A unit train is a freight train carrying numerous cars filled with the same commodity from a single point of origin to one destination. This method of shipping is very efficient and cost effective, but only works for large volumes of commodities. Many rail lines operate unit trains as a shipping option and may provide promotions and incentives to companies choosing this option. Often, the cars are identical, except for small variations, as they all carry the same thing and often come from the same transport company.
More classically in rail shipping, cars carry mixed commodities, or a train includes a number of cars, each laden with a different type of product. Additionally, trains drop off and take on cars as they travel. This allows for shipment of varying volumes of commodities to an assortment of destinations. It is also more expensive to implement. People must be paid to load the cars, as well as to handle cars as the train moves through different rail yards, splitting cars off and adding cars on.
The unit train is very cheap to run. Personnel load cars and link them together at the originating point, and the train goes straight through to the destination unless it needs to stop for fuel or to make way for other trains. This method is most effective when people need large volumes transported, often on a regular basis. For example, a unit train laden with coal could transport coal from a mine to a power plant, running on a regular schedule to keep the plant well supplied.
The more cars, the cheaper the unit train becomes to run. Companies can pool resources to pay for commodity transport on such a train if they are willing to arrange for further transport from an end destination to meet their needs. This can be less costly than arranging for private transport as part of a larger freight train. The unit train is also easy to secure and handle, as there are no special handling directions for specific cars, a concern when trains carry explosives, perishables, and other loads with particular needs.
People can usually identify a unit train with ease. The cars, if open, will all contain the same thing, and in the case of closed cars, will often bear similar markings. Such trains also tend to go straight through, rather than stopping, unless a stop cannot be avoided. Transit times vary, depending on distance and other factors, like whether the train will need to go slowly over tracks in poor condition or stop to allow a faster train to pass.
