workers