Project Description
Waterfront Auckland initially requested LDP to assess the proposed Wynyard Crossing bridge lighting design supplied by the bridge manufacturer, to check for compliance with AS/NZS 1158 Standard for a P9 design category.
Designers’s Statement
The bridge was designed in the UK and was planned as a temporary structure for pedestrian & cycling purposes. The proposed lighting design was purely functional and only included a series of standard bulkhead type luminaires, mounted on the bridge handrail supports. The lighting of the structure for decorative purposes was not included.
LDP concluded that the lighting, as proposed, did not meet the required lighting criteria and the placement of the standard bulkhead type luminaires on the handrails posed a potential safety hazard and a target for vandals.
Based on the report conclusions, Waterfront Auckland requested LDP to provide an alternative lighting design.
Concept Brief
Waterfront Auckland provided the following brief to LDP:
- To provide good quality functional lighting along the bridge footpath, complying with the requirements of AS/NZS 1158 Standards for lighting design category P9.
- To enhance the structure at night time as being an iconic element.
- To project a safe and inviting appearance, providing good visual guidance to pedestrians and cyclists.
- To integrate the lighting with the bridge structure as much as possible to provide a solution that will preserve the bridges’ visual transparency and lightness.
- Consider sustainable practices and energy efficient options in equipment selection.
LDP investigated a number of options to light the bridge. These investigations examined a variety of luminaires, lamp technologies, power supply alternatives, sustainable elements and colours of light.
This resulted in a decision to proceed with sustainable LED luminaires for the entire bridge structure due to their compact size, energy efficiency and low maintenance.
To keep the visual transparency of the bridge and for pedestrian safety reasons, our concept was for the functional lighting to be an integral part of the bridge structure rather than the previously proposed protruding attachments.
Lighting would portray the bridge as a single form whilst accentuating those parts of the bridge that move.
Limitations
- At the time of the design, the available options with LEDs were limited to a relatively small range of fittings and most with low light output designed for visual guidance purposes. This was an important limitation as the functional lighting required a higher light output to achieve the requested illuminance level.
- With the advanced state of the bridge manufacture, no penetrations, recessed lighting or electrical equipment was permitted due to time, structural and maintenance issues. Any equipment, including cable conduits, had to be surface mounted with clamps.
- As the bridge spans and the ’A’ shaped structural supports are moveable elements, the type and location of any luminaire had to avoid any issues caused during the opening and closing of the bridge.
- One of the main view shafts of the bridge has the Auckland CBD skyline in the background. The bridge lighting therefore had to be designed in such a manner that the bridge would contrast with the Auckland CBD illuminated background.
- The bridge spans a major navigation channel so it was essential that the lighting did not interfere with, or cause confusion to, vessels in terms of either glare or colours used.
Even though it is designed to be a temporary solution, the Wynyard Crossing bridge will remain on site for a period of time long enough to become part of the city landscape as a new urban icon. The new structure would form a new pedestrian route linking the Viaduct area with the attractions of the newly renovated Wynyard Quarter, and the span opening-closing activity would become a “must see” experience.
Based on this, LDP analysed the aesthetical characteristics of the bridge and its interaction with the surrounding landscape, identifying the main elements to be featured as:
- The ’A’ shaped moving supports as the most visible and iconic part of the bridge structure.
- The horizontal line of the bridge span, defined by the continuous handrail and its regular sequence of vertical supports.
- The underside of the bridges’ opening span.
The final concept included:
- Functional luminaires to be mounted on the bridge handrail supports for pedestrian safety. These would be mounted in the void space between the two vertical elements to avoid physically protruding into the footpath area. Warm white colour temperature, low glare and floor wash projection was selected to provide the required illumination of the footpath. The horizontal line of light dots created by the luminaire was also to act as a visual guidance element and accentuate the horizontal element of the bridge span.
- To contrast with the horizontal line of light dots, the two ‘A’ shaped supports are accentuated by narrow beam LED floodlights placed on the support bases, highlighting their height and linear structure. To ensure its visibility at night time a saturated blue coloured light was selected to contrast with the city illuminated background whilst also being a reference to the marine environment of the waterfront.
- To enhance the concept of the bridge “crossing” and the visual performance of the bridge opening-closing activity, the underside of the moving spans was to be illuminated with cool white LED linear luminaires running along the length of the spans. When closed, the bridge will appear as floating over the bright water but when open, the underside will reveal the lighting strips visually defining the extent of the two spans.
Solution - Functional Lighting
The search for a type of LED luminaire suitable to be fitted on the bridge handrail and capable of emitting the required lighting was unsuccessful as
they were too big for the support dimensions and/or did not provide the required light output. Considering this and the time and budget limitations, LDP developed a custom designed fitting based on an existing LED luminaire and adapted to suit.
The KKDC “MoMo” LED Strip Light was selected due to the flexibility offered by its linear body, available in a variety of lengths and with several options of colour temperature, light outputs, optics and diffused lenses.
The custom made luminaire was developed using 5 x 80mm length sections of “MoMo”, joined together by a “C” shaped metal component. This produced a 150mm high “vertical sandwich” of linear lights, fitted between the vertical handrail supports at 0.5m above the pavement surface. The light produced acts as a floor washer and orientation marker at same time, with low glare due to the frosted polycarbonate diffuser.
To accentuate the pedestrian friendly and relaxed character of the bridge footpath, Warm White 3000K colour temperature was selected and the luminaires were placed in a staggered arrangement to increase the light coverage and uniformity.
The final result was a miniaturized IP66 LED light with a total power consumption of 15W and lower maintenance requirements than any similar standard bulkhead light and an expected life of 50,000 hours. The calculations and the site measurements showed full compliance with the requested Cat. P9.
The linear surfaces of the ‘A’ shaped supports were lit with We-ef FLC Blue LED floodlights with very narrow beam, grazing the ‘A’ frame structure. As no drilling of the bridge structure was allowed the floodlights were clamped onto the supports at 2.5m height. This located the lights beyond the normal reach of pedestrians whilst achieving the required lighting effect. The lights were also fitted with anti glare guard to reduce any direct view of the illuminated surfaces.
Attention was given to the bridge underside by concealing the lights with the bridge in the closed position and achieving an evenly illuminated surface of the water below. When open the lights are fully visible with two rows of linear light on each span heading skywards, thereby accentuating the open span.
For this effect, two rows of KKDC Cold White 5500K LED linear strips with frosted polycarbonate diffusers were specified to soften the light projection and minimise glare to patrons and pedestrians and marine users. When closed, the water appears evenly lit with minimum reflected glare and, when open, the underside of the two spans reveals 2 parallel lines of light along the length of each span.
Effect
The final effect introduced a magical element into the night time landscape. The bridge can be identified from a distance due to the two strongly lit ‘A’ shaped supports, with its blue colour contrasting with the surrounding landscape.
When closer, the rhythmical arrangement of the handrail mounted lights at a human scale highlights the full extent of the footpath. Parallel to this, the blue illuminated ’A’ frame supports give the sensation of entry arches both to the city and Wynyard Quarter.
The bridge is fully visible at night time even though the structure is relatively small and transparent.
Illuminating the water below the bridge adds a contrasting soft background to the bridges’ white structure, accentuating the lightness but identifying its presence.
The movement of the bridge spans changes the effect of the bridge by virtue of the two parallel rows of white light being elevated like hands reaching up to the night sky.
