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Author ：Green earth– LED Strip Lights manufacturers
In the US Road Lighting Design standard, the road is divided into six categories according to the road complexity and traffic volume. For each type of road, it is different from the different and third-speed size of the traffic material in the road reflective material. Evaluation indicator specified. IESNA proposes three types of road lighting evaluation indicators, and designers can choose the appropriate indicators as needed. These three types of indicators are illumination index (including average illumination and illuminance uniformity), brightness indicators (including average brightness, brightness uniformity and brightness uniformity) and small target visibility indicators. Among the illumination index and brightness indicators contain light-curtain luminance ratio indicators for glare.
According to CIE and IESNA, two types of road lighting design standards can be obtained by two types of standard motor lane lighting design standards mainly reflected in the following three points:
1. Evaluation indicators.
CIE mainly uses brightness indicators to evaluate, including threshold increment Ti and environment than SR indicators; and IESNA uses three indicators, metrics, brightness indicators, and small target visibility indicators STV, where illuminance indicators and brightness indicators are used. The light curtain brightness ratio indicators are included to evaluate glare.
2. Calculation method of evaluation index.
The main difference is reflected in the calculation of brightness indicators, and CIE specifies only one observer on each lane, and is fixed to 60 meters in the calculation area start position, observe all of the matrix points in a luminaire period (as shown in Figure 1 Show); IESNA specifies that each line of matrix points in the calculation area have a observer, and each observer always observes the brightness of the matrix point of 83 meters in front of the matrix (shown in Figure 2), meaning IESNA. The observer in the standard not only does the lateral movement in the direction of the lane, but also performs longitudinal movement in the direction of the parallel lane.