As our road networks become more crowded, the use of tunnels and underpasses is expanding, both to improve traffic flow, and to protect local environments from increased traffic exposure.
Within tunnels, where maintenance access can be limited, and where corrosive atmospheric conditions are common, reliable performance of the lighting system is critical, as is the need for the absolute minimum of operational maintenance requirements.
The objectives of tunnel lighting
The aims of tunnel lighting are:
•Firstly, to allow traffic to enter, pass through and exit the enclosed section safely
•Secondly, to do so without impeding the through-flow of traffic. These aims are achieved by the adequate illumination of the tunnel interior, which allows drivers to quickly adjust to the light within, identify possible obstacles, and negotiate their passage without reducing speed.
These requirements apply during the day when the contrast between outside and inside is significant and at night when it is less, but reversed.