History of Road Tankers that are Capable of Doing ‘Return Loads’

Road tankers that could haul bulk liquid one way and then haul dry freight as ‘return loads’ were first conceived of; built; and put into transport operations in the 1950’s – with the first of these known designs coming out in Canada.

The driving force behind these ‘unconventional road tanker designs’ was to get fuel (mainly diesel for logging operations and fuel oil for heating) economically transported up to the northern regions of Ontario, Alberta and British Columbia, and then to economically do ‘return loads’ to the southern areas of Canada and the northern states in the US.

These ‘return loads’ to the south were mainly sawn lumber, used in housing construction, and other wood and paper products.

From March 1993 two road tanker manufacturers in Canada were offering designs that could do return loads : Hutchinson Industries of North York, Ontario, and Advance Engineered Products of Regina, Saskatchewan.

On the ‘other side of the pond’ from the 1960’s we see that Saalasti Oy of Finland had been manufacturing their Mepa tankers for scores of operators in Scandinavia (Norway, Sweden, Denmark, Finland) and also Russia.

Then by 1993 Saalasti Oy’s Mepa designs were being made under licence in Australia and South Africa.

Saalasti Oy was principally a rail equipment and wood industry equipment manufacturer, but also designed and manufactured road tankers that could transport ‘return loads.’

Mepa tankers to transport return loads were the only road products manufactured by Saalasti Oy.

Saalasti Oy stayed out of the standard road tanker market altogether – preferring to supply their niche trailers only.

Saalasti Oy by the 1990’s had produced several hundred Mepa products, many of which were designed to transport resins for the wood industry and then transport finished wood and paper products as the return loads.

By October 1993 a project team in South Africa had independently come up with their own concept design which turned out to be similar to what had been used by Saalasti Oy for decades.

Like Saalasti Oy with their Mepa designs the South African team were fixated with the idea of putting dry cargo on top of fuel tanks.

They had started designing what arguably turned out to be the most sophisticated vehicle of its kind in the world at that time – the DualHauler.

DualHauler had been designed in to be manufactured in aluminium right down to its chassis rails to keep the tare mass of the vehicle to a minimum and to maximize its payload.

All previous road tankers that could do return loads had been manufactured with either carbon steel or stainless steel tanks and all previous road tankers of this kind had carbon steel chassis members.

The DualHauler project was a collaboration between Peter Bennetto who was a transport operator with an obsession for transport economics, and Cargo Carriers, a listed transport operator listed on the Johannesburg Stock Exchange.

Patents for DualHauler were filed in the name of Peter Bennetto (as the inventor), Garth Bolton (Cargo Carriers CEO) and Dick Garzancich (MD of Transport & Engineering Equipment - where the prototype unit was built.)

It was agreed that Cargo Carriers would be the sole operator of the vehicle in the Southern African countries where Cargo Carriers operated contracts (South Africa, Swaziland, Namibia, Zambia etc.) Around R 9.8 million / US $ 1.3 million was spent on the engineering and testing of the vehicle between 1993 and 1996.

It made no sense to supply the DualHauler product to the open market in Southern African countries where competitors would then have an equal operational advantage with Cargo Carriers.

All DualHaulers built to South Africa specifications were operated by Cargo Carriers.

Shortcomings of Designs in Operation by 2009


At the time ReturnHauler was conceived in May 2009 there were a number of design difficulties associated with tankers that could do return loads.

Deck Height

The decks of these kinds of road tankers tended to be high at around 2 200 mm.

This compared to standard flatbed trailers with deck heights of 1 500 mm.

This made the vehicles difficult for forklift operators to access in order to load and offload dry freight.

The deck height – being higher than an average height man - made these vehicles difficult to tarp up.

Return loads proved to be more difficult to check and adjust on route.

The centre of gravity of these vehicles when loaded with ‘return loads’ was around 700 mm higher than standard flatbed trailers.

This made these vehicles less stable than standard flatbed trailers, and a more cautious driving technique was required on these vehicles.

Cost of Manufacture

The monocoque construction of these pre-2009 designs made these tankers expensive to manufacture.

A useful measure of cost was to index these vehicles against their standard road tanker equivalents.

How much more expensive were they to make ?

How would potential road tanker purchasers in international markets respond to the resultant prices ?

DualHauler was clearly the most costly vehicle of its kind to date to build – due to its all-aluminium construction and due to the complex rolling and bending operations required to manufacture certain of the aluminium components; and then due to the slow and expensive TIG welding that was required in many areas of its construction.

If a standard tanker was the base cost index of 1.0; then DualHauler was 1.9.

DualHauler cost almost twice as much as a standard tanker.

The truck tractor for DualHauler cost no more than a truck tractor for a standard tanker – so the overall capital difference for the truck and DualHauler trailer combination came out at around “50% more” in total when compared to a standard road tanker combination.

Despite this on-cost, DualHauler’s price was justified if it could be operated with return loads which could amortize the capital premium.

But this said there was an adverse reaction to the high price of DualHauler where corporate customers felt they could purchase two standard tankers in place of a single DualHauler and this became the main ‘mantra’ and a reason not to want these vehicles in their fleets.

Despite the grumbling from line managers, DualHaulers were put in Cargo Carriers fleets in Durban, Cape Town, Alrode, Sasolburg, Matsapha and were put to work.

Cargo Carriers had a positive response from Trimac Transportation of Calgary, Alberta, Canada, on DualHaulers in 1996. Trimac had a fleet of 4 600 road tankers at that time and was the biggest known road tanker fleet at that time. Despite a price premium existing on DualHaulers, Trimac ordered 24 units for their Canadian operations.

ADR Compliance

By 2004 in 38 EU countries and by 2007 in South Africa (to name just 39 countries) road tankers needed to comply with revised ADR (Agreement for the Transport of Dangerous Goods) Codes.

Road tankers hereon needed to have certain minimum radii that then disallowed the ‘squarish’ tanks with sharp radii that had been used in Mepa and DualHauler designs and construction.

These vehicles stopped being legal and could no longer be manufactured legally to transport ‘dangerous goods’ which included fuel, and other UN-designated dangerous goods which included wood resins.

All ‘return loading’ designs to date in ADR countries had to be shelved by 2007 and by 2009 no alternative designs were forthcoming.

Design Logic of ReturnHauler

Pre – ReturnHaulerTM designs had to be commended as they offered economic alternatives to standard tanker designs that ran one-way only and ran wastefully on routes where ‘return loads’ were available.

But we see pre – ReturnHauler designs had a few serious disadvantages that had to be addressed:

  • they had high decks
  • they had a high centre of gravity
  • they were expensive
  • they did comply with the new ADR regulations

ReturnHaulerTM ‘took a clean sheet’ and set out to address these four things as fully as possible.

Peter Bennetto as the ‘inventor’ and project leader in the DualHauler team with the benefit of hindsight had seen first-hand the difficulties and disadvantages of the DualHauler manufacture first-hand and then DualHauler operations in the 1990’s.

His follow up ReturnHaulerTM design became the vehicle to address the limitations of DualHauler and other similar designs.

The design logic then became :

  • get the deck down to 1 500mm (being the same as a standard flatbed)
  • achieve the resultant low centre of gravity
  • get the cost of manufacture down to the same as (or better than) a standard road tanker
  • have the tanks comply with ADR regulations

This all was possible by arranging cargo under the tanks vs. what was previously done : loading cargo on top of the tanks.

And then by constructing short (6m long), straight elliptical ADR-compliant tanks that required a minimum of welding.

And then by sourcing components from various manufacturing plants where he was going to get value for money and from component manufacturers – even if these were located on the other side of the world.