A golden threshold at the end of the bridge, its triangulated geometry the secret twin of HOTA's Voronoi, lit by the crossings of every passerby.

The Green Bridge carries walkers and cyclists over the Nerang River from Chevron Island to HOTA, Home of the Arts, and our concept for its southern landing imagined the end of that crossing as a gateway in the fullest sense: a threshold where daily life gives way to the creative life of the Gold Coast Cultural Precinct. The journey over the water culminates in a sweep of gold around the j-curve of the landing, an embrace of arrival, opening onto an elevated outlook over Evandale Lake toward the precinct beyond.

The geometry of the concept begins with a quiet joke and ends in deep structure. ARM Architecture's precinct masterplan is built on the Voronoi, the organic cellular pattern that fills the HOTA landscape, a pattern so beloved of computational designers that the software we use carries a hidden warning against overusing it. So we moved one step sideways, to the Delaunay triangulation: the mathematical dual of the Voronoi, in which the circumcentres of the triangles are precisely the vertices of the Voronoi cells. The two patterns are the same information expressed two ways. Our triangulated passage around the southern landing therefore belongs completely to the masterplan's geometric family while looking wholly its own, a differentiated threshold between the everyday and the voronoi filled wonder of HOTA.

The city's theme for the artwork was water, after the Gold Coast motto Terra Fluminum et Oceani, land of rivers and oceans, and water is where the geometry earns its keep. Watch sunlight refracting through the moving surface of the lake and the pattern it casts is a living Voronoi: caustic lines of brightness meeting at shifting vertices. The artwork holds that observation still. A bold sweeping gestural surface, structured as a tubular aluminium frame and partially infilled with gold anodised cladding panels, takes its serpentine curves from the estuarine channels of the Gold Coast itself, winding water rendered as winding gold.

And like water, the work was designed to respond. Sensors register people crossing the bridge and moving through the landing, triggering dynamic lighting that ripples through the structure in answer, the way light answers the disturbance of a water surface. By day a golden landmark within the precinct and a beacon on the way home; by night a responsive instrument, animated by every crossing.

The concept was developed for the 2018 southern landing competition and remains unbuilt. It stands in the studio's lineage of thresholds and gateways: geometry drawn from context, form drawn from water, and an artwork completed only by the people who move through it.