Civil Designer Showcase

When Hi-Tech Stormwater And Rural Backwater Meet

In this township of Tikwana in the Free State, dongas which they called roads and which ran like flooded rivers in the wet season, are now being turned into proper roads. It is a transformation, which sees one of the most sophisticated pieces of First World civil engineering design technology being harnessed to build roads in some of the most neglected rural areas of South Africa.

More than 50 000 people in the region are already feeling the benefit. Tikwana and neighbouring Hoopstad are typical examples of the process. Nearest place of any size is Welkom, 60kms distant.

For NEP Consulting Engineers, the challenge issued by the local Tswelopele Municipality looked simple enough: rehabilitate, upgrade and re-surface over 4kms of roads in Hoopstad itself, and build another 9kms of new roads in Tikwana to replace existing disintegrating roads.

In Hoopstad, the work has chiefly involved filling cracks, re-surfacing and slurry-sealing. In Tikwana, where the major work had to be done, new asphalt roads had to be built within the township itself.

"Some of the existing roads in Tikwana were like dongas. In the rainy weather the flood waters rush down them - they are like rivers," says Danie Kassleman of NEP.

It was not simply a matter of building roads. "Whatever kind of road you build, there is always going to be a rainy season, which means storm water, and the rain has got to go somewhere," Danie says. "But how do you provide for this in the most economical way?"

Using Knowledge Base's Civil Designer engineering software package, NEP engineers designed a storm-water channel into the actual road surface. Along one outer edge of the 5m-wide asphalt roads in Tikwana, a 1m-wide concrete strip was angled very slightly downwards so that storm water would naturally collect and cascade down that edge. The really clever bit is that traffic can still use this part of the road. Effectively, it's a 6m-wide road.
  "This represented a saving of over R1-million in the cost of the project. It meant that we were able to give the municipality a lot more road for their money," Danie says. "Equalizing cut and fill ratios is always an important costing element in road construction - in fact, in any civil engineering enterprise. The software enabled us to establish quantities very easily, and we reached a good balance of cut and fill.

"Our biggest problems were concerned with storm-water. Obviously, we couldn't fight it. So we decided to use a formula, which NEP has adopted in the past, where similar problems arose bringing the fall of storm-water to one side of the road and controlling it that way. Civil Designer was very useful in helping us to design the correct levels that would ensure that storm-water would be steered away from the immediate area to where it could do no harm or become a health hazard."

Civil Designer's inter-active Storm, Water and Roads design modules were harnessed to produce the drawings, surface modelling and final design of the roads. Danie points out, however, that NEP's "road-which-is-also-a-storm water channel" has been designed essentially for internal roads, where speeds are normally not high.

The project was funded by the Consolidated Municipal Infrastructure Programme (CMIP).


 
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