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ENGINUITY
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Bosch Stemele N2 Overlay In The Eastern Cape
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Bosch Stemele Roads Division Rise To The
N10 Upgrade Challenge
Construction of high fill in Phase 2
N2 overlay under construction
Bosch Stemele, in joint venture with BCP Engineers, was
successful in a tender to SANRAL to undertake special
maintenance of a 15km section of the N2 to the west of Port
Elizabeth.
This portion of dual carriageway, from Van Stadens River Bridge
to the St Albans Interchange, had last received structural
maintenance in the mid-nineties, and the surfacing was exhibiting
severe forms of distress.
Investigations showed that with minor exceptions, the layerworks
below the surfacing were adequate for the design life traffic if they
were kept dry. This necessitated upgrades to the surface drainage
as well as subsoil drainage in both the median and outer edges of
the carriageways. As much of the surrounding terrain is very flat,
particular attention had to be paid to ensuring free flowing side
drains, resulting in the requirement for concrete lining.
This was followed by extensive repairs of the distressed roadway
surfacing by milling out the top layer of asphalt and replacing it
with new asphalt. This was restricted generally to the slow lanes.
Selected deep structural patches were also undertaken. In a
deviation from more recent practice, SANRAL requested that a
semi-gap graded asphalt be investigated for use in the overlay,
as this grade of asphalt provides better resistance to moisture
ingress amongst other beneficial properties.
A shortcoming of se