Transport along the supply chain may be carried out point to point directly. It may also involve reloading of cargo between means or modes of transport. To describe the latter, we usually talk multimodality or intermodality. Let us sort out the issue.
Changing means of transport in the same mode
A transport process may be broken by changing means of transport, in the simplest form by reloading between vehicles of the same mode. For example, suppose cargo is carried on a pallet or in a container. In that case, the change may happen by simply reloading this unit between vehicles or including additional logistics operations that require opening and disassembling of those units. Dismantling a loading unit or the contents of a means of transport may be aimed at consolidation activities or activities consisting in mixing loads between these units or means of transport. It may also result from the need to subject the decomposed cargo to logistic activities with added value.
Reloading general cargo in a cross-docking system based on a network of terminals might be an example here. Many trucks arrive at the terminal at the same time. Trucks are then unloaded, and the loads in them are mixed with loads that arrived at the terminal in other trucks. Mixed loads are loaded onto trucks going to different destinations. This process is aimed at optimizing transport costs by making the best use of the cargo space of trucks. The cost of cross-docking operations is lower than the cost of transporting non-full truck loads directly from the place of origin to the destination.
Now to the rail transport. Breaking the transport process in rail transport happens, for example, at marshaling yards, where wagons from trains entering the marshaling yard are mixed. As a result, new trains traveling to different destinations are formed. A similar process takes place at container terminals. A container is transferred from one train onto another, either directly or via a transit storage yard.
Combined or multimodal transport
Combined or multimodal transport is the transport of goods using two or more modes of transport. The process does not necessarily involve the use of a standardized loading unit like a container on the entire route from the place of origin to the place of destination. But it of course might. For example, a combined rail-road transport can be a groupage palletized load that travels to a road-rail terminal by truck, then the pallets are unloaded from the truck on the road ramp, and transferred to the rail car on the railroad ramp.
Definitions of combined or multimodal transport that appear in the transport literature are not always consistent. The main assumption is that the main section of the transport chain should be by rail, inland waterway, or sea. The road carries out the first and last mile. The road route should be as short as possible. The European recommendation is, for example, that each road section may not be longer than twenty percent of the total transport distance carried out by other modes.
Intermodal transport is a special type of combined (multimodal) transport. On the entire route from the place of dispatch to the destination, the cargo is transported in one, and the same loading unit called an intermodal transport unit (ITU or in French UTI, unite de transport intermodal). The condition that distinguishes intermodal transport from combined transport is not to dismantle the container along the entire transport route. The reloading, therefore, does not so much refer to the load contained in a container, but actually only the container. From the perspective of the carrier, except for specific loads, such as, for example, temperature-controlled loads or dangerous goods, it does not really matter what is in the container. The use of standardized intermodal units in transport and reloading processes serves to standardize and thus accelerate these processes. Another condition postulated for intermodal transport is one consignment note for the entire route. It is rather a postulated but not practical condition for intermodal transport.
An intermodal transport process may involve transporting a road vehicle with an accompanying driver by another mode of transport (rail or ferry). An example of combined transport using rail transport is the so-called piggyback (German: Rollende Landstrasse) of full trucks on railway platforms. During the transport by rail, the truck drivers travel in a special passenger car. Hence the name “escorted”. This kind of transport is not economically efficient. Both the tractor and the driver are not working while traveling by rail. Tractor units and semi-trailers can be separated. An efficiently used tractor unit handles the longest possible mileage hauling cargo during an accounting year, while the semi-trailer can both act as a transport unit and a storage unit.
Considering cost accounting, a much more profitable type of intermodal transport is the transport of semi-trailers treated as intermodal transport units by rail on the main route. On the first and the last mile, the semi-trailer is coupled with two different tractor units. Obvious exceptions are transports used to overcome natural obstacles, for example, the transport of trucks in the Channel Tunnel, which takes place on the tunnel section in the piggyback system. Another example is the transport of heavy goods vehicles on RORO ferries across the Baltic Sea, where drivers use the time spent on the ferry for a night’s rest.