Iconic Msikaba Bridge makes STEADY PROGRESS

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

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

With the anchor blocks approaching completion and the legs of the pylons already complete the construction of the circular pylon spires and the composite steel and concrete bridge deck can proceed.

The spires taper from a diameter of 6m at the point where they start (the top of the inclined legs) to 4,5m at their full height. To construct them, the JV is utilising a custom-designed, four-level, 15m-high climbing formwork system. The pylons are both expected to be fully complete in September this year.

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

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

An interesting aspect of the project is the close ties which have been forged by the CME-JV with local communities. “We’ve 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,” says Savage.

Not only has the CME-JV recruited about 70% of its workforce locally – all of whom have received intensive on-site training – but it has identified and supported about 40 local SMMEs which have been appointed as subcontractors and suppliers.