underpass

From under- +‎ pass.

underpass (plural underpasses)

1. A passage that crosses a road, railroad or similar obstacle in a tunnel underneath it.

   Synonyms: (UK) subway, flyunder

   • 1980, “Underpass”, in Metamatic, performed by John Foxx:

     Underpass / Underpass / Over all the bridges / Echoes in rows / Talking at the same time / Click click drone

   • 1986, “There Is a Light That Never Goes Out”, in The Queen Is Dead, performed by The Smiths:

     And in the darkened underpass / I thought oh God, my chance has come at last / But then a strange fear gripped me and I just couldn't ask

• flyover
• overpass
• dive-under