Source: adapted from W.J. DeWitt. Freight Transport & Modes in Global Logistics & Supply Chains.
Several modal options are available to support the mobility of freight depending on what is being transported, the concerned distance, and modal availability. Freight modal options are more diversified than passengers considering the variety of cargoes, including raw materials, parts, finished goods, and food (perishable) products. Unlike passengers, different types of cargo often require different conveyances, which precludes uniformity.
- Air. Air freight has seen a growth similar to that of passengers, which has been significant. Air packages are generally carried in unit load devices, either on dedicated freight planes (freighters) or in the bellyhold of scheduled passenger flights. Heavy loads, such as vehicles, require specialized cargo planes and are commonly used by the military and for emergency deliveries.
- Truck. Trucks are highly flexible vehicles able to carry almost every type of cargo over short to medium distances. Package trucks are commonly used in urban freight distribution since they carry various cargo (in boxes or pallets) servicing a fluctuating demand. Less than truckload (LTL) carriers usually consolidate and deconsolidate loads coming from different customers, which is common in the parcel carrying business. Truckload (TL) transportation carries large volumes that have been broken down into the largest possible truckload unit; several truckloads are required to fulfill an order. The variety of modal options is related to the technical requirements to carry specific cargoes such as bulk, liquids, or containers. Trucks using chassis are able to carry domestic (usually 53 feet in North America) and ISO containers (20 and 40 feet).
- Rail. A unit train carries the same cargo between one origin and one destination, with several carload configurations possible depending on what is being carried. There can be unit trains for coal, grain, cars, or containers; they carry a single commodity. Trains can also be assembled with different carloads servicing different customers, origins, and destinations. However, this is more costly and time-consuming. Containerization had significant impacts on rail transportation and spurred the development of intermodal rail services. The first concerns trailers on flatcars (TOFC) where a complete truckload is loaded on purposely designed flatcar (“RoadRailers” are an adaptation of this principle). Such modal use has declined substantially. The second involves carrying domestic containers on well cars that are also designed to carry ISO containers. Unit trains are common for the transport of containers between large gateways and inland centers.
- Maritime. Through applying the principle of economies of scale, maritime shipping has developed specialized ships to carry breakbulk, dry bulk, liquids, vehicles (RoRo), and even liquid natural gas. Container shipping has also become a dominant maritime modal option supporting commercial transactions with multiple origins, destinations, and cargo owners. The standard ISO containers of 20 and 40 feet are the main unit sizes, which have been adapted to carry refrigerated goods (reefers) and even liquids (tank containers). Still, the dry maritime container is the most dominant container cargo unit.
- Inland / Coastal. Inland (fluvial) or coastal maritime services are prevalent where major river systems are reaching deep inside a continent (e.g. Mississippi, Rhine/Danube, Changjiang, Amazon), where a country is an archipelago (e.g. Japan, Indonesia, Philippines) or with long coastlines (e.g. Northern Europe / Baltic, Mediterranean, American East, Gulf and West coasts). In some cases, river/sea ships have been designed to link fluvial ports separated by an oceanic mass, such as in Western Europe (e.g. Germany / England). Barges designed to carry specific commodities (e.g. grain or coal) can be towed along rivers or coasts. Containerization has also incited the design of specialized container barges that carry containers between major coastal ports and inland destinations.
- Pipelines. Represent a completely separate freight distribution system where liquids (particularly oil) and gases can be pumped over long distances. Pipelines can also be used to carry small quantities of freight, namely through pneumatic tubes (e.g. documents). A few systems using pneumatic tubes to collect wastes have also been implemented.