Answer: culvert

AnswerCrossword Clue
CULVERTDrain
CULVERTCauseway conduit
CULVERTUnderground drain
CULVERTArched drain.
CULVERTConduit.
CULVERTConduit under a road
culvertto channel a stream through an arched construction or channel enclosing a drain or watercourse beneath a road, railway, etc
culvertdrain under a road, sidewalk, etc.