History

Early road trains consisted of traction engines pulling multiple wagons. The first identified road trains operated into South Australia's Flinders Ranges from the Port Augusta area in the mid-19th century. They displaced bullock teams for the carriage of minerals to port and were, in turn, superseded by railways.

During the Crimean War, a traction engine was used to pull multiple open trucks.[3] By 1898 steam traction engine trains with up to four wagons were employed in military manoeuvres in England.

In 1900, John Fowler & Co. provided armoured road trains for use by the British Armed Forces in the Second Boer War. Lord Kitchener stated that he had around 45 steam road trains at his disposal.

A road train devised by Captain Charles Renard of the French Engineering Corps was displayed at the 1903 Paris Salon. After his death, Daimler, which had acquired the rights, attempted to market it in the United Kingdom. Four of these vehicles were successfully delivered to Queensland, Australia, before the company ceased production upon the start of World War I.

In the 1930s/40s, the government of Australia operated an AEC Roadtrain to transport freight and supplies into the Northern Territory, replacing the Afghan camel trains that had been trekking through the deserts since the late 19th century. This truck pulled two or three 6 m (19 ft 8 in) Dyson four-axle self-tracking trailers. At 130 hp (97 kW), the AEC was grossly underpowered by today's standards, and drivers and offsiders (a partner or assistant) routinely froze in winter and sweltered in summer due to the truck's open cab design and the position of the engine radiator, with its 1.5 m (4 ft 11 in) cooling fan, behind the seats.

Australian Kurt Johannsen, a bush mechanic, is recognised as the inventor of the modern road train. After transporting stud bulls 200 mi (320 km) to an outback property, Johannsen was challenged to build a truck to carry 100 head of cattle instead of the original load of 20. Provided with financing of about 2000 pounds and inspired by the tracking abilities of the Government roadtrain, Johannsen began construction. Two years later his first road train was running.

Johannsen's first road train consisted of a United States Army World War II surplus Diamond-T tank carrier, nicknamed "Bertha", and two home-built self-tracking trailers. Both wheel sets on each trailer could steer, and therefore could negotiate the tight and narrow tracks and creek crossings that existed throughout Central Australia in the earlier part of the 20th century. Freighter Trailers in Australia viewed this improved invention and went on to build self-tracking trailers for Kurt and other customers, and went on to become innovators in transport machinery for Australia.

This first example of the modern road train, along with the AEC Government Roadtrain, forms part of the huge collection at the National Road Transport Hall of Fame in Alice Springs, Northern Territory.

In 2023, Janus launched the first BEV triple road train with 620 kWh battery, also the world's heaviest street-legal BEV truck at 170 tonnes (gross weight).

Usage

Australia

A four-trailer road train in the Australian outback with a Volvo NH15 prime mover

The term road train is used in Australia. In contrast with a more common semi-trailer towing one trailer or semi-trailer, the diesel prime mover of a road train hauls two or more trailers or semi-trailers. Australia has the longest and heaviest road-legal road trains in the world, weighing up to 200 tonnes (197 long tons; 220 short tons).

Double (two-trailer) road train combinations are allowed on some roads in most states of Australia, including specified approaches to the ports and industrial areas of Adelaide, South Australia and Perth, Western Australia. A double road train should not be confused with a B-double, which is allowed access to most of the country and in all major cities.

In South Australia, B-triples up to 35.0 metres (114 ft 10 in) and two-trailer road trains to 36.5 metres (119 ft 9 in) were only permitted to travel on a small number of approved routes in the north and west of the state, including access to Adelaide's north-western suburban industrial and export areas such as Port Adelaide, Gillman and Outer Harbour via Salisbury Highway, Port Wakefield Road and Augusta Highway before 2017. A project named Improving Road Transport for the Agriculture Industry added 7,200 kilometres (4,500 mi) of key routes permitted to operate vehicles over 30 m (98 ft 5 in) in 2015–2018.[

Triple road train near Normanton, Queensland

Triple (three-trailer) road trains 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 (B double with two additional trailers coupled behind). Darwin is the only capital city in the world where triples and quads are allowed to within 1 km (0.62 mi) of the central business district (CBD).

Strict regulations regarding licensing, registration, weights, and experience apply to all operators of road trains throughout Australia.

Road trains are used for transporting all manner of materials: common examples are livestock, fuel, mineral ores, and general freight. Their cost-effective transport has played a significant part in the economic development of remote areas; some communities are totally reliant on regular service.

When road trains get close to populated areas, the multiple dog-trailers are unhooked, the dollies removed and then connected individually to multiple trucks at "assembly" yards.

When the flat-top trailers of a road train need to be transported empty, 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 one time, they will be triple-stacked, or "tripled-up".

Higher Mass Limits (HML) Schemes are now in all jurisdictions in Australia, allowing trucks to carry additional weight beyond general mass limits. Some roads in some states regularly allowing up to 4 trailers at 53.5 metres (175 ft 6 in) long and 136 tonnes (134 long tons; 150 short tons).[17] On private property like mines, highway restrictions on trailer length, weight and count may not apply. Some of the heaviest road trains carrying ore are multiple unit with a diesel engine in each trailer, controlled by the tractor.

Diesel sales in Australia (per year) are around 32 billion litres, of which some is used by road trains. In order to reduce emssions and running cost, trials are made with road trains powered by batteries.

United States

See also: Federal Bridge Gross Weight Formula

Permitted routes for longer combination vehicles on the U.S. National Highway System: 2017

In the United States, trucks on public roads are limited to two trailers (two 28 ft or 8.5 m and a dolly to connect; the limit is 63 ft or 19 m end to end). Some states allow three 28 ft or 8.5 m trailers, although triples are usually restricted to less populous states such as Idaho, Oregon, and Montana, plus the Ohio Turnpike and Indiana East–West Toll Road. 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 hauling in the interior west (such as ore or aggregate). Triples are sometimes marked with "LONG LOAD" banners both front and rear. "Turnpike doubles"—tractors towing two full-length trailers—are allowed on the New York Thruway and Massachusetts Turnpike (Interstate 90), Florida's Turnpike, Kansas Turnpike (Kansas City - Wichita route) as well as the Ohio and Indiana toll roads. Colorado allows what are known as "Rocky Mountain Doubles" which is one full length 53 ft or 16 m trailer and an additional 28 ft or 8.5 m trailer. The term "road train" is not commonly used in the United States; "turnpike train" has been used, generally in a pejorative sense.

STAA double pup 28.5 foot trailers

In the western United States LCVs are allowed on many Interstate highways. The only LCVs allowed nationwide are STAA doubles.

On private property like farms, highway restrictions on trailer length and count do not apply. Bales of straw, for example, are sometimes moved in wagon trains of up to 20 trailers an eighth of a mile long (carrying a total of 3,600 bales).

Europe

Timber being unloaded from a B-double at Pellets Asturias, Spain

In Finland, Sweden, Germany, the Netherlands, Denmark, Belgium, and some roads in Norway, trucks with trailers are allowed to be 25.25 m (82.8 ft) long. In Finland, a length of 34.5 metres (113 ft) has been allowed since January 2019. In Sweden, this length is allowed on several major roads, including all of E4, since August 2023. 34.5 meters allows two 40 foot containers.

Elsewhere in the European Union, the limit is 18.75 m (61.5 ft) (Norway 19.5 m or 64 ft). The trucks are of a cab-over-engine design, with a flat front and a high floor, about 1.2 m (3.9 ft) above ground. The Scandinavian countries are less densely populated than the other EU countries, and distances, especially in Finland and Sweden, are long. Until the late 1960s, vehicle length was unlimited, giving rise to long vehicles to cost effectively handle goods. As traffic increased, truck lengths became more of a concern and they were limited, albeit at a more generous level than in the rest of Europe.

In the United Kingdom in 2009, a two-year desk study of Longer Heavier Vehicles (LHVs), including up to 11-axle, 34-metre (111.5 ft) long, 82-tonne (81-long-ton; 90-short-ton) combinations, ruled out all road-train-type vehicles for the foreseeable future.

40 foot container turnpike double

In 2010, Sweden was performing tests on log-hauling trucks, weighing up to 90 t (89 long tons; 99 short tons) and measuring 30 metres (98.4 ft) and haulers for two 40 ft containers, measuring 32 metres (105 ft) in total. In 2015, a pilot began in Finland to test a 104-tonne timber lorry which was 33 metres (108 ft) and had 13 axles. Testing of the special lorry was limited to a predefined route in northern Finland

Since 2015, Spain has permitted B-doubles with a length of up to 25.25 metres (82.8 ft) and weighing up to 60 tonnes to travel on certain routes.

In 2020, a small number of road trains were operating between Belgium and the Netherlands.

Mexico

In Mexico road trains exist in a limited capacity due to the sizes of roads in its larger cities, and they are only allowed to pull 2 trailers joined with a pup or dolly created for this purpose. Recently the regulations tend to be more severe and strict to avoid overloading and accidents, to adhere to the federal rules of transportation. Truck drivers must obtain a certificate to certify that the driver is capable to manipulate and drive that type of vehicle.

All the tractor vehicles that make road train type transport in the country (along with the normal security requirements) need to have visual warnings like;

• "Precaución Doble Semirremolque" alert (Warning Double Semi-Trailer) located in the frontal fenders of the tractor and in the rear part of each trailer,

• yellow turn and warning lights to be more visible to other drivers,

• a seal for the entire vehicle approving the use as double semi trailer,

• federal license plates in every trailer, dolly, and tractor unit.

Some major cargo enterprises in the country use this form to cut costs of carrying all type of goods in some regions where another form of transportation are so expensive to improve it due to the difficult geography of the country.

The Mexican road train equivalent form in Australian Standard is the A-Double form, the difference is that the Mexican road trains can be hauled with a long distance tractor truck.

Zimbabwe

In Zimbabwe, they are only used in one highway, Ngezi - Makwiro road. They make use of 42 m long road trains pulling three trailers.