||The examples and perspective in this article deal primarily with Australia and do not represent a worldwide view of the subject. (November 2014)|
A road train, roadtrain or land train is a method of trucking used in remote areas of Argentina, Australia, Mexico, the United States, and Canada to move freight efficiently. The term "road train" is most often used in Australia. In the United States the terms "triples", "turnpike doubles", and "Rocky Mountain doubles" are commonly used for longer combination vehicles (LCVs). A road train consists of a relatively conventional tractor unit, but instead of towing one trailer or semi-trailer, a road train pulls two or more of them.
- 1 History
- 2 Usage
- 3 Trailer arrangements
- 4 Rules and regulations
- 5 World's longest road trains
- 6 See also
- 7 Notes
- 8 External links
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 nineteenth century, according to Basil Fuller in his book, "The Ghan". They displaced bullock teams for the carriage of minerals to port and were, in turn, superseded by railways.
There is an earlier road train built by its inventor in the United Kingdom. It is shown in the No. 320 (No. 8. Vol. 12, February 23, 1907) edition of "The Auto" Title: The Renard Road Train, page 242.
In the 1930/40s, the government of South Australia operated an AEC 8x8 military truck 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. With 130 hp (97 kW), the AEC was grossly underpowered by today's standards, and drivers and offsiders 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 Johansson is recognised as the inventor of the modern road train. After transporting stud bulls 200 mi (320 km) to an outback property, Johansson was challenged to build a truck to carry 100 head of cattle instead of the original load of 20. Provided with financing of a couple of thousand pounds and inspired by the tracking abilities of the Government roadtrain, Johansson began construction. Two years later his first road train was running.
Johansson's first road train consisted of a U.S. 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 last 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.
Australia has the largest and heaviest road-legal vehicles in the world, with some configurations topping out at close to 200 tonnes (197 long tons; 220 short tons). The majority are between 80 and 120 t (79 and 118 long tons; 88 and 132 short tons).
Double (two-trailer) road train combinations are allowed in most areas of Australia, and within the environs (albeit limited) 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.
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). Tasmania and Victoria do not allow the operation of roadtrains on any of their roads. Victoria had previously allowed double road trains to operate around Mildura for the vintage grape harvest.
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 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". See illustration. Sometimes, if many trailers are required to be moved at the one time, they will be triple-stacked, or "tripled-up."
Higher Mass Limits (HML) Schemes are now piloting in all jurisdiction in Australia, allowing trucks to carry additional weight.
In Canada, road trains are more commonly referred to as Long Combination Vehicles (LCVs), as Extended Length Vehicles (ELVs), or Energy Efficient Motor Vehicles (EEMVs).
Four types of LCV are permitted; turnpike doubles, triples, rocky mountain doubles, and queen city triples.
Turnpike doubles consist of a tractor unit pulling a semi-trailer (up to 53 feet (16.2 m) long). An A-type or C-type converter is connected to the rear of the trailer, and carries a second trailer. Alternatively, the lead trailer may have a hideaway fifth wheel, which enables direct coupling of the second trailer without a converter. The total permissible length is 38 m (125 ft).
Triples may be up to 35 m (115 ft) in length when using A or C converters, or 38 m (125 ft) in B-train configuration.
Rocky mountain doubles are limited to 31 m (102 ft) in overall length, but have the advantage of being legal on two-lane, undivided roads. A, B, and C-train variants are used. Other LCVs may only be used on divided highways.
Queen city triples consist of a tractor unit pulling one semi-trailer up to 53 feet (16.2 m) long and two shorter "pup" trailers up to 32 feet (9.8 m) long. Queen city triples are only permitted between the cities of Saskatoon and Regina Saskatchewan. These are the longest combinations allowed in North America on public highways.
Alberta allows LCV operation on most major highways. The Queen Elizabeth II Highway between Calgary and Edmonton carries the majority of turnpike doubles and triples. Theoretically, these vehicles could be used on Highway 16 as far west as Hinton and Highway 43 as far north as Valleyview, but are rarely used on these routes. LCV operation north and west of Edmonton is limited to rocky mountain doubles, since the road is undivided north of Valleyview. The destination of most rocky mountain doubles is Yellowknife in the Northwest Territories.
The Northwest Territories allows LCVs of up to 31 m (101.7 ft) in length. These vehicles are restricted to specific destinations in Hay River and Yellowknife. LCVs do not operate north of Yellowknife.
Licensing of LCV drivers
(Information restricted to Alberta and NWT.) Prospective LCV drivers must have held a licence for legal length articulated vehicles for two years (five years in the North West Territories.). They may have no more than two moving offences recorded within three years and may not have any vehicle-related criminal code violations. They are required to pass a PDIC (professional driver improvement course) every four years. They are required to pull an LCV at least once a year in order to keep their LCV licence.
|This section needs additional citations for verification. (May 2013)|
In the United States, trucks on public roads are limited to two trailers (two 28 ft (8.5 m) and a dolly to connect. The limit is 63 ft (19.2 m) end to end). Some states allow three 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. The term "road train" is not commonly used in the United States; "turnpike train" has been used, generally in a pejorative sense.
In Finland, Sweden, Germany, the Netherlands, Denmark, and select roads in Norway (for a period of three years commencing November 24, 2008), trucks with trailers are allowed to be 25.25 m (82.8 ft) long. 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, that is with a flat front, a high floor about 1.2 m (3.9 ft) above ground with the engine below. The Scandinavian countries are less densely populated than the rest of the EU countries and distances, especially in Finland and Sweden, are vast. Until the late 1960s, vehicle length was unlimited, giving rise to long vehicles to handle goods cost effectively. As traffic increased, 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 options up to 11-axle, 34-meter (111.5 ft) long, 82-tonne (81-long-ton; 90-short-ton) combinations, ruled out all road train type vehicles for the foreseeable future. Sweden is currently (2010) performing tests on log hauling trucks, weighing up to 90 t (89 long tons; 99 short tons) and measuring 30 meters (98.4 ft) and haulers for two 40 ft containers, measuring 32 meters (105 ft) in total.
Mexico allows LCVs consisting of double trailers around 12.5 m (41.0 ft) in length. They must display a sign reading "Precaucion: Doble Semi-remolque" (Caution: Double Semi Trailer) on the rear, indicating that a double-length trailer is in use. Mexico does not place special road restrictions on LCVs other than those already in place for conventional tractor-trailers.
Recently, regulations for road trains have been stiffened, limiting cargo to 60 tons among the two trailers. Truck drivers have felt strain due to this change because previously some commercial drivers received company incentives to accept overloading of their double trailers.
A B-double (B-Train) consists of a prime mover towing a specialised lead trailer that has a fifth-wheel mounted on the rear towing another semi-trailer, resulting in two articulation points. Around container ports in Australia there may also have what is known as a super B-double, these being a B-double that has a quad axle lead trailer capable of holding one 40-foot shipping container or two 20-foot shipping containers, and the rear trailer being capable of the same with either a tri or quad rear axle set. However, because of their large length and low accessibility into narrow streets, these vehicles are restricted in where they can go and are generally used for terminal-to-terminal work, i.e., wharf to container holding park or wharf-to-wharf. The rear axle on each trailer can also pivot slightly while turning to prevent scrubbing out the edges of the tyres due to the heavy loads placed on them.
Same as a B-double but with an additional lead trailer behind the prime mover. These are run in most states of Australia where double road trains are allowed. There is one exception to that rule: B-Triples are operated in Victoria, but by one operator, under a strict permit and on a dedicated route, between the Ford plants at Geelong and Campbellfield. Australia's National Transport Commission proposed a national framework for B-triple operations that includes basic vehicle specifications and operating conditions that the commission anticipates will replace the current state-by-state approach, which largely discourages the use of B-triples for interstate operation.
An AB triple consists of a prime mover, a semi-trailer, a converter dolly, then a B-double.
A BAB Quad consists of two B-double units linked with a converter dolly.
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 drawbars, thus eliminating the drawbar connection as an articulation point. One of the axles on a C-dolly is self-steerable to prevent tire scrubbing. C-dollies are not permitted in Australia, due to the lack of articulation.
Dog-trailer (dog trailer)
A dog-trailer (also called a pup) is any trailer that is hooked to a converter dolly, with a single A-frame drawbar that fits into the Ringfeder or pintle hook on the rear of the trailer in front, giving the whole unit three to five articulation points and very little roll stiffness.
Rules and regulations
A is a B-double.
B is a B-triple.
C is a double road train. A "Pocket road train" is similar, but with shorter trailers and dolly drawbar.
D is an AB-triple.
E is a BAB Quad.
F is an ABB Quad.
G is triple road train.
H is a 2AB Quad.
K represents the largest road trains operating in Australia and the world. Called a "Powertrain" or a "Body and six", these machines operate at the Granites gold mine in the western Northern Territory, and are used in place of 200t dump trucks, because of the distances involved on the haul run. A 600 hp (450 kW) 19 L (1,200 cu in) Cummins engine powers the prime mover, while a 400 hp (300 kW) Cummins engine is installed in the rear trailer of the B-double, driving through an automatic transmission, giving a total of 1,000 hp (750 kW). Weights of 460 t (453 long tons; 507 short tons) are achieved with ore loading in side-tipper bodies on a 100 km (62 mi) round trip. As these trucks operate on private property, they are not subject to governed weight and length rulings, but instead are used in the most efficient way possible.
Interstate Road Transport registration
In 1991 at a Special Premiers Conference, Australian Heads of Government signed an Inter-governmental Agreement to establish a national heavy vehicle registration, regulation and charging scheme, otherwise known as FIRS.
This registration scheme is known as the Federal Interstate Registration Scheme. The requirements of the scheme were as follows: If the vehicle was purchased to be used for interstate trade, no stamp duty was payable on the purchase price of the vehicle. The vehicle had to be subjected to an annual inspection for roadworthy standards, which had to be passed before registration could be renewed. With the registration identification, the first letter of the 6 digit identified the home state: W = Western Australia, S = South Australia, V = Victoria, N = New South Wales, Q = Queensland, T = Tasmania, A = Australian Capital Territory and C = Northern Territory. Due to the 'eastern' and 'western' mass limits in Australia, two different categories of registration were enacted. The second digit of the registration plate showed what mass limit was allowed for that vehicle. If a vehicle had a 'V' as the second letter, its mass limits were in line with the eastern states mass limits, which were:
- Steer axle, 1 axle, 2 tyres: 5.40 t (5.31 long tons; 5.95 short tons)
- Steer axle, 2 axles, 2 tyres per axle: Non load sharing suspension 9.00 t (8.86 long tons; 9.92 short tons)
- Load sharing suspension 10.00 t (9.84 long tons; 11.02 short tons)
- Single axle, dual tyres: 8.50 t (8.37 long tons; 9.37 short tons)
- Tandem axle, dual tyres: 15.00 t (14.76 long tons; 16.53 short tons)
- Tri axle, dual tyres or 'super single' tyres: 18.00 t (17.72 long tons; 19.84 short tons)
- Gross combination mass on a 6-axle vehicle not to exceed 38 t (37 long tons; 42 short tons)
If a vehicle had an X as the second letter, its mass limits were in line with the western states mass limits, which were:
- Steer axle, 1 axle, 2 tyres: 6.00 t (5.91 long tons; 6.61 short tons)
- Steer axle, 2 axles, 2 tyres per axle
- Non load sharing suspension 10.00 t (9.84 long tons; 11.02 short tons): Load sharing suspension 11.00 t (10.83 long tons; 12.13 short tons)
- Single axle, dual tyres: 9.00 t (8.86 long tons; 9.92 short tons)
- Tandem axle, dual tyres: 16.50 t (16.24 long tons; 18.19 short tons)
- Tri axle, dual tyres or "super single" tyres: 20.00 t (19.68 long tons; 22.05 short tons)
- Gross combination mass on a 6-axle vehicle not to exceed 42.50 t (41.83 long tons; 46.85 short tons)
If the second digit of the registration was a T, that designated a trailer. One of the main criteria of the registration was that intrastate operation was not permitted. The load had to come from one state and be delivered to another state or territory. Many grain carriers were reported and prosecuted for cartage from the paddock to the silos. If, though, they went to a port silo, they were given the benefit of the doubt, as that grain was more than likely going overseas.
Australian road trains have horizontal signs front and back with 180 mm (7.1 in) high black uppercase letters on a reflective yellow background reading "ROAD TRAIN". The sign(s) must have a black border and be at least 1.02 m (3.3 ft) long and 220 mm (8.7 in) high and be placed between 500 mm (19.7 in) and 1.8 m (5.9 ft) above the ground on the fore or rearmost surface of the unit.
In the case of B-Triples in Western Australia they are signed front and rear with "Road-Train" until they cross the WA/SA border where they are then signed with "Long Vehicle" in the front and rear.
Converter dollys must have a sign affixed horizontally to the rearmost point, complying to the same conditions, reading "LONG VEHICLE". This is required for when a dolly is towed behind a trailer.
- B-Double- 27.5 m (90.2 ft) max.
- B-Triple- 33.5 m (110 ft) max.
- Pocket road train- 27.5 m (90.2 ft) max. This configuration is classed as a "Long Vehicle".
- Double road train- 36.5 m (120 ft) max.
- Triple and AB-Quad road trains- 53.5 m (176 ft) max.
Operational weights are based on axle group masses, as follows:
- Single axle (Steer tyre)- 6.0 t (5.9 long tons; 6.6 short tons)
- Single axle (Steer axle with 'super single' tyres) 6.7 t (6.6 long tons; 7.4 short tons)
- Single axle (dual tyres) - 9.0 t (8.9 long tons; 9.9 short tons)
- Tandem axle grouping- 16.5 t (16.2 long tons; 18.2 short tons)
- Tri axle grouping- 20.0 t (19.7 long tons; 22.0 short tons)
Therefore, a B-Double would weigh 62.5 t (61.5 long tons; 68.9 short tons) (6 t or 5.9 long tons or 6.6 short tons + 16.5 t or 16.2 long tons or 18.2 short tons + 20 t or 20 long tons or 22 short tons + 20 t or 20 long tons or 22 short tons). A double road train would have an operational weight (without concessions) of 79 t (78 long tons; 87 short tons) (6 t or 5.9 long tons or 6.6 short tons + 16.5 t or 16.2 long tons or 18.2 short tons + 20 t or 20 long tons or 22 short tons + 16.5 t or 16.2 long tons or 18.2 short tons + 20 t or 20 long tons or 22 short tons). A triple is 79 t (78 long tons; 87 short tons) + 36.5 t (35.9 long tons; 40.2 short tons) (16.5 t or 16.2 long tons or 18.2 short tons + 20 t or 20 long tons or 22 short tons), giving an all up weight of 115.5 t (113.68 long tons; 127.32 short tons). Quads weigh in at 135.5 t (133.4 long tons; 149.4 short tons). Concessional weight additions (0.5–2.5 t or 0.49–2.46 long tons or 0.55–2.76 short tons per group) can see a quad end up weighing 149 t (147 long tons; 164 short tons). If a tri-drive prime mover is utilised, along with tri-axle dollys, weights can reach nearly 170 t (167 long tons; 187 short tons).
The Australian national heavy vehicle speed limit is 100 km/h (62 mph), excepting:
- NSW, Queensland and South Australia, where the speed limit for any road train is 90 km/h (56 mph).
In western Canada, LCVs are restricted to 100 km/h (62 mph), or the posted speed limit. Trucks of legal length (<25 metres or 82 feet) may travel at 110 km/h (68 mph), or the posted speed limit.
World's longest road trains
Below is a list of longest road trains driven in the world. Most of these had no practical use, as they were put together and driven across relatively short distances for the express purpose of record-breaking.
- In 1989, a trucker named "Buddo" tugged 12 trailers down the main street of Winton, Queensland.
- In 1993, "Plugger" Bowden took the record with a 525 hp (391 kW) Mack SuperLiner pulling 16 trailers, but a few months later this effort was surpassed by Darwin driver Malcolm Chisholm with a 290 tonnes (285 long tons; 320 short tons), 21 trailer rig extending 315 metres (1,033 ft).
- There was some back and forth in the 1990s between Winton and Bourke, New South Wales, with the record finishing in Winton with 34 trailers.
- In 1999, the town of Merredin, Western Australia officially 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 t (593 long tons; 665 short tons) and measuring 610 m (2,001 ft) were pulled by a Kenworth 10x6 K100G for 8 km (5 mi).
- On October 19, 2000, Doug Gould set the first of his records at Kalgoorlie, Western Australia, when a roadtrain made up of 79 trailers, measuring 1,018.2 m (3,341 ft) and weighing 1,072.3 t (1,055.4 long tons; 1,182.0 short tons), was pulled by a Kenworth C501T driven by Steven Matthews a distance of 8 km (5 mi).
- On March 29, 2003, the record was surpassed near Mungindi, New South Wales, by a road train consisting of 87 trailers and a single prime mover (measuring 1,235.3 m (4,053 ft) in length).
- The record returned to Kalgoorlie, Western Australia, on October 17, 2004, when Doug Gould assembled 117 trailers for a total length of 1,445 m (4,741 ft). The record nearly didn't fall, as the first prime mover's main driveshaft broke when taking off. A second truck was quickly made available, and pulled the train a distance of 1,500 m (4,921 ft).
- In 2004, the record was again broken by a group from Clifton, Queensland which used a standard Mack truck to pull 120 trailers a distance of about 100 metres (328 ft).
- On February 18, 2006, an Australian built Mack truck with 112 semi-trailers, 1,300 t (1,279 long tons; 1,433 short tons) and 1,474.3 metres (4,836 ft 11 in) long, pulled the load 100 metres (328 feet) to recapture the record for the longest road train (multiple loaded trailers) ever pulled with a single prime mover. It was on the main road of Clifton, Queensland, that 70-year-old John Atkinson claimed a new record, pulled by a tri-drive Mack Titan.
- Air brake (road vehicle)
- Dolly (trailer)
- Fifth wheel coupling
- Gladhand connector
- Longer Heavier Vehicle
- Overland train
- Ringfeder coupling devices
- Road transport in Australia
- Rolling highway – freight trucks by rail
- Semi-trailer truck – large trucks such as road trains and articulated lorries
- Long Combination Vehicle
- States that Allow Longer Combination Vehicles
- Beavan, Arthur H. (1903). Tube, Train, Tram, and Car or Up-to-date Locomotion. London: G. Routledge & sons. p. 217.
- Layriz, Otfrie; Marston, Robert Bright (1900). Mechanical traction in war for road transport, with notes on automobiles generally. London: S. Low, Marston and Company. p. 20.
- The Illustrated war news. 29 November 1916.
- Wyatt, Horace Matthew (1914). Motor transports in war. Hodder and Stoughton. pp. 43–44.
- View From The North - Episode Four: Roads North
- BBC Worldwide Limited, Jeremy Clarkson's Motorworld, Australian episode
- Hema Maps (Firm) & Martin, Ray. & Martin, Will. (2007), Australia truckies atlas [cartographic material] : the complete atlas for the professional driver / Hema Maps ; [cartography, Ray Martin and Will Martin] - ISBN 978-1-86500-426-6 ISBN 1-865004-26-X - has state by state routes and route restrictions I
- "Truck Driver's Guide Book"
- Fact #411: February 13, 2006 States that Allow Longer Combination Vehicles U.S. Department of Energy - Energy Efficiency and Renewable Energy Vehicle Technologies Office http://www1.eere.energy.gov/vehiclesandfuels/facts/2006_fcvt_fotw411.html
- "Gangway! Here comes a turnpike train!", The Times-News (Hendersonville, N.C.), Nov. 30, 1960, p. 7.
- Press release from the office of the Secretary of Transportation
- The next environmental improvement - Long truck rigs Volvo Trucks Magazine 2008-10-03
- Article in local news paper
- COAG backs B-triple network, ntc.gov.au
- Rail Geelong - Locations : Ford Siding, railgeelong.com
- Clay Lucas, "Victorian councils want no truck with B-triple monsters", October 20, 2008, theage.com.au
- Safety fears over B-triple truck plan, August 8, 2008, Geelong Advertiser.
- Bereni, Matthieu; Rob Di Cristoforo (2012). "Connecting Australia with Modular B-Triples". Transportation Research Record (Washington, D.C.: Transportation Research Board of the National Academies) (2288): 57–65. doi:10.3141/2288-07.
- Interstate Road Transport Charge Amendment Bill 1998 (Bills Digest 192 1997-98)
- Doug's Tug, the pick & shovel (13), December 2000.
- The Truck Pull : The World's Longest Road Train, marleystransport.com
- World records : Preparations for the Big Attempt, gouldtransport.com.au, quoted from The Kalgoorlie Miner, Friday November 10, 2000.
- TALKIN' TITAN TOUGH, November 21, 2005, macktrucks.com.au
- Monster Update : ROAD TRAIN RECORD Fleet Watch,
- Former road train record holder may take on new challenge, 22 february 2006, ABC News online,
- Australia's New World Record Road Train Pull, thedieselgypsy.com
- Qld truck driver sets world's longest road train record, February 19, 2006, ABC News.
- Bulldog Reclaims Record Down Under, macktrucks.com
|Wikimedia Commons has media related to Road trains.|
- Australian Road Train Association
- Australian National Heavy Vehicles Accreditation Scheme.
- Northern Territory Road Train road safety TV commercials.
- South Australian Roads road train gazette
- NSW Roads and Traffic Authority road train operators gazette
- NSW Roads and Traffic Authority Restricted Access Vehicles route map index
- NSW Roads and Traffic Authority Reflective sign standards
- 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
- Roadmap of technologies able to halve energy use per passenger mile includes the dynamically coupled, heterogeneous type of roadtrain
- Road trains and electrification of transport