Standards and Recommendations - Road Lighting: Fundamentals, Technology and Application - page 104

Table 9.8 Example of adaptive lighting classes for different time periods. Based on different
weighting values V w for the parameter “traffic volume”
Parameter

Options Description V w V w selected

%of
maximum
capacity

17:00 20:00 20:00

23:00

23:00
05:30

05:30
09:00

Traffic volume Very high > 45 1 1 1

Moderate 15-45 0 0

Very low < 15 − 1 − 1

VWS sum of
other parameters

3 3 3 3

VWS total sum 4 3 2 4

M = 6 − VWS M2 M3 M4 M2

9.2.4 Spectrum of Light

The draft European Standard contains no specifications for the light spectrum, colour
temperature or the colour rendering index of the light sources used. All lighting-level
specifications of the Standard are independent of the spectrum.

9.2.5 Adaptive Lighting

The EN standard explicitly mentions adaptive lighting. The traffic characteristics
that determine the lighting quality required, as defined by the weighting values, may
vary during the course of the evening and night. This may permit of periods with
reduced lighting level. The standard stresses the importance of using the weighting
tables for this purpose. An illustration of this is given in Table 9.8 .Itisforatwo
lane traffic route that corresponds to an M2 lighting class, where the traffic volume is
pronouncedly different at different time intervals in the evening and night. The table
shows the part of the weighting table of the European standard that corresponds to
the parameter “traffic volume”.
The sum of the weighting values for the M2 class is 4 and is, in this example,
relevant for the time intervals 17:00-20:00 ⓦ h and 05:30-09:00 h. Because of the
lower traffic volumes for the time intervals from 20:00 to 23:00 ⓦ h (weighting factor:
0) and from 23:00 to 05:30 ⓦ h (weighting factor:

1) the M class changes for the
corresponding time intervals from M2 to M3 and M4 and back to M2. According to
the European standard, M2 requires a lighting level of 1.5 cd/m 2 , M3 of 1.0 cd/m 2 and
M4 of 0.75 cd/m 2 . So if indeed the lighting installation can be switched or dimmed to
these lower levels, considerable savings are possible with such an adaptable lighting
system. Care should be taken that while adapting the lighting level, the uniformity
values are not affected.

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