Built to Travel: The Remarkable Capability of Road Trains

A road train, sometimes called a land train, is a configuration of truck and trailers that is able to carry large loads of cargo across challenging terrains. They are used in rural and sometimes remote areas in Australia, the United States, and Europe. Road trains are designed to move freight, and usually consist of a prime mover that pulls two or more trailers or semi-trailers.

The heritage of these unique transport assets dates back to the days when a single source of power (usually animals) pulled multiple wagons. They were first identified in South Australia in the mid 19th century, pulling such cargo as minerals to trading ports. Later, they were replaced by railways.

Over time, the technology evolved to become a vehicle powered by a single mover: an engine-driven truck, carrying two or three trailers over large swaths of land. The land over which they traversed was rugged and harsh, and ordinarily would not accommodate shipments over land. Railroads weren't built over such lands, and other convenient and well-maintained transportation lanes just weren't available.

Road trains are not common in the United States, though double and even triple-length trailers are. These are a version of road trains, but are limited to certain geographic areas and roadways. In the U.S., trucks on public roads are currently limited to two trailers. These two trailers may be 28-foot trailers connected by a dolly, with an overall limit of 63 feet end-to-end. Some states allow three trailers, although triple trailers are restricted to areas with lower populations, including Idaho, Oregon, and Montana. In the United States, triple trailer trains are used sometimes for long distances, less-than-truckload freight hauling, or in the Western states for moving commodities such as ore or aggregate.

In the 1930s and throughout the 1940s, Australia allowed road trains to transport freight and supplies into its Northern Territory. They replaced Afghan camel trains that had been trekking through the desert for centuries prior. Instead, mechanically powered road trains pulled two or three trailers that were just under 20 feet, with four axles on each. They required heavier horsepower (though not nearly as much power as today's standards).

After World War II, a road train was created from a U.S. Army surplus Diamond-T tank carrier. This tank carrier was jury-rigged to make self-tracking trailers. Wheel sets on each of the trailers could steer and navigate individually over very difficult-to-cross tracks. Such tracks would have been otherwise impassable, as they were narrow and tight. The road trains were also able to travel over shallow waterway crossings that existed throughout Central Australia in the early 20th century. These road trains and their self-tracking trailers were later used to transport machinery across the country.

Diamond T tank transporter. Source: M19 Tank Transporter. (2020, January 29). In Wikipedia. Retrieved from https://en.wikipedia.org/wiki/M19_Tank_Transporter

In Australia, road trains are still quite common, as it’s where many early road trains were developed. Today, it’s not unusual to see a four-trailer road train in the Australian Outback being pulled by a very powerful prime mover. “Road train” is a commonly used term in Australian transportation parlance, in contrast to more common semi-trailer arrangements, whereby one trailer, or a semi-trailer and the prime mover, are combined for train hauls. To date, Australia has the longest and heaviest legal road trains in the world. They can weigh up to 200 tons and transport cargo across very severe and harsh environments.

Throughout history, there have been remarkable road trains of varying lengths. Many, though, weren’t always so useful for long hauls but could be used for very short distances (mostly in breaking records). In 1989, a trucker was able to pull 12 trailers down the main street of a province in Australia. In 1993, another trucker used a 525-horsepower Mack Super-Liner to pull 16 trailers. His record was only to be broken just a few months later by yet another trucker who pulled 290 tons of cargo with an amazing 21-trailer rig that extended about 1,033 feet.

While longer road trains are commonly seen in Australia, shorter linked semi-trailers are used in Europe and the United States for transportation. They represent an unexploited category of over-the-road truck transportation that may be further explored as time goes on. In our global economy, an increasing amount of goods are being transported over greater distances. The competition to carry more per truckload is pressing and may prompt further technology development to better accomplish this need.

Time will only tell, but road trains symbolize that technology in transportation, and the innovation that we see in so many different areas of the world's commerce, can also be applied to transportation development when possible, so that better means are available to move goods.

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