Containers being loaded onto stackcars.

The Stacktrain
Imagine if the farm wagons transported via rail from Long Island to New York City in the 19th century were still on the road today. In fact, until the advent of stacktrain technology in 1984, moving both the container in which goods were loaded (the top of the wagon) as well the means by which it rolled (the wagon wheels and frame) on a flatcar had not changed in nearly 100 years.

Certainly, some recent advances have made the transportation of products easier and safer. For example, containerized transportation providers used a chassis — a wheeled frame onto which the container is seated after being discharged from a vessel — so truckers could haul a container to and from a customer’s warehouse.

But loading both container and chassis onto a flat car was redundant, especially since a pool of chassis could be kept at some inland point where they were needed in order to facilitate pick up and delivery. Furthermore, traditional flatcars don’t allow for one of the most important efficiencies afforded by containers — the ability to stack them on top of each other like building blocks.

Today, a vast stacktrain network spans North America.

When APL developed the technology that made the stacktrain possible, such factors as eliminating the redundancies of TOFC, streamlining the transfer of containers from one mode to the next (from ship to train or train to truck), and maximizing the efficiency of containerized transportation were paramount. The answer came in the form of an articulated stackcar, made up of five individual platforms joined by fixed rigid connectors.

The stackcars developed by APL in the mid-1980s nearly doubled train capacity because containers could be stacked two high. Each stackcar could carry 10 containers on the same length of train that normally accommodated only 6 trailers.

In addition, removing the trailer frame and wheels (or chassis) from the containers substantially reduced weight. The decrease in weight made it possible to move more freight using fewer locomotives and crews.

And stackcars dramatically reduced the motion that had always resulted in damage to freight. This benefit impressed many shippers who had always associated rail transportation with costly claims. Stackcars virtually eliminated these specific types of movements:

• Slack action — produced by railcar connectors that extend and contract during train movement.
• Sway — resulting from high centers of gravity and the suspension systems of trailers.
• Vibration — created by the long distance between wheels on traditional flatcars.

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