Design Aspects - Road Lighting: Fundamentals, Technology and Application - page 179

160 m

60 m

Fig. 13.1 T-shaped bright areas of two (axially-symmetrical light distribution) luminaires

- the light distribution of the luminaires (many road-lighting luminaires will, for
example, make the T-shaped pattern asymmetrical so that the road itself will
be brighter than the kerbside: compare Fig. 13.2 middle and left

• the overlapping of the luminance patterns of the different luminaires, which in

turn depends on:
- the installation geometry (lighting arrangement in terms of mounting height,
spacing and lateral luminaire position),
- the road geometry (road width).

The design process is, normally, carried out with the aid of lighting-calculation
software that accurately predicts the resulting luminance pattern and glare restriction
obtained for a given light distribution, road surface, installation and road geometry.
In those parts of residential areas where motorized traffic is allowed, the lighting
should be aimed at promoting road safety on the one hand and security and amenity
on the other. This means that the lighting quality parameters for both motorized
traffic and for pedestrians, cyclists and residents (as defined in Chap. 8 “Lighting
Quality Parameters”) should satisfy the requirements specified in Chap. 9 “Standards
and Recommendations”. Here it is the designer's task to not only cover the road
surface efficiently with light, but also to take care that the total space receives the
required amount of light as efficiently as possible (vertical or semi-cylindrical and/or
façade illuminance). Here, once again, the lighting-calculation software programs
are important tools for the lighting designer.