Equipment and Design Aspects - Road Lighting: Fundamentals, Technology and Application - page 300

Chapter 22
Equipment and Design Aspects

Abstract For the high lighting levels in the threshold zone, pronounced light distri-
butions in the longitudinal direction are needed, which calls for the use of compact
lamps. Tubular high-pressure sodium lamps and LEDs are therefore the lamp types
most suitable for the lighting of the threshold zone. For the tunnel zones, where
lower lighting levels are needed, viz. the transition and the interior zone, long linear
light sources are more advantageous. Many tunnels therefore make use of tubular
fluorescent lamps for these zones. However, thanks to the high efficacy and long life
of LEDs, these types today offer often a more efficient solution. The most important
properties of these lamps and of the luminaires in which they can be used, will be
dealt with in this chapter. Daylight screens mounted in front of the tunnel that fil-
ter the daylight, can sometimes be an alternative to electric daytime lighting of the
threshold zone. Such screening equipment will also be discussed in this chapter.
The importance of appropriate reflection properties of both the road surface and
the lower parts of the walls will also be considered.
Also in this chapter, those design aspects that specifically relate to tunnel lighting
design will be discussed. This concerns not only guidance for the lighting arrange-
ments, but also for a proper control and maintenance of the installation. The tools to
determine the values of L 20 and L seq , needed to define the required lighting levels of
the threshold and consecutive tunnel zones, are also described.

22.1 Lamps and Gear

Figure 22.1 groups those lamps used for tunnel lighting according to the technology
involved. Table 22.1 gives a survey of the values of the more important properties of
these lamps. The values given are representative for the wattage versions commonly
employed in tunnel lighting. Where relevant, the values of the properties include the
effect of the electrical gear (Table 22.1 ).
For the high lighting levels in the threshold zone, lamps with both a high luminous
efficacy and a high lumen output are required. This makes the high-pressure sodium
lamp suitable for the lighting of the threshold zone. It has a somewhat lower efficacy
than that of the low-pressure sodium lamp, but its luminous flux is higher and the
lamp is more compact, so permitting of a pronounced, sharp-beam light distribution
from a smaller luminaire. This combination of properties means that fewer luminaires