N7 upgrade project completed successfully
 | Press release: N7 upgrade project completed successfully | 29 KB | Download |
 Preview | Mynhardt Augustyn, Function Manager Construction & Pavements, SMEC Cape Town. | 3.67 MB | Download |
 Preview | The existing road was upgraded to SANRAL’s standard cross-section of 12.4 m surfaced width. | 3.32 MB | Download |
 Preview | The vertical alignment was improved with large fills using material from cuttings. | 3.25 MB | Download |
The tender for engineering services was awarded to SMEC’s Cape Town office by the South African National Roads Agency SOC Ltd (SANRAL) in 2009. This included investigations, design and construction monitoring.
Mynhardt Augustyn, Function Manager for Construction and Pavements in Cape Town, has been involved with the project since tender stage as design leader. Ivan Jacobs, Regional Manager for the Free State region, assumed the duties of contract engineer during the construction stage.
Five technical staff members from SMEC South Africa were employed on-site full time for the duration of the project, including three engineers assisting resident engineer Neels de Jager, and a senior materials technician. Fernando Pequenino, Section Manager for Geotechnics in Johannesburg, was involved during the design, attending to geotechnical matters during the construction period.
The existing road, which consisted of a surfaced width of 6.6 m with narrow gravel shoulders, was upgraded to SANRAL’s standard cross-section of 12.4 m surfaced width. Jurgen Oosthuyse, Engineer: Construction and Pavements, SMEC South Africa, says the main challenge faced by the project was that the existing roadway had considerable vertical alignment inadequacies.
“Over the full length of the road, the Olifants River runs on the eastern side of the road reserve, with valleys created by watercourses crossing the roadway at regular intervals. The existing roadway followed the contours of these rolling hills closely and reduced sight distance to the point where passing was impossible,” Oosthuyse explains.
To this extent, the standard of the vertical alignment was improved by constructing numerous large fills using material obtained from cuttings, a total of 650 000 m³ of material. Improving horizontal alignment at two major watercourse crossings required the construction of two bridges. In addition, 12 major on-site culverts, as well as several smaller culverts, were required to provide sufficient infrastructure for drainage requirements.
A hard-rock quarry was established to produce approximately 175 000m³ of crushed material for use in the pavement layers, for stone in concrete, as well as for use in stone pitching to erosion protection works.
The project provided unique challenges in meeting conflicting demands for traffic accommodation, keeping hauling distances to the minimum, and ensuring that available cut materials were put to best use as dictated by their engineering properties.
The geology consists of sandstone dipping towards the road with varying strike, mostly perpendicular to the road. The sandstone formation included interbedded clay layers, resulting in a number of slope failures in places during construction, and which were stabilised using rock bolts and mesh.
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Notes to the editor
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About SMEC South Africa
SMEC South Africa provides consultancy services for the lifecycle of a project to a broad range of sectors, which include; hydropower, transport, water, natural resources and environment, geotechnical, mining, tunnelling, urban development, renewable energy, power, government and advisory services and social infrastructure development. The SMEC Group has over 5 300 employees and an established network of over 75 offices throughout Australia, Africa, Asia, the Middle East, the Pacific, North and South America.
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