N3 revamped with new tech 

The second section of the N3 from Dardanelles to Lynnfield Park has suffered from years of traffic congestion. To address this issue, GIBB – one of South Africa’s leading multi-disciplinary engineering consulting companies – was appointed by the South African Roads Agency (SANRAL) to assist with the design and construction of four bridge widenings, a new ramp bridge, and v-drains.

GIBB employed a host of new technologies and innovations to complete the N3 project, including a specialist traffic modelling software called Aimsun, new LED lighting for street lights, and stronger and heavier road pavement material.

“The construction industry is notoriously slow regarding the implementation of new technologies, since the commercial risks related to the use of untested technologies are simply too high. For this reason, the tendency has always been to revert back to the tried and tested methods and materials,” says Innocent Magwa, GIBB’s bridge design engineer.

“Where possible, technological advancements have been embraced and implemented. Sufficient trials were conducted to motivate the use of alternatives,” he adds.

The construction part of the project, which started in January 2021, is set to be completed by its deadline of May 2025, although it has not been without its challenges. Magwa points out that accommodating traffic on the busy road, the supply of materials from the SANRAL quarry, land acquisition, and issues around groundwater have all been difficulties the team has had to deal with.

“In addition, during the design stage, most of the existing structures did not have as-built drawings. We had to employ other means like conducting structural surveys and 3D scanning of the structure to establish the sizes, spans of the existing structures, and the amount of reinforcement on the existing structures,” Magwa emphasises.

“This information helps us establish the capacity of the existing structures and also to determine if any strengthening is required with the increased loads on the existing structure.”

During the construction phase, Magwa says that the local and regional communities would experience positive and negative effects as a result of the construction process. On a positive note, there may be temporary job creation for semi-skilled and unskilled workers. However, the local communities might experience poorer access and travelling conditions during construction. “With mitigation, the negative economic and socio-economic impacts of the project during construction are expected to be low,” he adds.

Magwa is proud of his involvement in the project and its progress to date. “I especially enjoyed the design aspect of the project, as dealing with existing bridge widenings is quite complex and requires a lot of attention to detail,” he says. “After being involved in the design part, I am currently involved in the implementation stage and the inspection of the reinforcement on the bridge sites.”