Name of the Project
N2 Wild Coast Toll Road (N2WCTR) megabridge projects.

Location
The bridges will be built over the Msikaba and Mtentu river gorges, both near Lusikisiki, in South Africa’s Eastern Cape province.

The Msikaba bridge is located on the N2, which connects the Western Cape, Eastern Cape, KwaZulu-Natal and Mpumalanga provinces, and traverses the cities and major towns of Cape Town, George, Gqeberha (formerly Port Elizabeth), East London, Mthatha, Durban and Ermelo. This includes a new greenfield section of 112 km between Port St Johns and Port Edward, including the two megabridges and several additional major river interchange bridges.

Only the new greenfield section of the project will be tolled. None of the sections between East London and Mthatha or between Mthatha and Ndwalane, near Port St Johns, will be tolled. The public participation process for the tolling of the greenfield section of the road is yet to start.

Project Owner/s
South African National Roads Agency Limited (Sanral).

Project Description
The Msikaba and Mtentu bridges form part of the N2WCTR project.

The 580-m-long Msikaba bridge will be the longest main span bridge in Africa – constructed using the cable-stayed method – and the second-longest main bridge span in Africa after the Maputo-Catembe suspension bridge, in Mozambique. With a deck height of 194 m above the river valley, Msikaba will become the third-highest bridge in Africa and the 133rd-highest in the world. The Msikaba bridge cable-stay design will ensure that the construction of the bridge will have no direct impact on the pristine gorge environment almost 200 m below, which is one of the environmental requirements in building the bridge.

The 1.13-km-long Mtentu bridge, which includes a 260-m-long main span, will be one of the longest main-span-balanced cantilever bridges in the world. Only ten prestressed concrete girder bridges worldwide have a main span of 260 m or longer. Reaching heights of more than 220 m above the river valley, it will displace the Bloukrans bridge, in the Western Cape, as the highest bridge in Africa and the southern hemisphere. The 141-m-tall Pier No 9 (equivalent to a 40-storey building in height) will also be the tallest bridge pier in Africa and the southern hemisphere.

Being one of the longest main-span-balanced cantilever bridges and one of the highest bridges in the world makes the construction of the Mtentu bridge a technically highly challenging project. The remote location and local social dynamics add to this complexity.

Potential Job Creation
So far, the Msikaba project has created work for 137 unskilled local labourers and 372 jobs for skilled persons, of whom 190 are locals.

Capital Expenditure
The Msikaba bridge project will cost an estimated R1.65-billion and the Mtentu bridge project R3.5-billion.

Planned Start/End Date
The N2WCTR project started construction in 2011. However, the major greenfield portion of the route between Port St Johns and Port Edward started construction only in 2016.

Construction of the Msikaba bridge is expected to be completed at the end of 2024.

Provided that there are no significant delays on the Mtentu bridge project, the construction period is estimated to be 49 months, including a four-month mobilisation period.

Latest Developments
Construction of the Msikaba cable-stayed bridge should be complete in the last quarter of 2024. 

Work on the project, which forms part of the N2 Wild Coast Toll Road roll-out, started in earnest in 2019.

The bridge is being built by the Concor Mota-Engil (CME) joint venture (JV), a partnership between Concor and MECSA, both 100% black-owned Grade 9CE South African construction companies. 

The bridge’s four huge anchor blocks are at an advanced stage of construction, with more than 50% of the concrete for the two 127-m-high pylons poured, and the complex deck construction phase of the project to start soon.

The bridge is being built from the north and south banks of the gorge and comprises two identical halves, each spanning 290 m. The halves will meet midpoint over the gorge.

Each half is supported by 17 pairs of cables attached to 127-m-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 comprise the first 20 m of the pylon structures – already complete, the focus of the project going forward is on the construction of the circular pylon spires and the composite steel and concrete bridge deck.

The spires taper from a diameter of 6 m at the point where they start (the top of the inclined legs) to 4.5 m at their full height. 

To build them, the JV is using a custom-designed, four-level, 15-m-high climbing formwork system. 

The pylons are both expected to be fully complete in September.

Construction of the bridge deck has to consider the significant winds that can sometimes occur at the site, gusting up to 80 km/h.

The first 24 m of the deck on either side of the gorge is a reinforced concrete ladder deck that is cast into the first steel deck segment, known as deck segment zero, or DS0. 

Owing to crane access restrictions, DS0 will be slid laterally into place before reinforcement is installed and concreted. 

The remaining segments, DS1 to 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 t assemblies, each about the size of a tennis court in surface area. 

They will launch the deck segments – which have an average weight of 84 t – out over the gorge and then rotate them 90 °, after which they will be lowered and aligned, then connected to the previous segments. 

Closure at the midpoint of the deck is expected to be achieved in the second quarter of next year.

The CME JV has recruited about 70% of its workforce locally, but it has also identified and supported a host of local small businesses, about 40 in total, which have been appointed as subcontractors and suppliers

Key Contracts, Suppliers and Consultants
Concor Mota-Engil, a joint venture between Concor Construction and MECSA Construction (Msikaba bridge contract); HVA Joint Venture (Msikaba and Mtentu bridge consultants comprising CH2M and SMEC); V3 Consulting Engineers (lead consultant – Ndwalane to Ntafufu and Kulumbe to Mtamvuna river); ERO Engineers (lead consultant – Ntafufu to Bambisana turn-off); Naidu Consulting (lead consultant – Bambisana turn-off to Lingeni); Aurecon Rohm consortium (lead consultants – Lingeni to Msikaba); Knight Piesold (lead consultant – Msikaba to Mtentu); and KBK Engineers (lead consultant – Mtentu to Kulumbe).

Contact Details for Project Information
Sanral project manager Craig McLachlan, tel +27 41398 3200 or email MclachlanC@nra.co.za.