Every day, thousands of people walk back and forth across a 50m-wide bridge that spans Johannesburg’s N1 highway and connects the Braamfontein East and West Campuses of the University of the Witwatersrand (Wits). Beneath this pedestrian deck, spread across six traffic lanes, an endless stream of vehicles rushes north and south on a relentlessly billboarded daily commute, an all too familiar visual assault on the Greater Johannesburg motorist.
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Built in 1989, what was then known as the AMIC Deck was constructed from a reinforced concrete slab cast over a profiled metal deck. The bridge is supported by steel trusses that span the bridge abutments, while the sides of the bridge are formed by large steel trusses that rise above the traversable surface of the bridge to form over-scaled balustrades. “The heavy masculine structure is an iconic presence on the highway, and it has long been heralded as a gateway into or out of Joburg,” says Craig McClenaghan, who served as project architect on the revamp project.
In preparation for the university’s upcoming centenary in 2022, a generous sponsorship by mining giant, Sibanye-Stillwater, enabled the university to appoint Kate Otten Architects (KOA) to reimagine the visual and architectural identity of the now recently renamed Wits Sibanye-Stillwater Innovation Bridge; the first phase of a longer-term initiative to reconceptualise this pedestrian connector.
“In contrast to the heaviness of the existing structure, our architectural team, in close collaboration with the client, conceptualised a light, ephemeral design for the edges of the bridge that initiates a contemporary visual dialogue between old and new,” says Otten.
Throughout the evolution of this refurbishment lighting manufacturer Regent Lighting Solutions developed a brand-new lighting element to keep up with the demands of this iconic movement. Starting with a basic, cardboard mock-up profile, fabricated to scale, experiments were conducted with various light sources to determine the output on the light post, as well as the surrounding structures.
“Reducing the bridge edges to their essential structural components, all new interventions were carefully checked against weight-bearing capacity and located inside the existing structure so as not to encroach on the road reserve and minimise complexities around safety – particularly in terms of working over a busy arterial motorway,” says Regent.
The designers from Regent, along with the structural engineer from Calibre, were heavily involved to ensure that mounting method, fixture intervals, and weight distribution of the additional 366 light elements would not compromise the structural integrity. The design is deceptively simple and attaches to the bridge structure discreetly, adds Otten.
After various developments in shape output, manufacturing methods and finishing, a single vertical element was fabricated as a prototype for final testing before large-scale production could kick off. Within five weeks, the urban light elements were fabricated, assembled and installed, repeating down the length of both edges of the bridge, forming a semi-transparent, comb-like surface. Each post is a triangular aluminium extrusion that is 4.2m in length, precisely laser cut and machined to achieve all the necessary detail, with each face being rendered in a different, carefully selected finish. Acknowledging the colour palette developed for the Wits-100 campaign, hues of blue and yellow were selected for the two outer traffic-facing faces, with the inner pedestrian-facing surface being rendered in a warm charcoal matt. “With careful placement and alignment, the triangular plan of the post enables a tight spacing between posts on the pedestrian edge that open more generously towards the vehicular side, heightening spatial depth and visual drama,” adds the lead architect.
Electrical engineering firm DELTA Built Environment Consultants, structural engineers Calibre Consulting Engineers, and lighting specialists Regent Lighting Solutions united to bring the bridge revamp to life. McClenaghan adds, “Each triangulated post houses two LED luminaires. In both instances, the luminaires are concealed in carefully – almost surgically – sculpted niches within the extruded profiles. Facing the traffic, a sharp blue light near the top of the post casts a dramatic wash down the length of the triangulated post, reflecting on the bi-coloured surfaces of its blue and yellow neighbours, illuminates the horizontal line of the existing corten truss, then finally creates a blue curtain on the road below.”
The second luminaire is concealed near the base of the post on the pedestrian side, casting a warm golden glow from inside its carved concave casement, illuminating the ground surface for safe night-time passage across the bridge. Residual hints of blue and yellow flicker as pedestrians pass by.
“Collectively, both lighting types form a series of parallel lines – one touches the highveld sky as pin-pricks of blue, and the other a knee-high trail of golden squares... and into the pragmatic function of each, a variation of unexpected moments emerge from the meeting of shadows, reflections, solid and void,” explains Otten.
The bridge itself is experienced in several contrasting ways – pedestrian & vehicular, day & night, north & south – each determined by a unique combination of characteristics such as colour, light, shadow, movement and perspective.
The design process was an intense step-by- step collaboration between the architectural firm, the client, engineers and lighting designers, says Otten. “This was to ensure the dynamic range of experiences were carefully considered and (where possible) curated through a series of intense workshops, sampling and testing, beginning with the appearance and function of form, the possibilities and feasibilities of fabrication, the realities and challenges of repetitive assembly, the relationship between natural and artificial and then finally, the atmospheric choreography of surface, colour and light, in the ever-changing Highveld sky.”
The new balustrade is and does many things – it is a safety barrier, a light installation, and a contemporary architectural gesture that hints at the celebration of the university’s history and the optimism for its future.
“Without tampering with the design clarity of the original bridge layout, it acknowledges its part in the historic narrative of the structure, without judgement,” says McClenaghan. “Its presence also celebrates the renewal of existing and new partnerships. But it is perhaps the way the design seeks to achieve these things that sets it apart from similar structures that scream for attention along our vehicular gauntlets.”
Otten adds, “The bridge design challenges the very notion of a ‘billboard’... but instead of witty slogans, seductive imagery or competitive branding, it offers a range of experiences through an unexpected sense of delight, optimism and hope, momentarily along a journey.”
RLS is honoured to collaborate with award-winning architectural practice Kate Otten Architects, representing a large number – and broad range – of architectural projects over a 35- year period, two common threads are evident in the professional ethos of all work undertaken: An uncompromising commitment to the craft of making, and a courageous commitment to societal transformation.
Enquiries: www.kateottenarchitects.com, www.regentlight.co.za
Images by: eimage/G2a1reth Gilmour
