| Answer | Crossword Clue |
|---|---|
| shunters | travel back and forth shunted between the two towns |
| shunter | travel back and forth shunted between the two towns |
| commutes | travel back and forth regularly (as between a suburb and a city) |
| shuttle | bus, plane, etc., moving back and forth between two destinations |
| run | go back and forth ply the train runs between New York and Washington |
| arks | watertight container used in marine rescue operations, suspended from a hawser and hauled back and forth between a stranded or wrecked vessel and the shore |
