Page 33 - TT July Issue for Digital Edition

ROAD SAFETY

Tunnel Lighting –
For comfort, safety

and visual performance

Tunnel lighting requirements differ from road lighting in that they must address
sudden changes in brightness over critical lengths, while road lighting mainly
focuses on night visibility. In the majority of tunnels, the natural penetration of

light does not allow satisfactory visibility for users. It is therefore necessary to
install artificial lighting to improve visibility and comfort.

he International influenced by the brightness In terms of functionalities, the
Commission on outside the tunnel. lighting installation must allow
Illumination (CIE) Motorists approaching a tunnel for normal lighting that provides
standards requires that appropriate visibility for users during
the amount of light within entrance experience what is both day and night, safety lighting
Ta tunnel is dependent on known as the “black hole effect”. that provides minimum visibility
the level of light outside and This is because luminance levels for users to enable them to leave
on the point inside the tunnel inside the tunnel are much lower the tunnel in their vehicles in case
at which visual adaptation of than those outside and the eyes of power outage and evacuation
the user must occur. There are have difficulty adapting to the lighting to guide tunnel users on
five key areas to consider while sudden difference. To alleviate foot in the event of an emergency.
illuminating the tunnel. The this effect, a higher, “reinforced”
Access Zone which is not within level of lighting is at the tunnel Traveling through tunnels can
the tunnel itself but the stretch entrance. This will ensure that be both a thrilling experience
leading to its entrance. From this drivers can see objects within and a visual treat. Sydney’s nine-
zone, drivers must be able to see the correct stopping distance kilometre long NorthConnex
into the tunnel in order to detect before entering the tunnel. It will motorway tunnel boasts artwork,
possible obstacles and to drive also help to prevent them from changing visual displays and
into it without reducing speed. slowing down, which is important unique lighting features to keep
The second is the Threshold zone to maintain optimal traffic flow. drivers engaged as they travel.
which is equal in length to the In order to enable drivers’ eyes The lighting displays were installed
‘stopping distance’. In the third to adapt from the entrance zone after extensive research to help
Transition zone, luminance is lighting to the interior zone keep drivers alert and engaged
reduced progressively to reach lighting, the entrance lighting level and the tunnel is equipped with
the Interior or fourth zone which is gradually reduced as drivers innovative, advanced LED lighting
is often the longest stretch of move along the tunnel. Once to ensure motorists can safely
the tunnel. The fifth and final is drivers have adapted to the lower transition from bright daylight to
the Exit zone and, in this zone, luminance levels in the tunnel, the darker interior tunnel section.
during the day, the vision of a sufficient lighting is needed in the Content sourced from
driver approaching the exit is interior zone for safe passage. articles on tunnel lighting TT

www.trafficinfratech.com / July 2024 / TRAFFICINFRATECH 33