AECOM SA: Engineer
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N1 Freeway (Ben Schoeman Highway)
As part of the Gauteng freeway improvement project SANRAL (South African National Roads Agency SOC Ltd) commissioned AECOM SA (Pty) Ltd (then BKS (Pty) Ltd) and Mathews & Associates Architects to design the parapet cladding and lighting for the Nellmapius bridge.
The bridge had to act as a gateway to the recently completed Gauteng Freeway improvement Project. The notion of random and the art of origami were combined to reflect as a metaphor for the many facets of the province of Gauteng and the country as a whole.
Designs from other disciplines using fractal geometry were used as precedents and the design development process was hands-on, using paper models to conceptualise and generator the final design and to explore the three-dimensional sculptural qualities which the bridge had to portray.
To simplify the manufacturing process only two angles were used in the entire facade design and five panel types were designed which can be connected in various configurations to create a completely random appearance. Steel was chosen as the facade material for its sculptural and recyclable properties. The I-beam light masts create additional height and are positioned at random angles between the facade panels as a separation element. This accentuates and celebrates in an honest way, the fact that the steel panels are only parapet cladding which have been bolted onto the bridge, and that hey are not integral to the design.
The height of the panels prevent pedestrians from throwing objects onto the N1 beneath while the Origami shapes also help to deflect sound, thereby making it more pleasant for pedestrians on the bridge and a safer bridge for motorists passing below.
Lighting design played an important role as the three dimensional effect had to be retained at night. The lighting designer lit each panel from the bottom with LED cold white lights to accentuate the panels' white colour and to create a dramatic effect whereby only the bottom facets are lit. This further highlights the three dimensional random effect of the bridge panels and projects a jagged heartbeat line on the night sky.
The external face of the I-beam light masts are lit from the top, fading downwards, and on the inside there is also a light at the top of each mast shining down onto the bridge. This is not only necessary for aviation safety but also to give rhythm and light to the motorists and pedestrians using the bridge.
An additional innovative decision is that this is to be one of the first bridges in South Africa to be lit with solar energy. These panels will be housed in a sculptural structure placed on the north western embankment of the highway to best orientate the panels while also protecting them from theft.
(Mathews & Associates Architects - 2013)
All truncated references not fully cited below are those of Joanna Walker's original text and cited in full in the 'Bibliography' entry of the Lexicon.