This forms part of a larger N3 Corridor Upgrade Programme that the South African National Roads Agency (SANRAL) is implementing between Pietermartizburg and Durban. WSP is responsible for the detail design and construction supervision for the upgrading of the 3 km N3 section 3 from Gladys Manzi Road to New England Road Interchange in Pietermaritzburg.
WSP has implemented a building information modelling (BIM) and digital design strategy during the design phase and will continue to do so in the construction phase. This approach has already resulted in project delivery efficiencies that are expected to continue well into the operation and maintenance phases of the project. The firm is also committed to ensuring the sustainable use of materials and natural resources throughout construction.
For the section which WSP is responsible for, the project will provide additional lanes on the N3 in each direction to improve safety and accommodate traffic growth to 2047. The median and existing road reserve will be used to accommodate the widening. However, additional land will be required in areas where further space is needed. The upgrade will also see the upgrading and, where applicable, replacement of all bridges crossing the N3 and existing interchanges with minor realignments to various municipal roads. No new access roads are required for construction access and contractors will use existing roads.
Design innovation
The digital design allows for future technologies to be easily incorporated into the lifecycle of highways infrastructure. This includes the use of connected and autonomous vehicles, Intelligent Transport Systems for traffic and incident management, and the use of artificial intelligence (AI) and robotics in the operations and maintenance phases.
The designs have been developed using fully 3D digital models, which enable seamless collaboration between the various engineering and construction disciplines.
Construction enhancements
Critically, the information forming part of the design development are now fully accessible during all future phases of the project. This will inform decisions during the construction as well as the future management of the highway infrastructure.
During the construction phase, the engineering team will update the digital models with real-time as-built information to create a digital twin of the infrastructure that contains key design and construction details. Tools such as drone surveys will be used to capture and digitally record real-time construction activity as it progresses. Following the completion of the construction phase, the digital model will be transferred to the road authority to integrate into its asset management systems.
Sustainability focus
WSP has incorporated various innovations that reduce emissions and environmental degradation during the construction processes and operation of the highway. These include the use of recycled construction materials recovered from the existing highway, such as asphalt, concrete and natural gravels; high-performance modified asphalts using polymers and recycled tyre rubber to reduce bitumen demand; and increasing the performance of the road structural layers which results in less maintenance requirements.
To ensure further sustainability, the construction specifications are taken into consideration to tightly control the riding quality of the final highway surface to reduce the fuel and operating costs of vehicles. In doing so, it creates smooth road riding quality resulting in fuel savings.
Additionally, by using porous, permeable materials and drainage systems, the control and attenuation of stormwater reduces the effect of erosion of the natural watercourses.
