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CONSTRUCTION WORLD
JANUARY
2015
Rehabilitation measures inclu-
ded widening and resurfacing
the road, adding surfaced shoul-
ders, widening and repairing
164 drainage culverts and
reconstructing
two
existing
river bridges as well as five major culverts,
replacement of road traffic signs, new road
markings and upgrading of rest areas. Three
agricultural underpasses were also built
to enable farmers to move their livestock
across the N9 safely. The other aspect of the
design involved the new interchange at the
junction of the N1 and the N9. This included
the construction of two new bridges, various
ramps and fill embankments.
Construction
innnovation technology
The most unique feature of the project is the
staggered arrangement of the interchange.
It is staggered insofar that the connection
of the N9 to the N1 is some 950 m to the
south of the connection between the N1 and
Sluiters Street at the entrance to Colesberg.
The constraint due to the physical proximi-
ties of the nodes precluded the use of one
overpass to achieve the grade-separation
required. It would thus only be possible to
have grade separation on one of the nodes,
whilst the other remained at-grade.
In evaluating alternative configura-
tions this was a physical constraint which
required addressing; hence the final design
PROJECT PROFILE
included two overpass bridges. The south
overpass was askew to the N1 and was
115m in length, whilst the north overpass was
closer to 90 degrees to the N1 and was 85 m in
length. As a result nine ramps were required
to connect the N1 to the relevant roads.
Adding to the uniqueness of the project
were the challenges encountered during
construction. The major challenge which
presented itself at the start of construction
was the discovery that the roadbed adjacent
to the route was extremely saturated due
to exceptional rainfall during the previous
summer. As the road was to be widened on
one side along its entire length, a tremen-
dous challenge presented itself when the
saturated in-situ materials were unable to
drain due to impervious underlying layers.
A solution needed to be found and it was
agreed that the saturated in-situ material
should be removed and replaced with suit-
able rockfill material from various sources
such as widened cuttings and blasting from
borrow pits. It later transpired that the entire
N1/N9 area suffered from the same problem
and ultimately 40 000 m
3
of rockfill was
placed to enable the project to proceed. This
resulted in the programme being extended
by six months.
Corporate social
investment
Community empowerment and job crea-
tion are key features of all SANRAL projects.
The jobs created on this project varied from
month to month but almost 80% of these
jobs were allocated to local people.
About 408 employment opportunities
were created at a cost of almost R60-million
while 14 SMMEs were employed during the
construction period, with contract values
totaling to more than R62-million.
This was the first major interchange
project ever built in the Northern Cape Prov-
ince, with positive employment spin-off for
the Northern Cape economy during construc-
tion, and will also provide economic benefits
in linking the Eastern Cape economy with
the Gauteng markets.
Design
In the scoping and preliminary design stages
the entire project was subjected to a rigorous
process of compilation of alternative designs
and options. After many iterations, drawing
on the comments received during an exten-
sive public participation process, an optimal
solution to a complex set of problems was
accepted by all parties.
The project had, amongst others, the
following aim: to promote safety for both
vehicular and pedestrian traffic at two
important nodes on the N1 near Colesberg.
The first node is the intersection of the N1
(the main route connecting Cape Town with
Johannesburg via Bloemfontein) and the N9
(connecting Port Elizabeth with Johannes-
burg also via Bloemfontein).
Aerial view of N1 N9 interchange during construction.
I