By Emma Day, Executive Associate at JG Afrika
Entrusted with the Pavement Management System for Bakwena Platinum Corridor Concessionaire, JG Afrika is helping to maintain the N1/N4 Toll Road to the high-quality standards specified in the concession contract.
As part of this responsibility, JG Afrika and principal contractor, G4 Civils, are rehabilitating a 20km section of the slow lane of the N4 between Kameeldrift Interchange and Ga-Rankuwa Interchange.
JG Afrika commenced with the engineering design in 2020 and is now overseeing the construction works which commenced in late in 2021 with the project mobilisation period.
G4 Civils started with the construction work on the project in January 2022 and is expected to complete the work scope in August 2023. Having already completed about 60% of the scope of works, G4 has already made steady progress on this contract.
The scope of work entails milling the existing surfacing, base, subbase, and a portion of the selected layer. The base and surfacing layers are milled to a depth of 205mm and width of 3,7m and stockpiled for reuse. The subbase and a portion of the selected layer are milled to a depth of 510mm and width of 3,7m and sent to a separate stockpile. Roller compactors then compact the remaining selected layer achieving the required density in five passes. Hereafter, the milled surfacing, and base, as well as 100mm new G5 material and cement is placed and stabilised to form a new 300mm, 3,7m wide C3 selected layer. A 150mm bench is then formed on either side of the new base. After this, a new 150mm, 4m wide G1 base consisting of commercially sourced material is placed and a 150mm bench formed on either side for the new surfacing. The 60mm 4,3m-wide continuously graded asphalt surfacing consists of AE-2 binder and rolled-inchips is then placed.
Day says that the project has not been without its share of challenges. “The construction works are being undertaken along an extremely busy section of the N4. To mitigate the impact of the construction work on the flow of traffic, rehabilitation, which is being undertaken in sections, needs to be planned very carefully. Unexpected ground conditions, such as areas with underground water, have also been a challenge,” she says. To ensure that the project met Bakwena’s goals to incorporate local targeted enterprises and local labour into the project, a public liaison committee (PLC) was set up during the mobilisation period of the project. Through a tender process coordinated by the contractor, the PLC tenders were put out for various packages to local targeted enterprises. A community liaison officer was appointed to receive CVs of local labour and assist with the appointment thereof.
Day attributes much of the success of the project thus far to excellent dynamics between the engineering and contracting teams. This is in addition to the proactive and hands-on approach that has been adopted by the client, represented by Danie Verwey, Chief Technical Officer; Danie Botha, Project Manager; and Joe Reyneke, Client Representative.
