The Challenge

Gisborne — focus of the world's attention as the city 'first to see the light' of the new millennium — decided to embark on a significant project that reflected their new catch-phrase "First light".

This project would be gifted to the city by the Eastland Energy Community Trust with further support from the Kaiti Hill Development Trust.

Gisborne has the unique feature of three bridges on three rivers, all within a radius of 300 metres. This forms a beautiful natural central city precinct which was underdeveloped and underutilised by residents and visitors alike. At night it was particularly dark and dormant.

Our challenge was to provide an exciting and vibrant lighting vista for the bridges of this river confluence area, that would provide a dramatic impact to attract people and to entertain them. The lighting would add to an ampitheatre for outdoor concerts.

Issues and Constraints to be considered

• glare to traffic on the bridges from the new lights
• poor reflectances of the bridges
• to achieve a significant contrast to the existing street lighting
• to work harmoniously with the river-bank development project team and their separate new lighting — along the promenade and footpath of Reads Quay
• power and data reticulation around a one kilometre circuit
• vandal protection for all light fittings and electronic controls
• the client's budget was unknown at this point but they were considering other options
• energy and maintenance costs would need to be calculated and allowed for as the Gisborne City Council would be responsible for this ongoing aspect.

The concept

The concept involved:

• a stunning dynamic colour change lighting system to light the three bridges, which would enhance the world-wide marketing opportunity for Gisborne 2000 First Light
• utilising the geography of this confluence area, which offered numerous and varied viewing angles of the bridges and surrounds at night
• lighting the natural flora as the back drop in the near vicinity of the bridges to extend the 'scene' giving linkage to the southern and eastern parts of the city.

The solution

Because all three bridges were of various construction, size and shape we decided to trial the Irideon AR500s on-site mounted in cherry pickers to determine the exact beam, angles, luminaire mounting and aiming positions. This would also provide an opportunity for our clients en masse to approve the project by seeing what the result would be.

The most effective result was using two luminaires per bridge with 13° beams shining parallel along the bridge's facade either side of the river. These Irideon AR500 luminaires have an automated diffuser adjustment that gives final control setting, depending on the bridge. The AR500 is a computer-controlled 700 watt metal halide fitting that has smooth cross-fading dichroic colour change. The six AR500s to light the three bridges are linked together by a data cable and a programmable master controller. This offers the ability to have all six lights ne colour or all six lights individual colours. Each light has an address so colour change and fades can therefore be predetermined on a 365 day clock.

The mounting heights of the bridge lights, being lower than the road, the light's aiming direction and addition of glare shields provided the necessary protection so the roading engineers could approve the installation.

By water-blasting the concrete bridge facades we were able to improve the reflectances. The addition of coloured light to the bridges offered the necessary contrast from the existing sodium street lighting. The bonus effects were very beautiful reflections of the lit bridges and palms in the river.

The oversight of the installation, with regard to power and data, proved a challenge as it was a world first to have these lights so far apart from each other working off the same master controller. We shared the same trench on the Reads Quay project for our power and data cabling which saved cost, time and disruption. The master control processor is mounted in a vandal-resistant enclosure under the rotunda which means all lights can be viewed when reprogramming or downloading a new programme.

In addition to the bridges, we lit 28 selected Phoenix palm trees with inground light fittings. Each tree has a dedicated light carefully positioned to maximise the distribution pattern of the reflector. This way we achieved the stronger inner beam directed onto the pineapple-shaped crest of foliage ,while washing the trunk and outer foliage with the outer beam. We chose green as the colour of light because it is the most complamentary colour to this environment. The Phoenix palms have provided the necessary linkage and depth of field to make this project stunning.

The Irideon inground fittings had IP ratings of 65, and are made of suitable materials for longevity in these conditions. We mounted the Irideons in custom-built stainless steel vandal-resistant enclosures. The inground lights have sturdy mesh protective grills mounted over each fitting.

The energy usage and maintenance factors for this installation are relatively low due to the use of metal halide technology, and the fact that the lights are on timer controls and are not left to go all night.

The project came within the client's budget and Eastland Energy have agreed to cover costs for this installation for fiveyears.

This project has had a fantastic result, culminating in a switch-on Gisborne opening for the lights with 10,000 people on the river-banks in awe. Subsequently Gisborne is utilising this project in various ways in marketing the city to the world. Fridge magnets and post-cards have been produced of this unique lighting scene.

The Gisborne First Light project has shown a wide and varied audience what can be achieved with the creative use of light. And they love it!