The Clifton Suspension Bridge Trust wanted to update the existing lighting of the bridge with a new solution that would display the immense achievement of the structure. Illumination has long been part of the bridge's appeal, but previously it had focused more on a lit bulb component, rather than lighting the bridge structure itself.
With the bridge a key landmark of Bristol and the surrounding region, the Trust wanted the main elements of the bridge (the deck, the chains and the towers) to be treated with concealed light sources wherever possible. In addition it was proposed to include subtle illumination to the adjacent gorge to 'connect' the bridge to its surroundings.
The Trust also required the new solution to be energy efficient and easily maintained. The length and design of the bridge meant that it was important that the new lighting system required minimal maintenance in terms of bulb replacement and control of the solution. As a result this would keep maintenance costs down, while the energy efficiency of the solution would help minimise power usage. Light pollution also had to be kept to an absolute minimum and all lighting equipment and cabling had to be as invisible as possible during the day.
To design the new lighting project the Trust appointed international architectural lighting specialist Pinniger & Partners who chose to work with fibre optic & LED lighting experts Crescent Lighting to ensure the Trust's requirements were met and due to their experience in working to tight deadlines with technically demanding requirements.
The LED system was selected for the chains from which the bridge is suspended, due to their combination of high-brightness, long life and energy efficiency. Along the length of the chains, over 3,000 white Luxeon I LEDs are arranged in groups of three, housed within custom designed luminaires. Each LED projector is focused on a small section of the chain, throwing into relief the giant nuts that connect the links together.
The LED-based luminaires appear in stainless steel with a paint finish to match that of the bridge chains. Cowls were added to the front of the luminaires to control potential glare and the LEDs are on a dimmer system so that the lighting level from them can be matched to the other lighting on the bridge.
Additional lighting elements used include linear fluorescent tubes located beneath the handrail. These fittings not only direct glare-free illumination towards the pedestrian zones and illuminate the walkway for pedestrians, but also provide gentle definition of the roadway below, and emphasise the delicate design of the iron lattice running the length of the bridge.
Within the arches of the two 26m high towers at each end of the bridge, additional uplighting is delivered via surface mounted projectors. The existing lanterns were relamped with 35W CDM lamps to ensure colour consistency, and linear fluorescent fittings were positioned out of site in the upper machine rooms to provide high-level definition to the Towers. In addition, a series of ground recessed adjustable uplights are located to provide gentle texturing of the flank walls of the towers.
Compact, surface mounted projectors, fitted with custom designed baffles concealed beneath each end of the Bridge deck, gently downlight the abutments. When viewed from the north or south, the Bridge no longer appears to 'float' above the Avon Gorge but can be seen to be connected to the structures that support it.
(Jim Evans)
