Standards and Recommendations - Road Lighting: Fundamentals, Technology and Application - page 296

Fig. 21.2 Daytime lighting
requirement for short tunnels.
(CIE 2004 )

length < 25 m 25 - 75 m 75 - 125 m > 125 m

exit visible yes no yes no

daylight
penetration

good poor good poor

reflectance
walls

high low high low

light heavy light heavy

traffic

50 %
threshold zone
lighting

100 %
threshold zone
lighting

no daytime
lighting

• whether the wall reflectance is high ( > 0.4) or low ( < 0.2),

• whether or not traffic is heavy or includes cyclists or pedestrians.

The requirement for the lighting in accordance with these requirements varies from
“no daytime lighting required” or “fifty per cent of normal threshold-zone light-
ing level required” to “normal threshold zone lighting level required”. The normal
threshold zone lighting here is that required for long tunnels. Figure 21.2 indicates
which combination of the above factors leads to which lighting requirement.

21.2 European Report

The European Committee for Standardization (CEN) has not yet published a Standard
on tunnel lighting. In 2003 CEN published a report that covers some common aspects
of tunnel lighting and describes some different methods currently in use or under
consideration in some European countries (CEN 2003 ). Most methods discussed are
based on research dealt with already in Chap. 20 of this topic. No single method
is recommended in the report. Since it is not the intention here to discuss national
Standards and Recommendations no further details of the CEN report will be given
here.