We have all heard the cliche “a stitch in time”, but for construction workers of the Mt Edgecombe interchange “steel rod sutures” joined the overhead last Friday since the project began two-and-a-half years ago.
While motorists went about their way negotiating the labyrinth of deviations below the multidirectional bridges being constructed, history was unfolding more than 20 metres above when the longest incrementally launched bridge in South Africa neared completion. The north and south decks of the one-kilometre ramp of the Mt Edgecombe Interchange were finally joined.
The bridge forms part of the improvements being undertaken by the South African National Roads Agency SOC Limited (SANRAL) at the N2/M41 Mt Edgecombe Interchange north of Durban, connecting Phoenix and uMhlanga with Durban and the North Coast of KwaZulu-Natal.
The joining involves casting twelve 30m long sections of the bridge superstructure in a stationary formwork behind an abutment and pushing a completed section forward along the bridge axis. The sections are cast contiguously and then stressed together.
What sets B0215 apart in South Africa is not only its sheer size and length, but also the fact the bridge is constructed in two decks which are both incrementally launched from opposite sides with the intention to meet in the centre.
Both decks were successfully launched into their final position and completed in July last year. The decks were launched to within five metres from each other: the last five metres of deck was cast insitu and is referred to as the “stitch” which neatly and monolithically joins the decks together.
Like the final piece of a giant puzzle, it was the stitch that was placed in position on Friday, 4 August.