Working Vehicles

Why Australian heavy trucks are the way they are


In Europe, the USA and Japan, very few people notice the fundamental differences between each country’s trucks. It’s only in Australia, where all three nations’ trucks compete that the differences are so obvious. “Why is it so?”, the good professor used to ask and Allan Whiting makes an attempt at explanation.


The reason why heavy trucks vary in shape and size in different in parts of the world is all down to regulations. These regulations were born out of necessity to make trucks work within and between population centres.

Global regulations are as varied as the countries in which they were created, but all of them date from the post Word War Two period. At that time, truck traffic increased exponentially and regulations were necessary to maintain some sort of order.

Because most cities and towns were designed before heavy vehicles existed, length regulations were necessary to make sure trucks and trailers could ‘fit’. Also axle-weight regulations were necessary to prevent road and bridge damage. 




European truck before length regulations


Truck-spotters from Oz who land in any European country are starved of bonneted trucks to ogle, because there are hardly any.  The reason is simple: Europe has a regulated 16.5-metre overall length for a semi trailer and prime mover combination and 18.75 metres for a rigid truck pulling a ‘dog’ or ‘pig’ trailer. With such tight length laws it’s not economically possible to devote any of that length to a bonnet: that length is need for trailer or body capacity.


Compact Euro truck and pig trailer


While Europe’s length laws are restrictive, its axle weight laws are liberal: steer axles typically rated at 7.5 tonnes; a single drive axle at 11.5 tonnes and a wide-single-tyred tri-axle, 24 tonnes. Permissible gross combination masses (GCMs) are 40-44 tonnes.

Also critical is the so-called ‘bridge formula’ dimension that specifies the minimum length between the steer axle and the rear trailer axle and between drive and lead trailer axles. Those dimensions are in place to ensure ‘spread’ loading on bridges. Europe’s bridge formula distances are much shorter than those in Australia or the USA, allowing more compact semi rigs.


Typical long-distance Euro semi combination


So, the typical International transport (TIR) combination in Europe is a single-drive cab-over-engine (COE) prime mover, pulling a 12-metre tri-axle trailer with that tri well forward along the trailer length. This combination is much more manoeuvrable than Australian or US semi combinations, letting it turn in narrow, cobbled streets and back into tight docks and laneways.

(I’ve passed the Mercedes-Benz advanced driver test in Germany and it’s amazing where you get taught to take these nimble five-axle rigs.)




Peterbilt 1960 COE and dog trailer


Popping into the USA is a more familiar truck-spotting exercise for us Aussies. Over there, legal axle weights are lower and bridge formula dimensions are greater – as in Australia – so semi-trailer rigs are longer and lighter than European ones.

However, there’s a distinctly North American twist to the US regulations that do not specify maximum overall length. However, it wasn’t always like that.

After Word War Two there were overall length regulations in place – 55 feet, with maximum trailer length of 45 feet. That forced truck makers to build high-set ‘bubblenose’ prime movers, with 94-inch bumper to back of cab dimensions. That changed to COE cabs after White popularised the already-invented tilt-cab in 1950.


‘Bubblenose’ Freightliner and dog trailer


The length situation changed in 1956, under the direction of President Eisenhower, who had been impressed by the German autobahn system and replicated it in the USA. Being federally-funded and maintained, this Interstate Network use was subject to restrictive regulations, to ensure longevity.

Maximum GCM on the Interstates was initially set, in 1956, at 73,280 pounds (33,240kg). After experience with the network the permissible GCM was raised to 80,000 pounds (36,300kg) in 1970 and that’s where it sits today. 

At the same time, trailer and semi-trailer lengths were governed, but, for the first time anywhere in the world, prime mover length was not. Also, the national rules that applied on the Interstate Highway network were not applicable on State-built roads, so non-interstate trucks can be much longer and heavier.


Typical US Interstate ’18-wheeler’


The typical US ‘Interstate-18-wheeler’ semi-trailer rig has tandem drive and a tandem-axle trailer that can be up to 53 feet (16.5 metres) in length. Despite the lower GCM compared with Europe’s, tandem drive is necessary to spread drive axle load and the trailer tandem is far aft, to comply with bridge formula restrictions.

On top of that ‘enforced lengthening’ , prime mover length is unrestricted and that has led to legendary bonnet, wheelbase and sleeper-cab lengths!

Manoeuvring a US semi-trailer needs more wide open space than European rigs need.




Japanese rigid truck 6×2


The other major source of trucks in the Australian market is Japan.

Because Japan is made up of small, mountainous islands, it has relied traditionally on sea freight and still does. AIso, rail freight is highly developed. Truck transport is vital, but not in a bulk, linehaul way.

There are relatively few semi-trailer vehicles on Japanese roads and those that are, carry mainly indivisible loads. Prime movers are mostly single drive and trailers are tandem or tri-axle, with a maximum GCM of 36 tonnes. Most heavy truck traffic is in the form of rigid three- and four-axle trucks that are restricted to 20-25 tonnes gross vehicle mass (GVM).


Japanese 8×4 rigid volume body truck with 19.5-inch wheels


That makes it easy to understand why the strength of Japanese trucks in the Australian market has been with rigid trucks. It took many years for the Japanese makers to come up with higher-torque prime movers, because there is no major need for them in Japan.




The Poms and the Yanks duelled for Aussie truck business


The history of Australia heavy truck transport is one of adaptation. After the War, we made do with what was available and British trucks were a common and patriotic choice.

However, British trucks were designed with Europe in mind, not the Colonies. They had unbreakable back axles and chassis, but their engines hated running at high revs to achieve modest road speeds.

German trucks had made a positive impression Down Under before the War and resumed business after hostilities ceased. The Mercedes-Benz 1418 became a legend.


The 1418 was one of the last bonneted Euro prime movers


The main North American truck maker in the Australian market, before and in the post-War years, was International Harvester, which led the market for many years with local ACCO-derived models and Australianised US products.

The Japanese became a major trading partner in the 1960s and their trucks made their way Down Under in the 1970s.

The fact that British, European, North American and Japanese trucks showed they could compete in the Australian heavy truck market soon prompted fresh entrants and, by the late 1980s, we had all major global brands on sale in the relatively small Australian heavy truck market.


No good in Melbourne, eh?


Until the late 1970s, Australian road transport rules and regulations were a mishmash of individual state and territory requirements. Because the Commonwealth of Australia Constitution Act did not specify federal control over road transport, it effectively relinquished full jurisdiction of that area to the States.

In 1952, truck drivers were frustrated by the levies on interstate road transport, which were designed to protect the state-owned railways. The drivers placed a copy of the constitution in a wheelbarrow and pushed it by hand between Melbourne and Sydney. This journey took 11 days and that was two days quicker than a parcel mailed at the same time that was carried by rail.

Their purpose was to challenge the validity of the New South Wales State Transport Act against Section 92 of the Constitution, which provided that trade, commerce and intercourse between the States ‘shall be absolutely free’. Known as the Hughes & Vale case, it eventually led a successful constitutional challenge in the High Court that opened-up interstate road transport.

Hughes & Vale was a significant turning point for the transport industry in Australia. It was the catalyst for the growth of interstate road transport, which in turn highlighted the limitations of having different road transport regulations between states and territories.


Typical ‘spread-bogie’ trailer – Historic Commercial Vehicle Club


Before 1978, interstate haulers had to calculate a ‘best fit’ combination that could traverse borders. The ‘fly in the ointment’ was invariably Victoria that imposed the strictest weight and bridge formula rules. The ‘best fit’ semi combination at one time was a single-drive prime mover, coupled to a tandem-axle, ‘spread-bogie’ trailer and that was rated at 32 tonnes GCM. 

The required spread between the two trailer axles varied, depending on the load on them, but typically was nine feet, one inch. However, I can remember operators with sliding suspensions on their trailers, so they could extend that spread to 11 fleet, one inch.

The NSW authorities knew that spread bogies were doing road damage, apart from damage to the trailers themselves, caused by excessive ’drag’ when cornering. The regulators proved it conclusively with a demo done at East Coast Transport’s depot, where a closed-bogie trailer, a spread-bogie trailer and a tri-axle trailer were driven around a set course. The tri behaved much better than the tandems, so the die was cast.

The National Association of Australian State Road Authorities (NAASRA)’ report in 1978 recommended a uniform interstate configuration that consisted of a tandem-drive prime mover, coupled to a tri-axle trailer, rated at 36 tonnes GCM. The front axle rating was 5.4 tonnes; 15 tonnes on the tandem and 18 tonnes on the tri.

Eventually, that was accepted nationally, with some increases in SA and WA that were gradually applied nationally. However, there was still a restrictive bridge formula in place and that favoured prime movers with set-forward front axles.


Forward axle configurations gave the Yanks an edge for years


North American sourced prime movers had no trouble with that bridge formula, because it was similar to the US regulations, but European trucks with long front springs and long overhangs were at a disadvantage.

I was working at Volvo Trucks Australia in the early 1970s and can remember Max Winkless, whose background was with the Antill Ranger transport business, telling the Swedes that the F88 was not optimised for Australia. The Swedes agreed to reset the front end, which is why Australia got the G88, with what was called a ‘fully-forward front axle’ (FFA). It was the same with first N-Series Volvos that also had forward-set front axles.

Mercedes-Benz didn’t change its trucks for the Aussie market and paid the price in sales, for many years. Where Volvo fitted Rockwell tandem drives as stop-gaps until it developed a lightweight tandem drive, ‘Benz stuck with its heavy-duty hub-reductions that were great for heavy haulage, but not ideal for highway work. (‘Benz also adopted short-stroke V6, V8 and V10 diesels that were ideal for Europe, but no good here.)

Scania and MAN also suffered from the front overhang issue, until the bridge formula dimensions were relaxed in the 1990s.

However, the Europeans weren’t the only companies who had to modify their trucks for Australian conditions, because the Yanks soon found out that ultra-light aluminium cabs and chassis rails just didn’t last Down Under. 

Kenworth bit the bullet early on and set up a factory to build local-spec’ trucks.

That move also came in handy when B-Doubles were allowed in Australia in 1984. 


Kenworth’s K was ideal for B-Doubles


Cab-over-engine (COE) prime movers were essential for the original 23-metre B-Double rigs and the bridge formula favoured set-forward front axles. By that time, the K100 had virtually disappeared from the North American market, so the fact that Kenworth could build a forward-axle COE in Australia, independent of its Seattle parent, gave it the bulk of the early B-Double business.

Eventually, the bridge formula dimension was relaxed and set-back axle prime movers could compete, so KW put in longer front springs and set the steer axle back! When 25-metre and 26-metre B-Doubles were allowed, bonneted prime movers could compete once more.


Canadian B-Train with tri-axle centre group


Incidentally, our B-Doubles aren’t Aussie inventions, but are based on Canadian B-Trains. Like those combinations, the original Australian units had equal length front and back trailers, with a tri-axle in the middle and a tandem at the back.

(At one press function in the 1980s, journos from trucking publications were urged to call the new combinations ‘B-Doubles’ not ‘B-Trains’, because the pollies didn’t want the public getting the idea that there were road trains running on the Eastern seaboard. The habit persists with so-called ‘A-Doubles’ that are Type One road trains with short drawbars.)


Early Australian B-Double with the same groups as a B-Train


An issue with North American bonneted trucks has always been the conversion to right hand drive. Because US engines are predominantly designed for left-hand-drive installations, the turbo and exhaust system is located on the right hand side of the engine, facing forward. Juggling steering boxes and shafts has caused plenty of problems.

The Japanese were initially happy to concentrate on the rigid-truck market, which was their strength, given the absence of high-speed linehaul semis in Japan. Their products were well made, well finished and boringly reliable, except for the trucks they specified for long-distance haulage. All these initial efforts, by all Japanese makers, ended in disaster.

Fuso prime movers blew up so frequently that they were nicknamed ‘Fuses’, forcing Mitsubishi to drop the brand name in favour of ‘Mitsubishi’ for many years. ‘Fuso’ in Australia re-emerged only in the 21st Century, after Daimler bought out Mitsubishi’s truck business.

UD was the most persistent of the Japanese, even installing Cummins engines into its CWA models. Market leader, Isuzu, tried for linehaul honours with various iterations of the Giga truck that never sold in large numbers.

Fuso and UD have figured larger in the longer-haul business since take-over by European owners, who’ve installed proved linehaul engines in these trucks.

There’s a lot more to tell about the history of post-War heavy trucks Down Under, but that’ll do for starters…


Current B-Double Down Under






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