Technical News

Field study of evacuation lighting In tunnels

Field study of evacuation lighting In tunnels
The purpose of the study was to test different characteristics of evacuation light. The study was carried out in a 40 foot long container and the fixtures were mounted approx. 1 meter above the floor and the study is based on a visual experience of the different light sources, and is considered a preliminary study of performance of evacuation lighting in tunnels.

The Norwegian Public Roads Administration will use this study together with other work to conclude on new improved regulations and specifications for evacuation lighting in tunnels.

The field test where carried out with the following light sources; Morrem LED evacuation light fixture with opal cover and clear coverage 120 degree lens and 3375K Ra 84. In addition, 4 types of LED evacuation light contiguous strips (white and green) that illuminate at about 1.4 W / m and 4.8 W / m 6089K Ra 89.3, and a strip of lights every 60 cm. The study was conducted as a collaboration between the Norwegian Tunnel Safety Cluster and their members, and the Norwegian Public Roads Administration.

The room was filled with smoke and through the experiment the smoke became gradually denser and denser. The study clearly showed that the smoke gradually became thicker the higher up the visual reading was performed. Only 20 cm height difference could be crucial when it comes to see the light at 3 - 4 meters distance. By moving closer to the light, it was possible to see the light at the height of 0.5 meter, even when the smoke was thickest and the light was adjusted down. Note that a test in a container, as in this case, will create a fresh air draft in the lower part of the container (floor area), and this effect can be different in a tunnel with fresh air draft from both sides.

The top light strip was first tested at full power 4,8 W (about 500 Lumen), then it was adjusted down to 1,4 W (about 150 Lumen) and at the end it lit on 2,4 W (about 250 lumen). About 200 lm / m appears to be a correct minimum amount of light for led stripes.

Further on the conclusions so far indicates that white light give better results than green light. Cover should also withstand up to approx. 200 degrees and must have flame retardant properties. When choosing material, note that a temperature difference of 10 degrees with a length of 125 m can give a significant expansion and must be taken into account when installing.

A LED strip can also act as a handrail and it must have a suitable dimension that should be defined.

We will follow up this article with further information when the final conclusions and recommendations are ready from the the study.


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