Traffic signal duration

Figure 25.17 LED arrays in traffic signals. Many communities have replaced the red and green signals with LED arrays that are much more energy efficient than the incandescent bulbs used previously. The yellow lights are being replaced more slowly, however, because LED arrays are expensive and the short duration of yellow lights would not neces.sarily allow an overall cost saving when the energy efficiency IS factored in.

But the duration of the traffic signal light is only an indirect measure of delay. To assess the effects of delay at the signal more directly, in a followup study we observed forty traffic lights with varying durations, half in a fast-paced city (Tel Aviv) and half in a slow-paced city (Beer... 

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