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CONSTRUCTION WORLD
DECEMBER
2015
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BEST
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JECTS
National Route 7 (N7) provides the
main long distance access route to
the Northern Cape and Namibia.
As such, it forms an integral part of the
national and regional road network and
contributes to the network’s strategic role.
This project is located on National Route
7 Section 1 of the South African National
Roads Agency SOC Limited (SANRAL) road
network between Melkbos Intersection
(km 18) and Atlantis Intersection (km 25,5)
just north of Cape Town.
The tender offer by ERO Engineers for
the improvement of this section of road was
accepted by SANRAL on 3 June 2009.
The purpose of the project was to
upgrade Section 1 of the N7 to freeway
standards by increasing the existing design
speed to 120 km/h, to improve road safety
levels over the current situation and to
increase carrying capacity to the required
levels for accommodating current and future
traffic volume increases.
A high incidence of fatal accidents
occurred on this busy route with its high
traffic volumes. Heavy mist and foggy condi-
tions contribute to the dangerous condi-
tions experienced at both the original at-
grade intersections.
The upgrading of this section of the
N7 became a priority due to safety issues.
A high incidence of fatal accidents occurred
on this busy route with its high traffic
volumes at all times.
This upgrade was therefore necessary to
improve the safety levels and to increase the
capacity. The existing Melkbos intersection
comprised a T-junction at-grade intersec-
tion. ESKOM power lines and pylons to and
from Koeberg Power Station were in close
proximity on the west side with the closest
pylon located approximately 10 m from the
shoulder breakpoint.
Similar to the Melkbos intersection, the
Atlantis intersection comprised an at-grade
intersection of MR217/R304 and the N7. The
intersection also posed safety issues.
A diamond and parclo configura-
tion grade separated interchange was
constructed. The design used was similar
to Melkbos Interchange. Traffic flow projec-
tions were also the main consideration in
determining the preferred ramp configura-
tion in this case.
The Improvement of National Route 7 Section 1
between Melkbos and Atlantis Intersections
Due to the topography with a steep down
grade on the eastern side, constructing the
interchange with MR217 passing over the N7
was not practical. The resultant grades were
too steep for safe vehicle operation and also
had negative sight distance implications.
An
additional
requirement
which
formed part of the Environmental Process,
was the acquisition of a parcel of additional
land to ensure future conservation of sensi-
tive areas.
The successes of this project include the
following:
• safety improvement of the road for the
road user
• improvement of the intersections
• improvement of this section of road to a
dual carriageway with freeway standards
• improvement of the high value
endangered indigenous vegetation
environment next to the road
• the creation of job opportunities to
relative large numbers of people
• training of these workers in an effort to
provide sustainable empowerment
• the training and employment of small
emerging contractors.
Also entered Category
E
Project information
• Company entering: ERO Engineers
• Project start date: May 2012
• Project end date: January 2015
(32 months)
• Client: SANRAL
• Project team: ERO Engineers and AECOM
Joint Venture
• Main contractor: Haw & Inglis Civil
Engineering
• Consulting Engineers: ERO Engineers
and AECOM Joint Venture
• Project value: R360-million