Consulting engineers firm WSP will not only use innovative technology in the upgrading of the National Route 3 (N3) project but will also aims to ensure the use of sustainable materials throughout construction.
The project forms part of the larger N3 Corridor Upgrade Programme that the South African National Roads Agency Limited (Sanral) is implementing between Pietermaritzburg and Durban, and also includes the Market road and the Epworth interchanges on the N3.
While the design phase is complete, the construction phase of this project will begin in March 2022.
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 has resulted in project delivery efficiencies that are expected to continue well into the operation and maintenance phases of the project, says WSP Africa highways, transport planning, intelligent transportation systems (ITS) and rail director Marshall Muthen.
“The digital design also allows for future technologies to be easily incorporated into the lifecycle of highway infrastructure, which includes the use of connected and autonomous vehicles, ITS for traffic and incident management, artificial intelligence and robotics in the operations and maintenance phases.”
The designs have also been developed using fully three-dimensional (3D) digital models, which, according to Muthen, allow for seamless collaboration between the various engineering and construction disciplines.
Implementing the BIM and digital design strategy, as well as the developed 3D digital models, allows for imperative information of the design development to be fully accessible during all future phases of the project. This ensures that informed decisions are made during construction and the future management of highway infrastructure, he adds.
Moreover, during the construction phase, the engineering team will update the digital models with real-time as-built information, creating what is referred to as a digital twin of the infrastructure, containing the design and construction details.
These digital technology tools include drone surveys, which will be used to capture and digitally record real-time construction activity as it progresses. After construction is complete, the digital model will be transferred to the road authority for integration into their asset management systems, says Muthen.
Further, the N3 project incorporates various innovations that reduce emissions and environmental degradation during the construction processes and the operation of the highway.
These, according to Muthen, 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, says Muthen.
He adds that porous, permeable materials and drainage systems are also being used to allow for the control and attenuation of stormwater, reducing the effect of erosion of the natural watercourses.
Muthen says the project will provide additional lanes on the N3 in each direction to improve safety and accommodate traffic growth to 2047.
“This also requires the widening of the existing N3 carriageways at approximately the same levels and grades as the existing lanes, including the widening of the existing N3 from two northbound and three southbound lanes to four northbound and five southbound lanes for each carriageway.”
Muthen further highlights that the median and existing road reserve will be used to accommodate the widening; however, additional land will be required in areas where more space is required.
All bridges crossing the N3 and existing interchanges would have to be replaced, with minor realignments to various municipal roads. This entails widening of the existing bridges, which will require the demolition and replacement of existing structures with new, wider bridges that will be set at similar elevations to existing structures, he concludes.