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Construction of the Msikaba Bridge near Lusikisiki in South Africa's Eastern Cape province, which started in late 2019, is advancing and is expected to be completed in the last quarter of 2024.

The Msikaba Bridge, which will span the 198-metre deep Msikaba River gorge, forms part of the South African National Roads Agency Limited’s (Sanral) N2 Wild Coast project and is being constructed by the CME JV, a partnership between Concor and MECSA, both 100% black owned South African construction companies. 

The bridge’s four huge anchor blocks are at an advanced stage of construction. Over 50% of the concrete for the bridge’s two 127 metres high pylons has been poured, and the complex deck construction phase of the project is about to start.

The project is also maintaining its impeccable safety record. It recorded 3 million Lost Time Injury (LTI) Free hours on 21 October 2022, despite challenges that the construction presents, including working both at extreme heights and depths of up to 20 metres in excavations.

Concor’s project director, Laurence Savage, said Msikaba’s cable-stayed bridge is probably the most complex structure of its type ever to be built in South Africa and probably in Africa. 

“At 580 metres in length, it will be the longest cable-stayed bridge – in terms of the main span – in Africa, and it will have the second longest main span of any bridge on the continent. At 192 metres above the floor of the gorge, it will also rank as one of the highest bridges in Africa, only exceeded by the Bloukrans Bridge at 216 metres and, once it is completed, Mtentu at 223 metres,” he said.

The bridge is being built from both the north and south banks of the gorge and comprises two identical “halves”, each spanning 290 metres, which will meet mid-point over the gorge. Each half is supported by 17 pairs of cables attached to 127-metre high inverted Y-shaped concrete pylons, one on each side of the gorge. The pylons are back-stayed into the anchor blocks by 34 pairs of cables – 17 on either side of the gorge. 

With the anchor blocks approaching completion and the legs of the pylons – which make up the first 20 metres of the pylon structures – already complete, the project’s focus will be on the construction of the circular pylon spires and the composite steel and concrete bridge deck.

The spires taper from a diameter of 6 metres at the point where they start (the top of the inclined legs) to 4.5 metres at their full height. The CME JV is using a custom-designed, four-level, 15-metre high climbing formwork system to construct them. The pylons are both expected to be completed in September 2023.

Construction of the bridge deck must consider the significant wind loads with gusts up to 80 km/h that can sometimes occur at the site.

The first 24 metres of the deck on either side of the gorge is a reinforced concrete ladder deck cast into the first steel deck segment, known as deck segment zero – DS0. Because of crane access restrictions, DS0 will be slid laterally into place before reinforcement is installed and concreted. The remaining segments, DS1 through to DS17 on either side, will be installed using the free cantilevering method, with each segment installed in sequence.

A gantry will be used on either side of the gorge to place the deck segments in position. These are large 160-ton assemblies, each roughly the size of a tennis court in surface area. They will launch the deck segments – an average weight of 84 tons – out over the gorge, then rotate 90 degrees, lower, align with, and then connect them with the previous segments. Closure at the mid-point of the deck is expected to be achieved in the second quarter of 2024.

CME JV has formed close ties with local communities. “We have worked very hard – and at considerable cost – to ensure that the project has the full support of surrounding communities and that the benefits stemming from construction are localised to the greatest extent possible,” said Savage. 

The CME JV has recruited about 70% of its workforce locally and has identified and supported a host of local SMMEs, with about 40 appointed sub-contractors and suppliers. 

Top Photo: A view from the South pylon across the Msikaba Gorge to the North pylon (supplied by Concor Construction)