Lighting the different sections of tunnels

The advantages of appropriate lighting in tunnels

There are a great number of advantages to ensuring that tunnels have the right kind of lighting. In the first instance, lights help drivers’ eyes to adapt to the conditions as they enter and exit tunnels. They ensure that drivers are not affected by the significant differences between the light on the inside and on the outside.

Ultimately, this equals safety and visual comfort, although energy savings are also another driving force behind the installation of good lighting.

Driver safety

Delivering a quality lighting project means providing enough light at the entrance, exit and along the length of a tunnel to guarantee road traffic safety. Drivers need to be able to see potential obstacles in good time so that they do not have to brake suddenly as they travel. It is also important to avoid glare, which can happen if luminaires are not fitted in precisely the correct position or the light is too intense.

When it comes to tunnels, LED technology is safer than conventional high-pressure sodium devices. White lights, and not the yellow lights that were commonly used some years ago, are best.

Energy savings

Energy savings are another of the very attractive advantages of installing recommended tunnel lighting. LED technology can generate savings of around 70% compared with conventional lighting systems. In addition to keeping consumption as low as possible, this technology also comes with the guarantee of exactly the right level of brightness in each area. In other words, it is not just a question of consumption, it also about making tunnels safe and providing visual comfort for drivers.

Adhering to regulations

When it comes to tunnel lighting, adhering to regulations is an absolute must. The main applicable regulations for tunnels in Spain are:

• Directive 2004/54EC of the European Parliament and European Commission of 29 April 2004 on the minimum safety requirements for tunnels in the trans-European road network.
• RD 1890/2008 of 14 November.
• RD 635/2006 of 26 May on the minimum safety requirements for tunnels along the national road network.
• Directorate General for Highways Order 36/2015 on the criteria for lighting roads and tunnels.
• ‘Recommendations for lighting roads and tunnels’. The Directorate General for Highways (1999).

In addition to official regulations, there are guidelines and quality standards that focus on safety requirements and luminaire operation, including:

• ‘Guide for the lighting of road tunnels and underpasses’. CIE publication 88:2004.
• ‘Lighting applications. Lighting inside tunnels’. UNE-CR 14380:2007 IN.

Lighting each section of a tunnel

When it comes to designing lighting networks for tunnels, there are five main areas to take into account.

The entrance

This is the section just prior to the first few metres of a tunnel. As drivers approach, it is important for them to be able to see inside. In other words, they need to be able to see any obstacles up ahead without feeling the need to press the brake. The greatest challenge is ensuring that drivers’ eyes can adapt to the light inside the tunnel as quickly as possible.

The threshold

This section of tunnel is equal in length to the so-called breaking distance. Where it begins, the luminance must be steady and high-intensity and it must account for how much light there is on the outside. As drivers continue into the tunnel, the light decreases to under half the initial values.

The inside

This section of tunnel runs all the way from the transition zone to the exit and it is generally the longest section of all. Lighting in this area must be designed to account for the speed and density of traffic on the road.

The transition zone

Luminance decreases progressively along the transition zone until it reaches the appropriate level for inside the tunnel. This section of tunnel ends where luminance equals three times the level on the inside.

The exit

This is the section towards the end of the tunnel. In the daytime, a driver’s vision as he or she approaches the exit is determined by how bright it is outside. Unlike the circumstances when drivers enter tunnels, the human eye can adapt almost immediately when light changes from dim to bright.

However, extra light is needed in some cases. When the exit is not clear, it may be necessary to provide some sort of contrast either behind or in front of the driver. This should be 50 metres in length at most and the light should be five times stronger than on the inside.

Specialist Secom luminaires

Tunnel lighting systems need to be resistant because there tends to be a great deal of humidity, chemical and organic contaminants, fuel, oil, soot and dust in these environments. Tunnel luminaires are cleaned using a combination of pressure washers and strong cleaning products. Therefore, the luminaires installed in all areas of tunnels must be able to withstand the water pressure and products and function without the need for constant cleaning and maintenance work.

The illumination on roads and in tunnels must meet a number of recommendations and only quality luminaires can deliver acceptable results.

Tunnel luminaires by Secom

The Secom product catalogue is wide-ranging. One option is the Esdium Tunnel HE, an exterior lighting system that is perfect for tunnels. It comes with all the safety, durability and visual quality guarantees.

Secom success stories

Secom is a leading provider of tunnel lighting. The following are just some of its top projects:

• The Eysturoy tunnel (Norwegian Sea). This tunnel links several islands to the mainland.
• The tunnel in Palma de Mallorca. This tunnel is runs through the Alfabia mountain range between Sóller and Palma de Mallorca.

Tunnel lighting must meet a number of different objectives and account for several requirements. When it comes to tunnel lighting, Secom products are exactly what you need.

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