Logistics solution provider Reinhardt Transport Group COO Graham Gaskell believes that, given South Africa’s limited rail network to transport coal, road transport becomes the only available alternative.

He says road transport offers advantages, such as the flexibility to change routes if needed, as opposed to fixed rail infra- structure. Further, road haulage requires rela- tively low capital costs and will result in increased competition between suppliers, as opposed to the more captive nature of rail supply.

However, the disadvantages of using roads include its labour-intensive nature, owing to poor road conditions, resulting in increased maintenance and operating costs. “This is the result of neglected road maintenance, underfunding and gross overloading of trucks, owing to a lack of standards and monitoring by the relevant authorities,” says Gaskell, speaking at the recent Coaltrans Conference, held in Sandton.

He states the most significant disadvantage of road haulage is the increased number of operators and the increased risk to public safety. However, Gaskell avers that, by using performance-based standards- (PBS-) compliant vehicles, the disadvantages of road haulage can be counteracted.

PBS is designed to improve payloads, subject to predefined performance criteria that allow vehicles to operate beyond what is permissible within the current legislation.

This approach allows more flexibility for vehicle designers to use innovative solutions and the latest available tech- nology to meet the required performance standards, with improved safety outcomes and more effective use of the road infrastructure. The PBS approach also reduces the wear to road infrastructure, compared with conventional trucks.

Scientific and technology research, development and implementation orga- nisation the Council for Scientific and Industrial Research undertook a PBS research programme last year.

The report states that a need was identified to design, manufacture and operate a number of PBS demonstration projects in South Africa to gain practical expe- rience in the PBS approach for heavy vehicles and to quantify and evaluate the potential safety and productivity bene- fits of this approach for road freight transport.

Two PBS demonstration projects, commissioned by paper and packaging group Mondi and paper producer Sappi, have been implemented in the forestry industry. The vehicle performance standards that have been used to design the two PBS demonstration vehicles include high- and low-speed directional and non- directional manoeuvres, such as startability, gradeability, acceleration capability, frontal swing, tail swing, slow-speed swept-path – which is the extent to which the truck breaches its lane when manoeuvring – tracking ability on a straight path, static rollover threshold, rearward amplification, yaw damping and high-speed transient off-tracking.

The Sappi PBS-compliant vehicle has an overall length of 27 m and a maximum combination mass of 67 500 kg. The Mondi PBS-compliant vehicle has an overall length of 24 m and a maximum combination mass of 64 100 kg. These PBS-compliant vehicles compare favourably with the baseline (legal) vehicle of similar configuration, which has a maximum overall length of 22 m and maximum combination mass of 56 000 kg.

As part of the PBS project, a mecha- nistic-empirical pavement analysis methodology was used to assess the road wear characteristics of the two PBS-compliant demonstration vehicles. It has been shown that these PBS-compliant vehicles are more road friendly than the typical baseline vehicles.

Using this assessment methodology, other vehicle and tyre modifications that result in more road-friendly vehicles without affecting the productivity of the vehicles can be implemented.

Gaskell says that the PBS-compliant vehicles are between 3% and 5% less destructive on road infrastructure, owing to the increased length of the PBS vehicle, which allows the even distribution of the payload and results in improved balance of the truck.

In the timber industry, it was shown that PBS-compliant vehicles increased the average payload from 31 t to 48 t. This decreased average transport costs by about 25%.

The capital cost of a PBS-compliant vehicle is about 31% higher than existing vehicle configurations; however, when applying the principle over larger volumes, the overall capital cost decreased, as fewer vehicles are required owing to the increased payloads.

Operating and maintenance costs are also reduced, owing to lower fuel con- sumption and fewer vehicles being on the road. “The most significant advantage of using PBS-compliant vehicles is that they are allowed to operate under concessions on public roads,” says Gaskell.

Further, he explains that the potential impact of using PBS-compliant vehicles in the coal industry in South Africa is sig- nificant. In 2010, 50-million tons of coal was transported by road in South Africa, assuming a 200 km average lead distance, with an average current payload of 34 t and terminal times of four hours for loading and offloading.

Having established a fleet that can travel laden at about 45 km/h and about 55 km/h unladen, the current fleet required would be 5 200 vehicles, burning 500-million litres of fuel to move 50-million tons of coal.

By using PBS-compliant vehicles, the average payload is 48 t, which would only require 3 200 vehicles, burning 320-million litres of fuel to move 50-million tons of coal. “This is 2 000 fewer trucks, resulting in decreased congestion and pollution, and potentially fewer accidents,” Gaskell explains.
All the axle and axle unit loads of the PBS-compliant vehicles meet the requirements of the South African National Road Traffic Act, no 93 of 1996.

Legislation on vehicle loading focuses on the maximum permissible vehicle combination masses per axle and axle unit loadings and the ‘bridge formula’, which sets a maximum weight that any set of axles on a vehicle may carry. Gaskell believes that this formula is outdated.

“In countries, such as Sweden, Australia, New Zealand and, recently, South Africa, mechanisms have been designed in line with the thinking that legislation should not dictate what the vehicle looks like, but rather guide how it should perform,” Gaskell concludes.

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