To ensure safety on stretches of open road involves visibility over relatively large distances, generally 30 metres or more, to account for the high traffic speeds that may be present. To achieve this at below optimal lighting levels for our eye requires a different approach to lighting which is to light the road surface, making objects appear in silhouette against the bright surface. However where speeds can be expected to be lower and objects closer, such as in conflict areas or tunnels, this no longer works as the road surface may be visually below the object outline preventing it appearing as a silhouette, and therefore the objects themselves need to be lit as opposed to the road surface. These changing requirements are reflected in the design criteria, luminance for traffic routes and illuminance for conflict areas and tunnels.

 

In Europe lighting requirements for roads are given in the document EN 13201 Road Lighting. This document is in multiple parts and describes how to decide the relevant road class and then the lighting requirements that this class requires. Lighting requirements for tunnel lighting are given in document CR 14380 Lighting Applications – Tunnel Lighting. However this document is a report not a standard and should be used in conjunction with local practice.

 

Best practice
The luminaires should be appropriate for the local climactic conditions. For open areas the fitting should ideally be shaped and mounted to minimise windage, which is the effect of wind producing a stress on the luminaire and all mounting equipment. All brackets, columns, etc. should be rated to withstand the maximum windage that will be encountered. In enclosed spaces such as tunnels the luminaire should be capable of withstanding mechanical shock caused by possibly near-continuous vibration as well as the poor air-quality which may contain corrosive pollutants.

Positioning of luminaires should provide maximum guidance as to the geometry of the road, giving a coherent visual story to a road user. It should be ensured that some light spills behind the edges of the road to allow visibility of objects off the carriageway that may pose a hazard, however this should be controlled to prevent excessive obtrusive light.

For tunnels the lighting should provide a smooth transition between the entrance, tunnel interior and exit zones allow the eye to adjust to the different ambient light levels. All tunnel surfaces should be lit to ensure a comfortable and safe passage through the space.

For both roads and tunnels care should be taken to prevent distracting flicker caused by bright sources of light travelling in a periodic way through the field of view (the car windscreen). This can give a similar effect to a stationary light dimming and increasing in response to the electrical supply.

The use of photocell switching to react to levels of daylight or timed on/off can ensure the correct light at the required time. Dimming of lighting at hours of low usage, such as the use of bi-power dimming which reduces the lighting during the early hours of the day, can significantly reduce energy usage. In addition a more advanced lighting control system can allow the lighting levels to be set to the requirements of a situation, such as raising the lighting levels at the scene of an accident or traffic congestion whilst allowing central monitoring of lighting to ensure peak light management with optimal maintenance.

High efficiency control gear that minimise electrical losses, especially for higher power lamps, help increase energy efficiency, whilst the use of a high quality optic to control the light helps reduce waste light that falls outside the target area.

 

Visit www.novelenergylighting.com today to explore our Megaman LED retrofit solutions, or call: 0208-540-8287, email: sales@novelenergylighting.com

 

– Isaro

– Isaro LED

– GTLED

Now, those old fluorescent and high-pressure sodium lamps have been replaced by over 600 linear LED luminaires, arranged in unbroken lines. It looks way better, and the lights should last about 10 times as long as the old ones – 20 years instead of two.

The new lights, supplied by Philips, will also use significantly less energy.

To help drivers adjust their vision when entering and leaving the 284-metre tunnel, the lights near the ends are brighter than the ones in the middle, providing 156 cd/m² of light near the exits and >2.0 cd/m² (dimming to >1.5 cd/m² at night) in the middle. They are also dimmed as the day progresses, to match the level of natural light or streetlighting outside the tunnel.

With a projected life of 20 years, the energy savings and reduced maintenance costs are expected to generate around £850,000 ($1.3 million) of savings.

The work was done by engineering services firm SPIE for Amey, the principal contractor for the Highways Agency. Paul Diamond, tunnel manager for Amey, said that since the installation of the new LED lighting, ‘I have reduced my overall maintenance costs, saved a substantial amount of money in energy costs, reduced the carbon footprint and reduced the risks for the operatives.’

The new system complies with the updated standard BS 5489:2 2008 and is designed to provide better uniformity and colour rendering than the old scheme. Because the lights are in an unbroken linear arrangement, any failures (which are unlikely in any case because of the long life of LED lights) would have little effect on the overall scheme. A point-source installation, on the other hand, can easily fall below minimum lighting levels if just one or two lamps fail.

And because the new system uses LEDs, the lights can also be instantly turned back on after a power failure (unlike high-pressure sodium which needed time to cool down first), are fully dimmable, and work well in low temperatures.

The result of the upgrade project is that the annual energy consumption of the tunnel lighting has been reduced from 660 MWh to 154 MWh, a saving on energy costs of nearly £64,000 ($100,000). The tunnel will also save around £28,000 ($44,000) on maintenance, so the total annual savings will be around £92,000 ($144,000). The predicted savings over the expected 20-year life of the installation are predicted to be nearly £850,000 ($1.3 million).

Novel Energy Lighting supplies the full range of Philips professional, specification, and trade LED products. Contact us to discuss your project needs today: T: 0208-540-8287, E: sales@novelenergylighting.com