Intermodal Transport

Photo courtesy of ConundraOpens in new window In addition to the six basic modes of transportation, several intermodal combinations are available to shippers. Theoretically, intermodal transport combines the cost or service advantages of two or more modes in a single product movement. The more popular combinations include: trailer-on-flatcar (TOFC) (where the whole trailer of a truck is placed on the rain); container-on-flatcar (COFC) (often referred to as piggyback or roadrailers), where a container is placed onto the train, then later offloaded from the train and onto the trailer of a truck.

Such combinations can lead to transportation services with cost and service characteristics that rank between those of the single modes. Deveci et al. quoted the definition of intermodal transport from reference as follows:

The movement of goods in one and the same loading unit or vehicle that uses successively several modes of transport without handling of the goods themselves in changing modes.

If we exclude digital or electronic transport, which has a very low intermodal capability, we have 10 possible intermodal service combinations:

1. rail — road
2. rail — water
3. rail — air
4. rail — pipeline
5. road — air
6. road — water
7. road — pipeline
8. water — air
9. water — pipeline
10. air — pipeline

These are combinations in theory, but in practice only a few of them turn out to be convenient. The most frequent combined intermodal services are rail — road (“piggy-back”), road — water (“fishyback”), and road — air (“birdyback”).

Road — water combinations are gradually gaining acceptance, especially for international shipments of high-valued products. However, only rail — road combinations have seen widespread use throughout the world. The more popular combinations that we have explored are:

1. Trailer on flatter (TOFC)
2. Container on flatcar (COFC)
3. Roadrailers

Piggyback (TOFC/COFC)

Transporting a motor carrier trailer on a rail flatcar is referred to as TOFC service. It is also possible to transport only the container on a flatcar to omit the deadweight of understructures and wheels. Such combination is referred to as COFC service.

Although these two services are technically different, they are both referred to as piggyback service by most logistics executives.

Piggyback services thus combine the low cost of long-haul rail movement with the flexibility and convenience of truck movement. For example, the container is transported by train from Cape Town to Kimberley (at a low cost). It is then picked up at the station, loaded onto the trailer and taken to Wolmaranstad (demonstrating the flexibility of the system).

The cost of this combination is less than for trucking alone and has permitted truck movement to expand its economical range. Likewise, rail carriage has been allowed through this combination to share in some traffic that normally would move by truck alone.

Moreover, this combination brings door-to-door service convenience to shippers over long distances at reasonable rates. The above-mentioned features can interpret why piggyback service is the most popular intermodal combination.

Stock and Lambert mentioned the partnership between the Burlington Northern Santa Fe (BNSF) Railroad and J. B. Hunt Transportation Services as an interesting example of intermodalism. This partnership, which began in late 1989, combined a large railroad company with a national TL motor carrier. As a result, door-to-door intermodal services between California and the Midwest are now available to shippers.

Roadrailers

Roadrailer, also called trailertrain, is an innovative intermodal concept that was first introduced in the late 1970s. Although roadrailers appear similar to conventional truck trailers, they have both rubber truck tires and steel rail wheels, thus providing a combination of rail and motor transport in a single piece of equipment.

The trailers are shipped in the normal way via tractor over highways. By changing wheels for rail movement, the trailer rides directly on the railroad instead of being placed on a flatcar.

The roadrailer resembles a conventional motor carrier (truck) trailer, in that it has wheels. However, it has both rubber truck tyres and steel rail wheels.

Advantages of the Roadrailer

The advantages of this intermodal form of transport are that rail flatcars are not required and the switching time needed to change wheels is less than the time needed for loading/unloading the trailer from the flatcar.

In comparison with piggyback service, the main advantage of roadrailers is that rail flatcars are not required. Moreover, the required time for switching between highway and rail wheels is less than loading or unloading the trailer from the flatcar.

The major disadvantage of roadrailer is the additional weight of rail wheels, which reduces fuel efficiency and leads to higher costs when the roadrailer is traveling on the highway. As a direct result of high operation and equipment costs, the use of roadrailers is limited.

A more recent variation on this theme uses trailers equipped only with collapsible highway wheels. When moving by rail the trailers are placed on removable rail wheels. The removal of the rail wheels—which would otherwise make the roadrailer considerably heavier—means that a heavier shipment may be carried on the highway.

In addition to these options, there are other important entities in transportation systems. They are discussed hereOpens in new window.