An adequate English expression when another train passes first

passing loop (UK) and passing siding (US)

Passing siding Main article: Passing loop A particular form of siding is the passing siding (U.S. and international) or passing loop (U.K.). This is a section of track parallel to a through line and connected to it at both ends by switches (U.S.) (points in international usage). Passing sidings allow trains travelling in opposite directions to pass, and for fast, high priority trains to pass slower or lower priority trains going the same direction. They are important for efficiency on single track lines, and add to the capacity of other lines.

siding on Wikipedia