Construction World December 2015

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

The Improvement of National Route 7 Section 1 between Melkbos and Atlantis Intersections

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.

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.

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CONSTRUCTION WORLD DECEMBER 2015