Safety and visual comfort in tunnels and passageways
The requirements for lighting planning and lighting solutions in tunnels and passageways are particularly demanding. The luminaires must satisfy the toughest demands for reliability, ease of maintenance and light quality in order to guarantee the safety and smooth flow of traffic. This depends on the physical comfort of car drivers and is influenced significantly by the lighting quality. Good lighting means greater relaxation at the wheel, enhanced driving safety, a constant driving speed and a harmonious flow of traffic.
Helping the human eye adapt to changing light is one of the most important tasks of tunnel lighting. The lighting must make the abrupt transition from bright light at the tunnel entrance to the dark environment inside the tunnel more pleasant by introducing a very high level of illumination at the tunnel entrance area and subtly adjusting the illumination towards the center of the tunnel. In order to eliminate the uncomfortable feeling of enclosed spaces, the illumination levels within tunnels are somewhat higher than with street lighting for open roads. Lateral continuous rows give a homogeneous light distribution and avoid flickering effects as drivers travel through. They also create a directional optical effect.
Additional requirements may arise as a result of specific conditions in the tunnel that do not occur in a technical street lighting environment. A high concentration of pollutants, dust, extreme temperatures and moisture create an atmosphere that only the most durable structures can withstand. Since the lighting in tunnels operates 24 hours a day, durable low-maintenance solutions are required to minimize the number of interruptions in operation.