tunnel

In 1865 an outfit called the East London Railway Company bought the Brunel tunnel for £800,000, and in 1869 they opened a railway through it.

But very soon he grew to like it, for the Boy used to talk to him, and made nice tunnels for him under the bedclothes that he said were like the burrows the real rabbits lived in.

And one great chimney, whose long tonnell thence, / The smoke forth threw

Especially in the Eden Valley, trees create what is almost a green tunnel (particularly in summer).