Making tunnel lighting more sustainable

The installations in Rijkswaterstaat’s tunnels consume more than 40 million kWh of electricity each year. Approximately half of this is used for lighting. Studies and tests show that there are various possibilities for reducing the energy consumption for lighting in tunnels. This was reason enough for the COB to start a research program together with network parties, including Rijkswaterstaat. The COB is looking for tunnel projects at home and abroad to carry out this research program. Interested parties can apply to the COB for one of the fourteen research projects.

Until a few years ago, gas-discharge lamps, such as high-pressure sodium (HPS) lamps with their characteristic orange light color, were used to illuminate tunnel tubes. LED lamps have now become the norm. Tunnel managers are switching to these energy-efficient lights both for new tunnels and when renovating existing tunnels. By using LED lighting, energy savings of 10 to 20 percent have been achieved.

Based on practical tests and the characteristics of LED lamps, experts assume that even higher energy savings are possible. The Dutch National Tunnel Standard (LTS) currently requires the light level in tunnels to be determined on the basis of the Tunnel Lighting Guidance issued by the Dutch Foundation for Illumination (NSVV: Nederlandse Stichting voor Verlichtingskunde). This guidance is based on gas-discharge lamps and does not yet take into account the wider light spectrum of LED lamps. If research shows that the light level of LED lamps can indeed be reduced, the guideline will have to be amended.

Potential for savings

  • LED lamps have a considerably wider light spectrum than gas-discharge lamps. As a result, at the same lighting level, the light from LED lamps is experienced as brighter than that from gas-discharge lamps. The expectation is therefore that the light level of LED lamps can be lowered while the perception remains the same.
  • LED lamps are also easy to dim and the light level can be adjusted to changing circumstances much more quickly. This includes adjusting the lighting level to the amount of light outside the tunnel, to the actual traffic intensity, or the actual speed of the traffic. This, too, offers opportunities for savings.
  • Reducing the lighting level in the central part of the tunnel in long tunnels is also worth investigating.
  • Improving the adjustment and maintenance of the so-called L20 meter, which measures the amount of light just before the tunnel entrance and determines the level of the entrance lighting on that basis, is also worth investigating.
  • The use of lighter, reflective asphalt and bright walls can also lead to savings.

Knowledge and experience from previous studies

In recent years, various research projects and trials have already been carried out to identify the savings potential of LED lighting. During the renovation of the Velsertunnel, for example, a road test was carried out with lighting experts, in which the basic lighting in the tunnel was dimmed. The participants were asked whether they could see enough to drive through the tunnel and whether they could still see objects on the road surface. One of the results was that participants did not notice it when the light level was dimmed to 70% of the prescribed level. And it was only when the lighting level was reduced by 50% that they could no longer see the objects clearly, but they could still see enough to drive through the tunnel.

After the Velsertunnel, tests have been carried out in the Mont Blanctunnel, the Gaasperdammertunnel, and the Ketheltunnel. These tests all subscribe to the potential savings for modern lighting systems.

Tests in de Mont Blanctunnel (photo: COB/Harry de Haan).

COB research program

The above studies and tests show that there are various possibilities for further reducing the energy consumption of tunnel lighting. However, additional research is needed to better substantiate and further concretize the various options. For example, to see if the savings measures also work in other tunnels. The COB has developed a research program for this, together with several parties, including Rijkswaterstaat.

The COB is looking for tunnel projects at home and abroad to carry out this research program. Interested parties can apply to the COB for one of the fourteen research topics.

  1. Reducing light levels in basic lighting and entrance lighting
  2. Reduction of the basic lighting level in long tunnels
  3. Dynamic control of light level in the entrance area based on actual speed
  4. Smoother progression of the CIE curve
  5. Application of new curve for eye sensitivity in light measurements
  6. Use of highly reflective asphalt
  7. Controlling basic lighting according to traffic intensity and speed
  8. Better monitoring of tunnel lighting control
  9. Limiting the lighting level by counteracting glare
  10. Making the tunnel entrance greener
  11. Improving L20 measurements
  12. The ratio of reflection of walls and road surface
  13. Advantages of line lighting compared to point lighting
  14. Direct current tunnel lighting

 

Attendees

COB

Locatie: Delft, Van der Burghweg 2
Karin Clement, rol: Begeleider/Facilitator

Croonwolter&dros

Locatie: Rotterdam, Marten Meesweg 25
Dennis Makkus, rol: Lid
Hans Pos, rol: Lid

DON Bureau

Locatie: Bergen Op Zoom, Prins Bernhardlaan 64
Tom van Tintelen, rol: Lid

Elumint B.V.

Locatie: Zoetermeer, Lenastroom 3
Harry de Haan, rol: Projectleider

Heijmans Infra B.V.

Locatie: Rosmalen, Graafsebaan 67
Huib Arts, rol: Lid

Rijkswaterstaat GPO

Locatie: Utrecht, Griffioenlaan 2
Gioffry Maduro, rol: Coordinator
Johan Naber, rol: Lid