Navvy

Contraction of navigation, in reference to the navigation canals upon which these workers first toiled.

Full definition of navvy

(plural navvies)

(British) a laborer on a civil engineering project such as a canal or railroad

1909, B. Lindsay, Stories of the Universe: Animal LifeSuppose two lads, fresh from school, go out into the world to earn their living; one becomes a navvy and one a clerk. In five years' time these two young men will probably be very different in appearance from one another. The navvy will have developed his muscles; he will be broad-built, broad-chested, and strong.
1913, George Bernard Shaw, PygmalionHis proper trade's a navvy; and he works at it sometimes too—for exercise—and earns good money at it.

(British, intransitive) To carry out physical labor on a civil engineering project.

1974, Malcolm MacDonald, World From Rough Stones, 2013, unnumbered page,But by pretending to believe he's navvied before, I've given him double reason to drive himself hard.
1978, John Shaw Neilson, The Autobiography of John Shaw Neilson, page 104,Before my time of navvying I believe the times were still worse.
1995, F. R. Leavis, Ian Duncan MacKillop, Richard Storer (editors), F.R. Leavis: Essays and Documents, 2005, page 89,Three terms to use for George Eliot: the feminine imagination and sensibility; Intellect, the capacity for higher navvying; Intelligence.