The TunnelTech 601 Luminance photometer monitors the average luminance of a tunnel entrance and its surroundings.
The TunnelTech 601 Luminance photometer monitors the average luminance of a tunnel entrance and its surroundings. In accordance with Commission Internationale de l´Eclairage, (C.I.E.), publication 88, 1990 recommendations, the photometer monitors the average luminance within a 20-degree angle over a standard range of 0 - 6,500 cd/m2.
The detector is a metal/glass encased silicon diode photocell which is filtered to give a response that mimics the performance of the human eye. The detector is perfectly linear within its measuring range and has an instantaneous response to changing light levels.
According to CIE recommendations luminance should be monitored as the luminance contained within in a conical field of view, subtending an angle of 20º. It is recommended that the luminance photometer is mounted in the tunnel approach road approximately 120 - 200 meters from the portal, depending on the approach speed of the vehicles and their stopping distance.
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