The 69-year-old Breede River Bridge, one of the longest river bridges in South Africa, was widened in 2017 as part of a larger contract for the rehabilitation of Main Road 298 (MR298) through Rawsonville, between Worcester and Wyzersdrift. The Western Cape Department of Transport and Public Works (DTPW) appointed Zutari for the project management, design of the bridge structure, and the procurement and construction supervision of the project.
Limited funds reduced the proposed widening from 11.4 m to 8.6 m across the bridge. The solution to these constraints was to widen the bridge on both sides using precast beams supported on cantilevering, which were formed by cast-in-situ reinforced concrete (RC) corbels attached to the existing piers and externally stressed together using high-yield steel tie bars.
As environmental approval for work in the river would have delayed implementation, the Zutari project team designed an innovative solution that could be constructed without any work in the water, which also reduced the risks associated with flooding. To further limit the environmental impact, ingenious hanging, moving gantries were used to complete construction work from on top of the existing deck.
Carrying out the project on a bridge of this age required solutions for numerous other technical and construction challenges such as:
- Maintaining traffic flows during construction
- Maintaining flows through a sewer and a water main attached to the bridge
- Maintaining and relocating optic fibre telecommunication lines over the bridge
- Dealing with inconsistencies in the dimensions of the old bridge
- Developing repair solutions for parts of the existing structure, including jacking up one of the decks to install bearings
Extensive bridge repair work was also successfully completed, including pier protection collars, partial reconstruction of abutments, large spall repairs, and the jacking of the north abutment to install new bearing pads.
The cooperation between the main contractors and sub-contractors, as well as the working relationship that developed between the contractor’s personnel and the supervising staff, was exemplary
“The widened and rehabilitated bridge project was completed in November 2017 to high standards and to the client’s requirements. We had provided an aesthetically pleasing and safer crossing for both vehicles and pedestrians over the Breede River. The cooperation between the main contractors and sub-contractors, as well as the working relationship that developed between the contractor’s personnel and the supervising staff, was exemplary,” says Hennie Niehaus, Zutari Technical Director.
Particular consideration was given to the social implications of the project and the company continually engaged with the affected communities to jointly explore ways of mitigating the impact of the construction works.
“The upgrading of the 525 m-long Breede River Bridge is considered an example of outstanding civil engineering design and construction, which, despite environmental, traffic and construction constraints, was completed on time and within budget,” concludes Niehaus.
*The Aurecon Africa business has been officially renamed Zutari as at 21 July 2020. Zutari acquired Aurecon Middle East on 20 November 2020.