Solution to KZN traffic challenge creates landmark

Written by Hlengiwe Ngobese

Peak hour traffic jams will be thing of the past for motorists travelling between uMhlanga and the KwaZulu-Natal north coast with the completion of one of the longest structures ever built in South Africa.

The one kilometre-long incrementally launched bridge forms part of the improvements undertaken by the South African National Roads Agency (Sanral) at the N2/M41 Mt Edgecombe Interchange, north of Durban.

The interchange was built over one of the province’s busiest intersections without the need to close any of the roads permanently, using an incremental launching technique.

Incremental launching involves casting 12 to 30 metre-long sections of the bridge superstructure on site and then pushing the completed section forward along the bridge axis.

Improving traffic flow

The project manager for Sanral’s eastern region, Corné Roux, said due to the expansion of the uMhlanga and La Lucia Ridge areas, the existing interchange had been operating at capacity, with vehicles backing up on the M41 and onto the N2 in peak hours.

“An additional 40 000 vehicles enter or leave the N2 from the M41 daily, resulting in substantial queuing of vehicles during the day. This, together with expected future expansions and the anticipated development of the Cornubia area, required the existing interchange to be upgraded in order to improve the flow to and from the N2 and M41 to the supporting road network,” he said.

“Constructing one of the longest structures ever built in South Africa over one of the busiest intersections in KwaZulu-Natal successfully, without ever closing any of the roads permanently, bears testimony to the success of the selected construction methods and materials,” he said.

Roux said the Mt Edgecombe interchange upgrade has changed the landscape forever and is sure to become a well-known landmark in years to come.

Gert van Schalkwyk, resident engineer (structures) for consulting engineers SMEC South Africa, said Bridge B0215 has a deck length of 947m, which not only makes it the longest incrementally launched bridge in the southern hemisphere, but also one of the longest structures in South Africa.

It has 23 piers, of which the highest is 26m, with typical spans of 42m. The longest span is 50.5m.

World-class engineering

What sets B0215 apart is not only its sheer size and length, but also the fact the bridge was constructed in two decks which were both incrementally launched from opposite sides.

“Given the size of the decks and the fact these decks were launched from the two opposite ends of the site, [the accuracy of the] final position is a testimony to the workmanship and world-class engineering capabilities in South Africa,” said Van Schalkwyk.