Haulage is the business of carrying other people’s goods, usually in trucks (in Britain, lorries) or on trains. It is not one trip and not the truck itself; it is the trade. A factory that does not keep a big fleet will pay a haulage firm to move boxes to the shops. People say road haulage for moving goods by road, and haulage costs when they mean the price of that carrying. Though actually this is strongly British English. American speakers more often say trucking or freight. You will see it in business news more than in friendly chat.