Forums Forums Traffic Signals Optimum PECU lux levels for traffic signals

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  • #1041
    Power Data

    In our role as Meter Administrator we have visibility of the different PECUs used on the traffic signal installations by our customers. These codes identify the type of photocell used to control the bright/dim function in traffic signals. I have never really understood if there is an optimum lux level range for a set of traffic signals, we have a very wide variation across our customer base:

    411 Thermal PEC 55/110
    421 Thermal PEC 70/140
    431 Thermal PEC 100/200
    621 Hybrid PEC 70/35
    807 Electronic PEC 35/35
    808 Electronic PEC 35/18
    811 Electronic PEC 55/28
    821 Electronic PEC 70/35
    824 Electronic PEC 70/140
    831 Electronic PEC 100/50

    The higher lux cells mean that the traffic signals are dim for longer (=lower annual energy use) than the lower lux cells that turn to bright earlier in the morning. But energy is probably not the key driver, the key driver is safety to ensure they are bright enough to be seen at dawn/dusk whilst not dazzling the driver by being bright too late into dusk.

    Is there any official industry guidance or advice on the appropriate lux levels to use?

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