Road Trains Roam the Backroads of Australia

Trains and the railways they run on are a great way to move lots of stuff, or lots of people, a long way. Steel wheels on steel rail can shift great loads at good speeds and railways remain a backbone of logistics for this very reason. The only problem is that they require a great deal of initial investment to build and plenty of maintenance to keep them functional over time.

These concerns can make a railway a difficult proposition when it comes to getting large amounts of goods in and out of remote areas. It’s a problem that Australia faces, with settlements far off the beaten track that are nevertheless in need of high-throughput freight connections. And if you can’t go rail, you go road… in a big way.

The simple fact of Australia’s geography is that there are towns and cities separated from each other by thousands upon thousands of kilometers. It’s often desirable to move goods to and from these places, along with remote mines and farms buried in the country’s vast, dry interior. However, it has never been practical to link all these disparate locales by permanent railways. The distances have always been too vast, and the freight volumes not quite high enough to justify the expense. At the same time, relying on trucks alone was seldom economically convenient.

The solution was straightforward, and surprisingly simple—bigger trucks hauling more trailers. In the local parlance, a road train consists of a prime mover (or tractor) that hauls two or more trailers.

The official definition from the Heavy Vehicle National Law excludes the standard B-Double configuration that is regularly seen across the country. Instead, a road train could be a longer A-Double configuration, or even one of a variety of combinations involving three or four trailers being hauled by a single prime mover, like a B-Triple or a BAB Quad. The A and B designations refer to the type of coupling used. A-type refers to drawbar-based couplings, while B-types are fifth-wheel or turntable-type couplings. A truck or road train setup is thus referred to by the couplings that make up the consist.

The longest road train configurations of three or four trailers typically range up to 53.5 meters in length and over 135 tons in weight, per the rules laid down by the National Heavy Vehicle Regulator, though even longer configurations are used in some specially-permitted or off-highway roles in mining or agricultural industries.

These long consists are typically pulled by large prime movers with anywhere from 500 to 700 horsepower and 1500 to 2000 pound-feet of torque. Ultimately, it doesn’t actually take a grand amount of power to get even a very heavy load moving; it’s the torque that helps the most, anyway. The bigger challenge is actually stopping, and that takes great care and makes road trains unsuitable for crowded roads. As far as applications go, road trains are used for hauling all sorts of goods and material across Australia. Common loads include livestock, ores, and general freight, as well as long chains of tankers for hauling bulk amounts of fuel.

Road trains also wear large signs front and back to indicate their status. Typically, this consists of large black text on a yellow background reading “ROAD TRAIN” or “LONG VEHICLE” depending on the jurisdiction. Classified nationally as heavy vehicles, road trains are limited to speeds of 100 km/h, except in NSW and Queensland where they are limited to just 90 km/h (except for B-Triples in the latter state). These regulations in part help to ensure that motorists know what they’re dealing with when coming across a large road train on the open roads in the Australian outback. It can take quite a long time to pass a road train at legal highway speeds, so motorists need to be aware when attempting such a manuever.

Largely by virtue of their length alone, road trains are restricted in where they may or may not travel. For example, in South Australia, B-triples that measure up to 35 meters long are only allowed to travel via specific routes to industrial and import/export hubs, to avoid them causing chaos in built-up metropolitan areas. Similar rules exist in other states and territories, too, where triple and quad configurations are allowed to operate at all. Notably, Darwin, capital of the Northern Territory, is unique in allowing triple and quad roadtrain consists to operate within a kilometer of the central business district. The city’s limited size and density, with a population of just 140,000, means that this isn’t the same practical disaster that it would be in other major metropolitan centres around the nation.

The “road train” terminology does have some purchase in other parts of the world. However, it generally refers to B-Doubles or other smaller consists compared to the Australian norm, where it only refers to the very largest configurations.

For example, countries like Spain, Sweden and Germany allow truck-trailer combinations up to 25 meters long, while trucks in the United States are largely limited to two trailer configurations up to 19 meters maximum. In these other jurisdictions, there is seldom the same economic incentive to haul excessively long trailer loads to maximise the efficiency of freighting to and from far-flung destinations. Greater traffic and other road network considerations also limit the practicality of extra-long consists in more densely populated regions.

However, in the outback of Australia, where the roads are so empty and the distances so great, the three- or four-trailer road train starts to make a whole lot more sense. Road trains aren’t going anywhere as long as Australia maintains its low population density and needs to haul goods to and from distant rural and regional areas. If you go far enough beyond the cities, or to the right freight terminals, you might just see some of these rolling behemoths ploughing their way across the landscape!