The luminance value of the interior zone is the major difference
between the CIE 88:2004 and the UNI 11095. The former does
not set an objective luminance value, while the Italian standard
establishes a minimum value.
The luminance in the exit zone is equal to Li or may increase to
improve the visual comfort.
Fig. 2 shows the luminance curve calculated for tube A. The
threshold luminance is 149 cd/m2. The curve has been calculated
using the observer-variable method, which ensures the maximum
energy saving. Due to the relatively short length of tunnel, the
transition luminance value does not reach the interior luminance
value.
Fig. 3 shows the illuminance curves associated with the
luminance curve of Fig. 2. Each illuminance curve represents the
illuminance of the tunnel with concrete or asphalt pavement.
The supposed reflective coefficient of wall is equal to 50%.
A permanent lighting circuit and a reinforcement lighting
circuit set up the lighting installation. Luminaries are arranged
with a quincunx geometric pattern; their spacing is calculated to
avoid the Flicker effect.
The used PROLITE 7.0 program is a professional lighting
simulation software edited by Gewiss, which allows modelling
and verifying the lighting design of road tunnels. It provides
numeric and rendered solutions simulating the effects of lighting
(shadows, reflections, color vision and rendering volumes) and
achieving the lighted picture environment.
As regards the calculation, the maintenance coefficient is equal
to 0.9, the average luminance coefficient is 0.07 for asphalt pavement
and 0.1 for concrete pavement, according to the UNI
10439:2001 standard.
Table 5 represents the geometrical characteristics of luminaries
assumed to verify the lighting system in the case of concrete and
asphalt pavement.