The 10.7 kilometre Toven Tunnel in Nordland, Norway, has become the world's longest lit entirely by LED lighting.
In what will widely be seen as a vote of confidence in LED technology for tunnels, the operator – the Norwegian Public Roads Administration - opted for LEDs over traditional technologies to achieve low energy and high controllability.
As the tunnel is relatively low traffic, the Admistration wanted a controllable, low-energy solution that met the relevant standards but kept energy to a minimum, especially when few cars were in the tunnel.
The project features a control system that’s unusual in tunnel installations. Presence detection and daylight sensors have been used to manage the light levels. The presence sensors automatically and instantly turn the lights on and off according to the traffic travelling through the tunnel while the daylight sensors adjust the light output according to the light outside. The installation was managed by Scanmatic, a Norwegian contractor specialising in electrical infrastructure design and construction.
The lighting has either meets or exceeds all lighting requirements in the relevant standards, with a luminance level in the inner zone of 0.7cd/m2, which exceeds the requirement of 0.5cd/m2. The efficient LED lamps typically use 21 per cent less energy compared to conventional alternatives. When combined with the intelligent lighting controls employed at Toven tunnel, this figure increases to 70 per cent to secure substantially lower energy costs.
As well as ensuring low energy consumption, the LED lamps provide a long, low maintenance lifetime. This is particularly beneficial for tunnel lighting where maintenance is often difficult and expensive. The luminaires offers a lifetime of 100,000 hours or the equivalent of 11 years – as much as 84 per cent longer than traditional luminaires. Other key priorities for the project were good uniformity, low glare and visual comfort.
Hans Øien, technical manager at Thorn Lighting, which supplied the luminaires, told Lux: ‘Toven tunnel is a new tunnel subject to a relatively low amount of traffic. This means a traditional lighting scheme would have resulted in a vast amount of wasted energy. The developer therefore wanted to employ modern LED technology to achieve optimal energy efficiency and a high standard of road safety.’
The use of LEDs in tunnels is the theme of the world’s first Road Tunnel Lighting conference, which takes place in Barcelona on 8 and 9 October 2015. Entry is free for tunnel operators and consulting engineers. See the full programme and register for a free place at www.tunnellightingconference.com.
Picture: Jan Fredrik Eliassen, Statens Vegvesen