Rail transport in South Africa’s Gauteng Province entered the first-world arena in 2011 with the opening of the Gautrain Rapid Rail Link (GRRL), the first of its kind in Africa. For a multitude of commuters and travelers to OR Tambo International Airport, it is now part of everyday life, serving the province with a rapid transport service, offering a safe, efficient, and reliable service.
One of 10 spatial development initiative projects implemented by the Gauteng Department of Public Transport, Roads and Works (Gautrans), the Gautrain contributes significantly towards the economic functioning of the Gauteng area. Capable of operating at 160 km/h, the GRRL is a state-of-the-art dedicated light rail line supporting a fast transit system between three anchor stations at Johannesburg, Pretoria, and OR Tambo.
The network consists of 80 km of rail linking the three anchor stations, and includes seven other stations. Engineering, design, and advisory consultancy firm Zutari was awarded Detail Design Package 6A, which included the Centurion Station. The package also included Viaduct V5c, which was not only the single longest viaduct on the project but was also founded on extremely difficult subsoil dolomite formations in an urban environment.
“We had to overcome the significant design challenges that Viaduct V5c presented,” recalls Loest van Eeden, Zutari Transport Leader. “Innovative solutions and unique engineering design enabled us to address the interaction between the operational requirements, the structural limits, and the geological features of the site.”
Innovative solutions and unique engineering design enabled us to address the interaction between the operational requirements, the structural limits, and the geological features of the site.
While V5c is similar in appearance to other standardised viaducts in the network, some of the unique design solutions that distinguished it were:
- Subsoil conditions necessitated the design and implementation of floating foundations, as well as the installation of a continuous welded rail on top of the structure.
- This type of foundation resulted in much larger structural movements than piers founded on rock. Predicting the behaviour of the complete system was essential to the overall structural performance of the viaduct.
- Four different foundation types were used to support Viaduct V5c, mainly due to construction restraints and the complex nature of the area’s geology.
- Piers and their associated foundations had to be designed to accommodate possible sinkholes.
- The viaduct’s superstructure was constructed using the match cast segmental construction method widely used for long viaducts in other parts of the world. The Gautrain project was the first to implement this method in South Africa.
- The design had to conform to strict aesthetic and environmental parameters, as well as an African woven basket pattern for the parapets along the viaduct and tree-shaped standard concrete piers.
“Our bridge, geotechnical, and road experts created skilled engineering solutions that overcame the challenges associated with the longest viaduct on the Gautrain project. This was a significant contribution to implementing a cost-effective, efficient, and environmentally friendly transport scheme for the most densely developed area in Gauteng,” concludes van Eeden.
This was a significant contribution to implementing a cost-effective, efficient, and environmentally friendly transport scheme for the most densely developed area in Gauteng
*The Aurecon Africa business has been officially renamed Zutari as at 21 July 2020. Zutari acquired Aurecon Middle East on 20 November 2020.