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A Rotran abnormal load vehicle with truck tractors pulling and pushing a 300 ton load on a 20-axle trailer. |
While regular truck transporters face a day to day battle keeping their loads within the legal mass limits, abnormal load transporters face a different set of rules they have to comply with in order to carry plus-56 ton loads along SA's roadways, reports
Paul Collings.
Hauling a few extra tons under cover of night may help certain operators fatten their margins but when you have to move a power generator stator weighing in excess of 450 tons, there's a whole lot of preparation required involving both truck and civil engineering specialists, not to mention scores of traffic officials.
Heavy challenge
"The big challenge when transporting abnormal loads is to reach an optimum load distribution across all axles," explains Leon De Beer of Abnormal Load Transport and Technical Consultants. "This means distributing the gross mass over as few axles as possible without exceeding the 8-ton axle limit."
In order to secure the required permit to haul abnormal loads, transporters need documented proof from a transport consultant that specific loads comply with axle mass restrictions. "Generally, abnormal loads are too big to be weighed at conventional static weighbridges and special weigh scales need to be set up to check the load mass across all axles."
To ensure abnormal loads running out of Richards Bay are legally loaded, De Beer uses a portable weighbridge, the VLM (Vehicle Load Monitor) from Observer Technologies. "Generally, the loads are in excess of 120 tons and the VLM is able to weigh and record individual axles, wheels and both sides of the vehicle. It is accurate to within 2% of the legal requirement."
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The portable 'dynamic' VLM form Observer Technologies measures axle mass on an abnormal load vehicle rolling over the sensor plates at 5km/h. |
 A semi-permanent weighbridge for abnormal loads. The channel in the road allows the portable weighing system to lie flush with the surface to ensure weighing accuracy.
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Heavy arrangements
Once the weighing of the abnormal load is completed, De Beer presents the VLM printed records to the traffic departments of the provinces through which the vehicle will be driving to obtain the necessary permits and pay the fees. "It is a lengthy process," he says, "where every step of the route has to be inspected to make sure all obstacles are taken into account. Civil engineers need to check that bridges are capable of handling the abnormal load and in some cases, reinforcement of bridges is needed. Often, special detours need to be constructed and of course, traffic police escorts are essential."
When one imagines a plus-200 ton load of considerable size, like a giant petrochemical silo for example, being carried at 20 km/h from Richards Bay to Secunda on secondary routes, one can't fail to see the logistical challenges such a mission presents. "Compliance with abnormal load restrictions is crucial to ensure the safe passage of such a load. Using reliable weighing equipment that is properly calibrated is the only way to set the wheels in motion," De Beer concludes.
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Fits in your boot - Leon and Jan De Beer with the VLM, ready to hit the road to set up the system at Richards Bay. |
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