By tradition, middle children are said to be neglected, underestimated and misunderstood, and according to the long-established stereotype, they supposedly become withdrawn, resentful and lacking in confidence.
Comparing real life to the commercial road transport industry, the dry bulk tanker could well be one such sibling. While the all-pervading liquid tank truck is often associated with economic success, the gas-carrying relative is seen as a quite complex design, mainly due to the fact that it is built to transport dangerous and often flammable freight. Dry cargo – such as cement, grain, or raw sugar – is often seen as less ‘fancy’ in the world of road haulage. 
But, just as middle children Bill Gates, Abraham Lincoln, and even John F. Kennedy, the dry bulk – or silo – tank has proven that the stereotype does not correspond to reality. If it wasn’t for dry bulk tankers, for instance, grain would not be picked up from the farm to be processed and raw sugar would not arrive at the refinery, thus potentially ruining your morning coffee. Even the road you drive on and the house you live in have been built with the help of a modern road tanker.
Generally speaking, any cargo is considered bulk freight if it’s not packaged, but sold by weight or volume rather than in an individual unit – including sand, fly ash, sugar, flour, foodstuff, wheat, fodder, and other dry powder materials. As a result, the equipment used to transport these materials can be highly specialised, causing some transport companies to specialise in the transportation of one certain material.
The main job of a dry bulk trucking service is usually to take the bulk material from a production or storage area, such as a grain elevator, to a processing facility. Once there, the truck may then take the finished product to another distribution facility where it will eventually be sold to the end user, or it may go out via a more traditional trucking service after being packaged for retail.
In many cases, the difference between the equipment needed for bulk trucking versus regular trucking is quite significant. Most importantly, tankers handling bulk material must be completely sealed because the freight is not packaged, making bulk transportation more expensive than traditional freight haulage.
Today, such a tanker can be constructed of various materials, depending on the cargo it’s hauling and the region and climate it has to work in. Most commonly, you will find a mix of aluminium, mild steel, stainless steel and fiberglass reinforced plastic (FRP). Most often, dry bulk tankers are made out of carbon steel, sometimes with an inside lining depending on what is to be transported.
Loading a truck used for bulk material is usually done differently than with a traditional truck as well. Grain, for instance, may be loaded from the top after a truck has driven into a loading area located directly below where the grain will be dropped. For unloading, the silo truck can feature anything from a simple bottom dump mechanism to a complex rear tipping set up. Some designs are pressurised depending on the material they are intended to carry, or feature pneumatic blowers.
As opposed to the liquid-carting sibling, however, carrying multiple products at once in different compartments is an exception in the dry bulk field, but both share the same history. The first motorised oil tanker truck, for example, was developed in 1905 by a subsidiary of US company Standard Oil, known as Anglo-American. It was used in the transportation of fuel from railroad tankers to substations. Though these trucks were common in urban settings by 1910, rural areas continued using horses into the following decade.
Only when manufacturing capability and pumps improved, did industry see the true potential of transporting bulk on a large scale as opposed to many small barrels. By the end of World War I, the tanks – initially round and sometimes rectangular – were reconfigured to be cylindrical or elliptical, as US truck journalist Stan Holtzman pointed out in a 1997 retrospective.
It was this turning point that gave birth to the modern day road tanker as we know it. Today, we see tanker manufacturers taking the original simple concept of a big can on wheels and continuously refining it to be more efficient, economic and safe, as the industry is constantly evolving.
“Everything today is on a just in time basis, nobody keeps large stocks of anything anymore and that includes grain mills, and the number of rail lines and services into those sites has been reduced dramatically over the years as well,” says Australian transport veteran, Kelvin Baxter of Berrigan, New South Wales. “The result is tough market where performance has the highest priority.”
As a leading exporter of raw materials in the world, Australia can draw on a substantial amount of local manufacturers to serve the relatively small domestic haulage market. Consequently, transport businesses like Baxter’s family-run haulage firm can draw on a wealth of knowledge and expertise in the dry bulk segment, especially in regard to the use of high productivity vehicles, such as the B-double.
Regardless of the configuration, the key challenge to consider in designing a modern dry bulk tanker, according to Baxter, is the freight’s interaction with the construction material, next to payload and compliance to local road and design rules to control the minimum standard required for the safety and well being of the community. In regard to suspension systems, modern transport companies tend opt for the best compromise between weight and resilience, depending on country of operation and the load they haul.
Apart from the construction of the tank, it is the load itself that has to be considered. The type of bulk cargo being transported affects the combination’s overall weight and therefore the net amount that can be transported.
Grain, for instance, has a different density than cement. The more coarse the material, the more it will restrict the overall volume that can be transported.
For every member of the tank truck family, though, the legal framework is the same. While petrol is classified as a dangerous good, for instance, grain and sugar tanker have to comply with strict food transport regulations, which are applicable in any country around the globe.
In fact, dry bulk transport has always been somewhat of a global topic, as it is directly influenced by the international trade and finance game. A rebounding construction industry in the US, for instance, has recently fuelled the cement transport market, and with the chemicals industry recovering, more work is expected in 2013. Add the revival in China’s dry bulk trade and steady growth in India’s trade, and dry bulk demand appears set for a healthy revival in 2013.