Soft Rubber, Hard Roads

When calculating operating costs, averages are often used for budgeting, but they should always be treated with caution. In a large fleet of identical vehicles all using the same route, an average cost will generally be an accurate cost. A small fleet operating on significantly different routes, however, will require a more nuanced approach, writes JIM WARD.

Take the case of an operation running three low-tare rigid drawbar combinations in the Eastern Cape. One runs inland, while the other two vehicles deliver northbound and southbound respectively, along the coast. The inland routes are predominantly tarmac; the north and southbound routes are a mixture of highways, district roads, and minor gravel roads.

The trailers are equipped with 385/65 super singles, so reviewing the equivalent costs of other similar operations is a useful comparison, but their costs are mostly generated from high mileage, on-road operations. Finding their overall average to be about 47 cents per km (cpk), the contract manager ups his trailer tyre budget to a conservative 75 cpk.

Inexplicably, within the first few months, trailer tyres begin to cost a horrific 95 cpk, and the contract manager is torn to shreds each month-end about his high tyre costs. So, what went wrong?

This is where a thorough approach comes in: he used an entirely different operational average instead of a locally adjusted average, and never investigated the reason for his financial haemorrhage. Two of the vehicles were more or less aligned with their equivalents in other provinces, so what was driving up costs on the third combination?

With trailer design, several disparate forces must unwillingly come together, trying to reconcile different agendas to find a compromise. You may only get these market forces around the same table on one afternoon, once every few years.

The trailer designer wants low tare, high payload, high design strength, and nice aesthetics. The production manager expects fast build times and easy fabrication processes. Marketing, looking at buyers’ interests, wants low capital cost, high payloads, and a long operating life. The technical department pushes for ease of maintenance, high repairability, affordable spares, and fast delivery times.

Finally, the transport operations manager demands minimal maintenance, maximum payload, minimal downtime, and high residual values, all partnered in an unlikely marriage to low price.

In all of the above, one important person is often neglected: the client, in this instance a farmer in the Eastern Cape’s Border territory.

For many farmers, other people’s trucks and trailers fill several unique roles. The beautiful, liveried bodywork of passing trailers offers a free service, pruning low-hanging tree branches and trimming overgrown hedges. Heavy trucks act as a gang of labourers, flattening dongas, filling ravines, and straightening cattle grids. Trucks are expected to do some free grading, using their expensive underrun bumpers and front crossmembers to cut down that tough ‘middel mannetjie’ on farm tracks.

The roads inevitably degrade, however, so when trucks eventually start to get bogged down with alarming frequency, the farmer may reluctantly fill some of the worst trenches with rubble. It is then that they expect the truck and trailer to transform into the vital role of compacter and steamroller.

The farmer’s thinking goes: “It’s a heavy rig with big wheels, it will easily flatten the piles of builder’s rubble I generously tipped onto that bad bit of road (all that reinforced concrete I had lying around from when I demolished the piggery).” 

What the farmer doesn’t consider is the rebar protruding from those big chunks of concrete – just waiting to shred those soft, wide super single tyres on every trip. “That rusted old paddock gate I cut up? No problem: once those truck wheels have gone over it, it will be lekker bru – smooth as a runway!”

Sitting around the table, the trailer manufacturers are blissfully unaware of all this. The contract manager in question, if he had investigated thoroughly, would have discovered where all the tyre write-offs and the 95 cpk pain were coming from: one short stretch of rubble, concrete, and scrap that his client was expecting a combination on lightweight axles and super singles to drive over and obliterate… one neglected design requirement.