Three of Glasgow’s bridges over the Clyde, the George V, the Glasgow and the Victoria, have been dramatically and beautifully floodlit using a new light source – high-intensity light-emitting diodes (LED’s).
This is believed to be the first time LED’s have been used as the predominant light source on a bridge anywhere in the world.
Each of the three bridges is around 120m long, and the broad brief to the designer was to light the bridges’ external and under-arch surfaces, whilst taking into account the cost of installation and ongoing maintenance cost. The work was funded by the Development and Regeneration Services of Glasgow City Council and to be designed to comply with Glasgow’s City of Light strategy.
With the brief in mind, the lighting design section of Glasgow’s land services conducted trials with conventional light sources such as linear fluorescent, high-pressure sodium and self-coloured metal halide before selecting Philips LEDline utilising high power LEDs as the most appropriate luminaire/light source to fulfil the brief. The LEDline was able to create intense show-stopping effects, with all the advantages of extra long life, cool running and simple maintenance.
In a design that recreates the colours of Scotland’s St. Andrew’s Cross, the bridge balustrades are lit by Philips 58W linear cool white LEDline floodlights, chosen for the clean line and low profile. Philips blue LEDline emitting at 470nm lights the under arch surfaces with a smooth continuous wash of colour. The piers are highlighted with 150W metal halide floodlights. The scheme was installed by Lightways (Contractors) Ltd. on a contract won under tender.
From all viewing positions the night-time effect is dramatic. There is a strong clarity of colour, continuity and emphasis of the bridge structure. The relationship of the blue underside arches with the white balustrades complements the bridge, and the even continuous effect resulting from the linear floodlight creates a beautiful reflection from the water below.
John Fagg, Glasgow City’s designer responsible for the scheme, says: ‘The excellence and strength of the colour far exceeds our original aspirations. It provides a bold and positive statement linking the two sides of the City. It also provides a constant visual moving effect with the changing heights, waves and tidal flows of the river.
Our challenge was not only to produce a beautiful scheme, but also to provide a low cost maintenance installation. The application of LED’s for floodlighting three major road bridges should do the job. The luminaries should last for 20 years, burning for 2,500 hours a year, so effectively this is a fit-and-forget installation.’
LEDLines – floodlights of the future?
Glasgow’s bridges are lit by easily-installed Philips LEDLine 1.2m linear floodlights, each containing 4 modules of twelve high-brightness Luxeon Star 1W LEDs. The LEDs used are Luxeon LEDs by LumiLeds, a company that is a joint venture between Agilent Technologies and Philips Lighting. Luxeon LEDs are a considerable technological advance on the tiny red, green and yellow LED’s used for signalling purposes on today’s electrical equipment.
Like all LED’s, LumiLeds Luxeon LEDs produce a specific wavelength of light at the junction of a solid-state diode ‘poisoned’ with materials chosen according to the colour of light required. Consequently, they are entirely solid-state, with no filaments, glass envelopes or vacuum tubes to break or go wrong, and therefore have life expectancies usually equalling or exceeding that of the equipment in which they are installed.
Unlike ordinary LED’s, LumiLeds Luxeon LEDs contain heat sinks to increase power handling capability and therefore light output. Because the light-emitting area of an LED is small (typically 1 sq.mm), precise optical control is possible. Whilst lens systems can be designed as part of the LED module to focus the light, in the case of the Philips LEDline floodlights, Philips have created an optical system built around the LED. The LEDline features a unique optical collimator (lens), designed to efficiently capture the light emitted by the Luxeon LED and focus it into an intensive tight 2 x 3° beam. Spacing and light distribution are designed so that the floodlight appears to project a continuous linear sheet of light. The result is a beam that, in this case, has the power to wash concave curved surfaces up to 20m. This enables the LEDline to create a blanket lighting effect on the under arches of the bridge, grazing the surface to reveal the form and texture in a way that would be impossible to achieve with any other luminaire/light source combination currently available.