Overloaders are to blame for
deterioration, writes Alan Peat
IT'S EASIER to blame overloading for the deterioration of our roads, rather than the poor construction in the first place.
That's long been a loud cry in the road transport industry - many of whose members feel that SA roads are not built to a sufficient strength level to cope with the loads they can be expected to face.
The argument has just been resurrected by Kevin Gesseau of Ikamiji Freight - who was disturbed to have read in an article in another publication that SA roads are thin skinned in global terms.
It said that, when a new road is built here, there is only 5-10 centimetres of bitumen put down, he told FTW. In Europe it's 20-cm, and in the US 30-cm.
Is this true? - FTW asked Bob Kingdom, executive director of the SA Roads Federation (SARF).
The answer is an unqualified yes, he said.
But the reason for the disparities in bitumen thickness is explained by a number of factors, Kingdom added.
When you look at a road in France or the UK, for example, you should focus on two things, he said. The axle number allowed for is much higher than here. Also, you must take the comparative weather patterns into account.
French roads, the way Kingdom sees them, are armour-plated compared to SA - with the asphalt up to 150-mm thick.
But that's a road with a design life of 40 years, he said. In SA, a 25-year lifespan would be considered more than wise because we're a developing country - and demand could grow more than can be accurately expected.
But SA road construction is up with the best in the world, according to Kingdom.
And they are certainly not built without taking the expected load into account, he added.
When you design a road, Kingdom said, you build to an international standard sufficient to meet the traffic flow you have counted down the route.
And the resulting strength index is calculated from a pretty complex formula - taking into account all sorts of ifs-and-buts of traffic flow and the loads expected to be exerted. It's a meticulous examination of all the factors, Kingdom told FTW.
But any argument that overloading doesn't cause a lot of damage, he added, is absolutely ridiculous.
Piet Myburgh, chairman of the SA Bitumen and Tar Association, agrees.
Pavement structures in SA are designed to cope adequately with a legally loaded truck, he told FTW.
The SA design codes are geared to legal loads, he said. But any overloading will have an exponential effect on the pavement.
Overloading is blind. It wrecks everything.
It's not the initial strength of SA roads that are at fault, Myburgh added.
It's how you manage the growth of distress that determines how long a road will last, he said.
But SA roads - while exemplary when first built - are not being looked after as they should.
By the admission of the Minister of Transport, said Myburgh, only 60% of what's necessary to keep damage at bay is available in road funds.
We're not spending enough. Everybody admits that.
And Myburgh sees a good roads infrastructure in SA as being crucial to its economic development.
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