|
Typical examples are Hoopstad and Tikwana in the Free
State. Nearest place of any size is Welkom, 60kms
distant. More than 50 000 people in the region are
already feeling the benefit.
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 township to replace existing
disintegrating roads.
In Hoopstad, the work 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, however.
“Whatever kind of road you build, there is always
going to be a rainy season, which means storm water,
and the rain had got to go somewhere,” Danie says.
“But how do you provide for this in the most
economical way?”
Using an engineering roads design software, called
Civil Designer, developed by the Cape Town firm
Knowledge Base, NEP engineers incorporated 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 naturally collects and runs down
that edge. The 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 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 and Roads design
modules were harnessed to produce the drawings,
surface modeling 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) |
