* DESIGN OF
THE YEAR 2009

Henderson Waves was commissioned by the Urban Redevelopment Authority of Singapore to be constructed following an open international competition to turn the Southern Ridges into a new nine-kilometre recreational and leisure destination. The eyecatching bridge, the highest pedestrian bridge in Singapore, springs from a scenic location off Mount Faber and spans 284 metres across Henderson Road to Telok Blangah with a flowing organic form of seven “wave” spans.

Designed by RSP Architects Planners & Engineers (Pte) Ltd and IJP Corporation Ltd, UK, the bridge has been carefully integrated into the natural landscape connecting existing pathways and parks to provide natural and continuous access from both hills. The team’s design philosophy rests on a belief in “socially responsive and sustainable designs which create a positive impact on both people and the environment”. Drawing on this philosophy, the inspiration for the organic surface form of undulating crests and troughs came from the abstraction of the Southern Ridges’ natural landforms and the desire to create a destination of event spaces for spontaneous social interactivities.

The innovative design concept for the bridge is a folded three-dimensional surface-form cleverly created by a mathematical equation articulated as a continuous organic and structural form which bends, undulates and ascends in a singular movement. The structure is also functional, flowing, forming and reforming into access ramps, balustrades, benches and shelters for leisure walking and scenic viewing for the public. At night, the bridge is lit like a lantern, setting a distinctive landmark in the previously under-utilised Telok Blangah Hill Park and understated nearby neighbourhood.

To connect the two ridges of Telok Blangah and Mount Faber parks, the design process, digital and physical modellings, structural analyses and fabrication methods were integrated simultaneously from an early design stage to its final completion. The process involved studies of laser-cut models of varying scales to achieve the desired visual definition of the ribbed surface and, thereafter, continued with studies of a threedimensionally curved steel structure to be fabricated by local two-dimensional fabrication methods. This involved extensive creative interaction between the designers, engineers and fabricators to realise the project.

Liu Thai Ker of RSP Architects Planners & Engineers explains, “This project demonstrates three levels of innovation. Firstly, it was the design process of using mathematical formulas crafting the form on site to derive the final design in drawings. Secondly, the process of translation from the drawings to suit local construction practice and fabrication technology. This was carried out through discussions with contractors to formulate parts of three-dimensional elements to be re-worked in two-dimensional individual sections to the nearest three dimensional coordinates. Thirdly, special care was required in the setting out of the structural steel members in order to relate and accommodate seamlessly to the double curvature forms of the timber balustrades and back panels.”

The bridge’s underlying ecological message emerges in the naturally weathered structural concrete pylons, which were limited to minimise impact with maximum bridge intermediate spans within the tree conservation area. To reduce the ecological footprint further, as well as to provide a contextual relationship and connection to the site, indigenous Yellow Balau timber was used extensively as modular tapestry surface decks and as curved balustrades and backrests connected on the supporting steel spans and wave structures. The timber was sourced from certified sustainable timber farms in East Malaysia and fabricated with precision using the latest technology, thus reducing material wastage.

Because the surface form is a highly accurate mathematical model with accuracies up to three decimal points, the design team found it a challenge to maintain a highly precise design and fabrication process in the fabrication of the steel structures and timber deck. Any oversight in detailing or even the slightest misalignment would disrupt the continuity of the prominent three-dimensional form that was key to the project. Close coordination across disciplines was therefore paramount.

The most outstanding aspect of the bridge, in Dr Liu’s view, is that both form and structure are integrated as one. “The form is a true reflection of the structure and vice versa. Every structural centreline is a precise manifestation of the mathematical surface. In other words, the structure is not post-rationalised after the form and this ensures efficiency in the use of materials and structure.” This was achieved only because the bridge’s formula underwent numerous studies and managed to confront doubts from experts on its feasibility. From this experience, Dr Liu noted,

“One must have the boldness and perseverance to experiment and be ready to learn from failures, and one’s creativity must not be limited by precedents.”
While it was conceived as an environmentally friendly work of art, the bridge was, above all, meant for the enjoyment of the general public, including young and old, abled and disabled, singles and families, even inhabitants of the natural habitat – “no limitations”, as Dr Liu puts it. Since its opening, the bridge has successfully regenerated the surrounding areas with life and activities. The overwhelmingly positive public feedback about the bridge has proven to be the most satisfying aspect of the project for Dr Liu. “We witness people enjoying every part of the project – relaxing on the timber seats and curve backings, strolling on the deck, enjoying the bridge’s evening ambient lighting and resting at the ribbed alcoves with cast rhythmic shades, as they traverse between the two existing natural parks. Everyone seems to find their own space to conduct their activities and develop a relationship with the bridge. It has become a landmark which everyone identifies with.”

Dr Liu hopes that the project will encourage and inspire more designers to create socially responsive and responsible designs. “We hope the bridge will perform well as a social infrastructure serving the community and encourage human interactivity and, as a result, enhance meaningful value to the aesthetic and natural environment and to those living in the nearby estates.”

On being conferred the President’s Design Award, Dr Liu says, “It’s an honour for our office and the best recognition for both the consultant and the contractor teams who had worked hard.”