Road train
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A road train is a trucking concept used in remote areas of Australia, the United States, and Western Canada to move bulky loads efficiently.
[edit] Overview
A road train consists of a relatively conventional prime mover, but instead of pulling a single semi-trailer the road train pulls more than one of them.
Australia has the largest and heaviest road-legal vehicles in the world, with some configurations topping out at close to 200 metric tons. The majority though are between 80 and 120 tonnes. Two-trailer road trains, or "doubles" are allowed in all Australian states except Victoria and Tasmania, and into two capital cities - Adelaide in South Australia, and Perth in Western Australia. Three trailer road trains (triples) operate in western New South Wales, western Queensland, South Australia, Western Australia and the Northern Territory, with the last three states also allowing AB-Quads (3.5 trailers). Darwin, NT, is the only capital city in the world that will allow triples and quads to within 1km of the CBD.
Road trains can be unwieldy, and driving and maneuvering them safely is only possible because of Australia's tough regulations regarding licensing and driving experience. The multiple dog-trailers are unhooked, the dollys removed and then connected individually to multiple trucks at "assembly" yards when the road train gets close to populated areas.
Road trains are used for transporting all manner of materials, with livestock, fuel, mineral ores and general freight the most common. Their cost-effective transport has played a significant part in the economic development of remote areas, with some communities totally reliant on a regular service.
Overtaking a road train can be quite difficult (and, on Australia's many dirt roads, often impossible). Patience, assistance from the driver, and large amounts of clear road are required. Although it is illegal, many road train drivers help by blinking their right-turn indicators a couple of times to indicate that the road ahead is clear. Road train and truck drivers can see much further than cars.
When the road train trailers are empty, and there is no available freight, it is common practice to stack them. This is commonly referred to as "doubled-up" or "doubling-up". Sometimes, if many trailers are required to be moved at the one time, they will be tripled stacked, or "tripled-up". This method only works with flat-top trailers.
In the United States, trucks on public roads are limited to three trailers (in some states only two), and the term "road train" is not commonly used. Triples are used for long-distance less-than-truckload freight hauling (in which case the trailers are shorter than a typical single-unit trailer) or resource (such as ore or aggregate) hauling in the interior west. Triples are typically marked with "LONG LOAD" banners both front and rear.
In the far north of Canada, road trains are used to transport materials on winter roads, when the lakes are frozen over.
[edit] World's longest road trains
In 1999 the town of Merredin, Western Australia made it into the Guinness Book of Records, when Marleys Transport made a successful attempt on the record for the world's longest road train. The record was created when 45 trailers, driven by Greg Marley, weighing 603 metric tons and measuring 610 metres were pulled by a Kenworth truck for 8 km.
In 2003, the record was surpassed near Mungindi, New South Wales, by a road train consisting of 87 trailers and a single prime mover (measuring 1235 metres in length).
The next record was 1,442 metres, set by a driver in Kalgoorlie, Western Australia in a Kenworth owned by Doug Gould.
In 2006, a truck with 104 semi-trailers (at a length of 1,474.3 metres) claimed a new record at Clifton, Queensland.
[edit] Trailer arrangements
[edit] B-double
A B-double is a semi-trailer attached to a fifth-wheel mounted on the rear of another semi-trailer.
[edit] C-train
A C-train is a semi-trailer attached to a fifth-wheel on a C-dolly. The C-dolly is connected to the tractor or another trailer in front of it with two draw-bars, thus eliminating the drawbar connection as an articulation point. One of the axles on a C-dolly is self-steerable to prevent tire scrubbing.
[edit] Dog-trailer
A dog-trailer is a trailer that has a convertor dolly hooked in front of it, with a single A-frame drawbar that fits in the ringfeder on the rear of the trailer in front, giving the whole unit 3-5 articulation points and very little roll stiffness.
[edit] Rules and Regulations
[edit] Signage
A road train has signs front and back in large black letters on a yellow background reading "ROAD TRAIN".
[edit] Combination Lengths
- B-Double- 26m max.
- B-Triple- 33.5m max.
- Double road train- 36.5m max.
- Triple and AB-Quad road trains- 53.5m max.
[edit] Operating Weights
Operational weights are based on axle group masses, as follows:
- Single axle- 6.0t (metric)
- Tandem axle grouping- 16.5t
- Tri axle grouping- 20.0t
Therefore, a B-Double would weigh 62.5t (6 + 16.5 + 20 + 20). A double road train would have an operational weight (without concessions) of 79t (6 + 16.5 + 20 + 16.5 + 20). A triple is 79t + 36.5 (16.5 + 20), giving an all up weight of 115.5t. Quads weigh in at 135.5t(extra 20t). Concessional weight additions (1 - 2.5t per group) can see a quad end up weighing 149t. If a tri-drive prime mover is utilised, along with tri-axle dollys, weights can reach nearly 170t.
[edit] Speed Limits
The Australian national heavy vehicle speed limit is 100 km/h, excepting:
- NSW, Queensland and South Australia, where the speed limit for ANY road train is 90 km/h;
- Western Australia and the Northern Territory, where the speed limit for road trains is 100 km/h.
[edit] See also
- Air brake (road vehicle)
- Brake
- Jackknifing
- Semi-trailer truck; this article covers large trucks such as road trains and articulated lorries
- Transport
- Fifth wheel coupling
- Dolly (trailer)
- Road transport in Australia
- Ringfeder coupling devices
[edit] External links
- Australian Road Train Association
- Northern Territory Road Train road safety TV commercials.
- South Australian Roads road train gazette
- NSW Roads and Traffic Authority road train operators gazette
- U.S. department of Transportation, Federal Highway Administration, Chapter VII, Safety.
- The U.S. Department of Transportation's Western Uniformity Scenario Analysis.
- British Columbia Government Licensing Buletin 6
- British Columbia Government Licensing Buletin 41
