HAGNER Tunnel Entrance Photometer
MODEL TLS-420 (INCL. TLS-420/S & TLS-420/SW)
The Hagner TLS-420 Tunnel Entrance Photometer is designed to measure the average luminance of road tunnel
entrance and its surroundings according to CIE recommendations and is used, together with a PLC/computer, to
regulate the lighting inside the tunnel. The idea is to control the illumination inside the tunnel to a level
corresponding to the degree of light adaptation of an approaching cardriver´s eyes.
Introduction
The aim of road tunnel lighting is to ensure that traffic, both during daytime and night time, can approach, pass
through and leave a tunnel, at the designated speed, with a degree of safety and comfort not less than along the
adjacent stretches of open road.
In daytime it is essential that appropriate luminance has been provided in the threshold zone (the first stretch of
the entrance) of the tunnel to avoid the driver experiencing “the black hole effect”. A hazardous situation is
created if a lack of visibility suddenly causes the driver to reduce speed. The required luminance depends on the
luminance to which the approaching car driver’s eyes are adapted. Studies show that to a large extent this
adaptation depends on the luminance in and around the tunnel entrance.
According to CIE (Commission Internationale de l’Eclairage) recommendations this luminance can be measured
as the luminance contained in a conical field of view, subtending an angle of 20 o It is normally recommended that
the measurement is made at a distance from the tunnel entrance which is equivalent to the stopping distance for
a vehicle approaching the tunnel.
(I.e. the distance depends on factors such as the speed on the road, its slope, its condition etc). Other factors can
also influence the measuring distance. (For further information see CIE publications No 61 (1984) and No 88
(1990).)
The Hagner TLS-420 Tunnel Entrance Photometer is designed to measure the average luminance of a tunnel
entrance and its surroundings as to CIE recommendations. The photometer measures the average luminance
within a cone with a top angle of 20 o (other measuring angles can be provided on request), by means of a
detector carefully filtered to give a spectral response close to that of the human eye, as defined in CIE standards.
The photometer has an output of 4 – 20 mA DC for a luminance range 0 – L cd/m 2 where ”L” is chosen by the
customer when ordering the photometer. A common value of ”L” is 6,500 cd/m 2
The 4 – 20 mA output makes the TLS-420 suitable for computerized systems and also makes it possible for the
output signal to be transmitted over great distances. (Max external resistance is 800 ohm.)
As an important part of the system B Hagner AB offers a ready programmed PLC computer for regulating the
tunnel lighting, with switching levels (up to 10 levels each for 2 separate Tunnel Photometers plus 2 alarm levels)
and time delays set according to the customer requirements. When delivered with a Display Panel the customer
can easily change the pre-set values, if required.
The Photometer is mounted in a waterproof, thermostat housing made in stainless steel (or aluminium). The front
glass can be provided with automatic cleaning equipment. The power supply is 220 – 240V AC.
Part No
1) Hagner Model TLS-420/S (without wiper) Tunnel Entrance Photometer
2) Hagner Model TLS-420/SW (with built-in wiper) Tunnel Entrance Photometer
3) Hagner Model WW1/5 – windscreen washer
4) Hagner Model SW/S – Adjustable mount
5) Hagner Model CSS-1 – Wall bracket
6) Hagner Model EH-150 – PLC computer inclusive of program
7) Hagner Model Sight 400 – Sight for TLS-420
