The Ferryman’s Troublesome Cargo

A traveller reaches a river with three awkward pieces of cargo: a wolf, a goat, and a basket of cabbages. His small boat can carry only the traveller and one of them at a time. He may also cross alone. Whenever the traveller is absent, the wolf cannot be left on the same bank as the goat, and the goat cannot be left with the cabbages. Either pairing would result in one item being eaten. All three begin with the traveller on the near bank and must arrive safely on the far bank. What is the fewest number of one-way river crossings needed?