Lighting applications - Tunnel lighting

This standard is valid for all road tunnels and underpasses which are used by the motorised traffic, and which are decided to be lighted.

Eclairagisme - Eclairage des tunnels

Uporaba razsvetljave – Razsvetljava v predorih

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SIST-TP CR 14380:2004
Uporaba razsvetljave – Razsvetljava v predorih
Lighting applications - Tunnel lighting
Eclairagisme - Eclairage des tunnels
Ta slovenski standard je istoveten z: CR 14380:2003
93.060 Gradnja predorov Tunnel construction
93.080.40 &HVWQDUD]VYHWOMDYDLQ Street lighting and related
SIST-TP CR 14380:2004 en
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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SIST-TP CR 14380:2004

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SIST-TP CR 14380:2004
CR 14380
April 2003
English version
Lighting applications - Tunnel lighting
This CEN Report was approved by CEN on 10 November 2001. It has been drawn up by the Technical Committee CEN/TC 169.
CEN members are the national standards bodies of Austria, Belgium, Czech Republic, Denmark, Finland, France, Germany, Greece,
Hungary, Iceland, Ireland, Italy, Luxembourg, Malta, Netherlands, Norway, Portugal, Slovakia, Spain, Sweden, Switzerland and United
Management Centre: rue de Stassart, 36  B-1050 Brussels
© 2003 CEN All rights of exploitation in any form and by any means reserved Ref. No. CR 14380:2003 E
worldwide for CEN national Members.

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SIST-TP CR 14380:2004
CR 14380:2003 (E)
0 Introduction . 6
1 Scope . 6
2 References. 6
3 Definitions. 6
3.1 Tunnel related zones
3.2 Lighting
3.3 Luminances, illuminances
3.4 Traffic related concepts
4 General aspects of tunnel lighting. 10
4.1 Tunnel conditions
4.1.1 Stopping Distance
4.1.2 Tunnel Lighting Requirements
4.1.3 Traffic composition
4.1.4 Road and Tunnel conditions
4.2 Distinction between long and short tunnels
4.3 Lighting systems and contrast rendition methods
4.3.1 Artificial lighting systems
4.3.2 Screened daylight systems
4.4 Aspects common to the various design methods
4.4.1 Flicker
4.4.2 Glare restriction
4.4.3 Lighting control
4.4.4 Maintenance
5 Lighting of long tunnels. 18
6 Artificial lighting of short tunnels and underpasses . 18
7 Emergency lighting. 19
8 Traffic signals. 19
9 Measurement of tunnel lighting installations . 19
9.1 Quality numbers for tunnel lighting installations
9.2 Measuring fields
9.3 Instruments and methods
9.3.1 General
9.3.2 Illumination measurements
9.3.3 Luminance measurements with spot-luminancemeter
9.3.4 Reflection measurements

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SIST-TP CR 14380:2004
CR 14380:2003 (E)
A.1.1 Luminance level in the threshold zone
A.1.2 Length of the threshold zone
A.1.3 Lighting requirements for the transition zone
A.1.4 Lighting of the interior zone
A.1.5 Lighting of the walls
A.1.6 Uniformity of the road surface luminance
A.1.7 Lighting of the exit zone
A.1.8 Night time lighting
A.1.9 Glare and flicker
A.1.10 Determination of the luminance in the access zone
A.1.10.1 Approximation of L20
A.1.10.2 Determination of L20
A.2.1 The determination of the tunnel class
A.2.2 The lighting of the threshold zone of long tunnels
A.2.3 The length of the threshold and transition zone
A.2.4 The road surface luminance of the interior zone
A.2.5 The exit zone
A.2.6 Non-uniformity of the luminance
A.2.7 The lighting of the tunnel walls
A.2.8 Glare restriction
A.2.9 Restriction of the flicker
A.2.10 Night-time lighting
A.3.1 Introduction
A.3.2 The determination of the required contrast in the threshold zone of a long tunnel
A.3.3 The veiling luminance Lv
A.3.3.1 The determination of the veiling luminance Lv
A.3.3.2 The determination of Lseq
A.3.3.3 The determination of Latm
A.3.3.4 The determination of Lwinds
A.3.4 The determination of the threshold zone luminance
A.3.5 Object and road luminance
A.3.5.1 No daylight influence
A.3.5.2 The influence of daylight falling into the tunnel at the tunnel entrance
A.3.6 Further tunnel lighting design aspects
A.3.6.1 The threshold zone
A.3.6.2 The lighting of the transition zone
A.3.6.3 The lighting of the interior zone and the exit zone of long tunnels
A.3.6.4 Glare restriction
A.3.6.5 Restriction of the flicker

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A.4.1 The principle of the method
A.4.2 The luminaire adaptation
A.4.3 The space adaptation
A.4.4 The time adaptation
A.4.5 Characterising the lighting installation
A.4.6 Calculating road luminance
A.4.7 Algorithm of LCR calculations
A.4.8 Calculation details for one 10 meters step for a rather simple case
A.4.9 Calculating illuminance levels
A.4.10 The results
A.4.11 Road surface luminance of the interior zone at day-time
A.4.12 Night-time lighting
A.4.13 Lighting of the walls of the interior zone
A.4.14 Emergency guidance lighting
A.4.15 Fire emergency guidance lighting
A.4.16 Uniformity of the road surface luminance
A.5.1 Determination of the look through percentage
A.5.2 Using the look through percentage
A.5.3 Influencing the look through percentage
A.5.4 Daytime lighting of short tunnels
A.5.5 A table method for determining the need of artificial daytime lighting

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SIST-TP CR 14380:2004
CR 14380:2003 (E)
0 Introduction
The aim of tunnel lighting is to ensure that users, both during the day and by night, can approach, pass through,
and exit the tunnel without changing direction or speed with the degree of safety commensurate to that on the
approach road.
To achieve safe passage through a road tunnel, it is necessary that all users have sufficient information regarding
the course of the road ahead, possible obstacles and the presence and actions of other users. Furthermore it is
necessary that users,particularly drivers of motor vehicles, have at least an equal sense of security to that
experienced on the approach roads.
Principal characteristics required to describe the quality of tunnel lighting are:
– the luminance and illuminance levels of the road surface;
– the luminance level of the walls up to 2 m in height above the road surface;
– the uniformity of the luminance distribution on the road and walls;
– the control of induced glare;
– the avoidance of critical flicker frequencies.
1 Scope
This CEN Technical Report gives guidance on the design of the lighting of road tunnels and underpasses for
motorized and mixed traffic. This guidance concerns arrangements, levels and other parameters including daylight,
which are related only to traffic safety. Aspects concerning visual comfort should be chosen in agreement with
national practice. The guidance in this report may be applied to any tunnel or underpass where the decision to
provide lighting has been taken by any authority working within national legislation or other constraints. The report
is based on photometric considerations, and all values of luminance and illuminance are maintained values.
The main body of the report covers the common aspects of Tunnel Lighting, and the various methods currently in
use in Europe are detailed in the annexes. No single method is recommended.
2 References
This Technical reports incorporates by dated or undated reference, provisions from other publications. These
references are cited at the appropriate places in the text and the publications are listed in appendix. For dated
references, subsequent amendments to or revisions of any of these publications apply to this Technical Report only
when incorporated in it by amendment or revision. For undated references the latest edition of the publication
referred to applies.
Not applicable
3 Definitions
For the purposes of this document, the definitions of prEN12665 and prEN13201 and the following apply. The
definitions of zones in a tunnel are based on lighting considerations and not on aspects of installation technique
or on civil engineering. The lighting terms are in agreement with the CIE Publications.

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3.1 Tunnel related zones
3.1.1 entrance portal: the part of the tunnel construction that corresponds to the beginning of the covered part of
the tunnel or, when open sun-screens are used, to the beginning of the sun-screens.
he end of the covered part of the tunnel or, when open sun-screens are used, to the end of the
3.1.2 exit portal: t
3.1.3 access zone: the part of the open road immediately outside (in front of) the tunnel portal, covering the
distance over which an approaching driver should be able to see into the tunnel.
3.1.4 access zone length : the access zone begins at the stopping distance point ahead of the portal and ends
at the portal.
the first part of the tunnel, directly after the portal. The threshold zone begins at the portal.
3.1.5 threshold zone:
3.1.6 transition zone: the part of the tunnel following directly after the threshold zone. The transition zone
stretches from the end of the threshold zone to the beginning of the interior zone. In the transition zone, the lighting
level is decreased from the level at the end of the threshold zone to the level of the interior zone.
3.1.7 entrance zone: the combination of the threshold zone and transition zones.
3.1.8 interior zone: the part of the tunnel following directly after the transition zone. The interior zone stretches
from the end of the transition zone to the beginning of the exit zone.
3.1.9 exit zone: the part of the tunnel where, during day-time, the vision of driver approaching the exit is influenced
predominantly by the brightness outside the tunnel. The exit zone stretches from the end of the interior zone to the
exit portal of the tunnel.
3.1.10 parting zone: the first part of the open road directly after the exit portal of the tunnel. The parting zone is
not a part of the tunnel, but it is closely related to the tunnel lighting. The parting zone begins at the exit portal.
3.2 Lighting
the optical and geometrical means that ensure that motorists are given adequate informa-
3.2.1 visual guidance:
tion on the course of the road in the tunnel.
3.2.2 threshold zone lighting: lighting of the threshold zone of the tunnel which allows drivers to see into the
tunnel whilst in the access zone.
3.2.3 transition zone lighting: lighting of the transition zone which facilitates the drivers' visual adaptation to the
lower level in the interior zone.
lighting of the interior zone of the tunnel which provides adequate visibility in the
3.2.4 interior zone lighting:
interior of the tunnel, irrespective of the use of vehicle headlights.
3.2.5 exit zone lighting: lighting of the exit zone which improves the visual performance during the transition from
the interior zone to the open road beyond the tunnel.
3.2.6 emergency lighting: lighting provided for use when the supply to the normal lighting fails. [prEN 12665]

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3.2.7 fire emergency guidance lighting: lighting providing visual guidance in the event of fire and smoke.
3.2.8 daylight screens, louvres: devices that transmit (part of) the ambient daylight. They may be applied for the
lighting of the threshold zone and/or the entrance zone of a tunnel.
screens that are designed in such a fashion that direct sunlight cannot reach the road
3.2.9 sun-tight screens:
surface under the screen.
3.3 Luminances, illuminances
3.3.1 access zone luminance : the eye adaptation luminance in the access zone.
3.3.2 L20 access luminance : average luminance contained in a conical field of view, subtending an angle of
20 ° with the apex at the position of the eye of an approaching driver and aimed at the centre of the tunnel mouth.
L is assessed from a point at a distance equal to the stopping distance from the tunnel portal at the middle of the
relevant carriage-way or traffic lane.
3.3.3 equivalent ocular veiling luminance (Lseq): the light veil as a result of the ocular scatter L is quantified
as a luminance.
3.3.4 atmospheric luminance (Latm): the light veil as a result of the scatter in the atmosphere expressed as a
3.3.5 windscreen luminance (Lwinds): the light veil as a result of the scatter in the vehicle windscreen expressed
as a luminance.
3.3.6 threshold zone luminance (L ): the average road surface luminance of a transverse strip at a given
location in the threshold zone of the tunnel (as a function of the measurement grid).
the average road surface luminance of a transverse strip at a given location
3.3.7 transition zone luminance (L ):
in the transition zone of the tunnel (as a function of the measurement grid).
3.3.8 interior zone luminance (L ): the average road surface luminance of a transverse strip at a given location
in the interior zone of the tunnel (as a function of the measurement grid).
3.3.9 vertical illuminance (E ): the illuminance at a particular location at a height of normally 0,1 m above the
road surface, in a plane facing the direction of oncoming traffic. The height of 0,1 m above the road surface is meant
to represent the centre of an object of 0,2 m x 0,2 m.
3.3.10 contrast revealing coefficient (q ): the quotient between the luminance of the road surface, and the vertical
illuminance E at that point.
q =
-2 -1
where q is the contrast revealing coefficient in cd.m lx

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3.3.11 threshold zone luminance ratio (k) at a point: the ratio between the threshold zone luminance L and the
access zone luminance L .
k =
3.3.12 overall uniformity (of road surface luminance, wall surface luminance) (U ): ratio of the lowest to the
average luminance on the reference field of calculation or measurement.
ratio of the lowest to the
3.3.13 longitudinal uniformity (of road surface luminance of a carriageway) (U ):
highest road surface luminance found in a line in the centre along a driving lane. The longitudinal uniformity is
considered for each driving lane.
3.3.14 veiling luminance (Lv): the luminance that, when added by superposition to the luminance of both the
adapting background and the object, makes the luminance threshold or the luminance difference threshold the same
under the two following conditions:
– glare present, but no additional luminance;
– additional luminance present, but no glare.
3.4 Traffic related concepts
that part of the road normally used by vehicular traffic.
3.4.1 carriageway:
a strip of carriageway intended to accommodate a single line of moving vehicles.
3.4.2 traffic lane:
a lane parallel to the traffic lane(s), not destined for normal traffic, but for
3.4.3 emergency lane (hard shoulder):
emergency (police) vehicles and/or for broken-down vehicles.
3.4.4 traffic flow (british) or volume (american): the number of vehicles passing a specific point in a stated time
in stated direction(s). In tunnel design, peak hour traffic, vehicles per hour per lane, will be used.
3.4.5 speed limit: the maximum legally allowed speed.
3.4.6 design speed : a speed adopted for a particular stated purpose in designing a road.
3.4.7 reaction time : the minimum time interval between the occurrence of an event demanding immediate action
by the driver and his response. The reaction time includes th time needed for perception, taking a decision and
the stopping distance SD is the distance needed to bring a vehicle, driving at design
3.4.8 stopping distance SD:
speed, to a complete standstill. The SD is usually defined in national legislation or regulation. The concept "Safe
stopping distance" is not used in this standard.

1) The terms indicated conform to the "Vocabulary of traffic engineering terms", published by Traffic
Engineering and Control, London, 1960.

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3.4.9 mixed traffic: traffic that consists of motor vehicles, cyclists, pedestrians etc.
3.4.10 motor traffic (motorized traffic): traffic that consists of motorized vehicles only. It depends on national
legislation which vehicle types are included in this classification. In some countries it only includes vehicles which
are capable of maintaining a minimum speed. In others, mopeds are not considered as motorized traffic.
Remark concerning traffic flow : if the actual value is not known, peak hour traffic can be derived as follows. Average daily traffic
(ADT, vehicles per day) is the most used concept in traffic planning and it is always known. Peak hour traffic (vehicles per hour) is on
rural areas 10% and in urban areas 12% of ADT. On undivided roads, number of vehicles per hour per lane can be calculated by
dividing peak hour value by the total number of lanes. If the actual directional distribution is not known on dual carriageway roads,
assumption 1:2 can be made. Then the higher flow will be divided by the number of lanes of this carriageway.
4 General aspects of tunnel lighting
4.1 Tunnel conditions
Road and traffic conditions in tunnels may differ considerably from those that prevail on the open road. The design
of tunnel lighting installations should take these different conditions into account, in particular as regards the traffic
safety aspects.
It is desirable to measure tunnel lighting installations after completion to ensure that the design requirements have
been met. Advice on measurement is given in section 9.
4.1.1 Stopping Distance
Important parameters for the design of tunnel lighting installations include the speed, volume and composition of
traffic flow entering, and passing through.
There is a strong, but non-linear relationship between the traffic flow and the accident risk: higher volumes show
a higher accident risk (with the exception of very low or very high traffic volumes). The extra risk can be
counteracted, at least in part, by increasing the light level. This relationship is established for many types of open
roads, and it is assumed that it also holds for tunnels.
One of the most important factor is speed. In practice, road and tunnel designs are such that speed and flow usually
are interrelated, as a high design speed is selected for roads for which a high flow is expected. High speeds require
better visibility and therefore generally a higher luminance level.
The stopping distance SD that often has to be evaluated for the correct design of the lighting is the sum of two
stretches of road:
• the x distance covered during the reaction time
• the x distance covered during the braking time
If u is the travelling speed, constant at the beginning of the stopping action,
x = u⋅t (1)
o o
where t is the reaction time.
The x distance can be calculated comparing the impulse for a dt time with the momentum

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Figure 1: forces acting on a vehicle with different slopes.
⋅ ⋅ ⋅ b6 ⋅ ⋅b⋅ ⋅
- (f m g cos m g sin ) dt = m du (2)
f  =  friction coefficient tire-pavement
m = mass of the vehicle
g  = gravity acceleration
the + sign must be considered for ascending slope; the – sign for descending slope.
=bThe time dt can be expressed as dx/u. Introducing the slope s  tan the (2) becomes:
- cosß⋅g⋅(f6s)dx/u = du or
dx du
cosb⋅ g ⋅ f s
Being cosß always close to the unit, it can be neglected.
Integrating the left-hand member between the distance 0 and x, the right-hand member must be integrated between
the speed u and the speed 0. So:
x 0
dx =-du
∫ ∫
g ⋅()–f s
0 u
The integration of the right-hand member is impossible because the friction coefficient f is an unknown function of
the speed and other parameters depending on the speed, such as the atmospheric conditions, the tires condition
and so on.
But assuming f as a constant versus u the (3) gives:
2 ⋅ g ⋅()–f s


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With this hypothesis the formula (4) can be used to determine x if the friction coefficient is assessed by practical
tests and reported in a graph as a function of the speed.
Fig 2: typical diagrams of the friction coefficient as a function of the speed for dry and wet pavement.
Summing the reaction distance (1) and the braking distance (4) the general formula of the stopping distance is
SD = u ⋅ t +
2⋅ g ⋅()–f s
In all the hereabove formulae’s (except in the figure 2 where u is expressed in km/h), u is expressed in m/s, x in m,
t in s and g is equal to 9,81 m.s-2
Without any particular value, t can be assumed equal to 1 sec and f taken from the curve of fig. 2 for wet pavement
as a function of the design speed.
4.1.2 Tunnel lighting requirements
The lighting of a tunnel entrance should be adequate:
– to avoid the 'black hole effect' when a driver is unable to see into the tunnel;
– to reduce the likelihood of a collision with another vehicle (or bicycle or pedestrian);
– to enable a driver to react and stop within the SD if an unexpected hazard appears.

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4.1.3 Traffic composition
The traffic composition is relevant for the tunnel lighting in several aspects:
– the percentage of trucks;
– the presence/absence of pedal bicycles and/or mopeds;
– the presence/absence of pedestrians (non emergencyconditions);
– the presence/absence of authorization to allow the transit of hazardous material.
The lighting has to be adapted to these circumstances. Higher levels or better quality lighting for the walls or the
road are necessary for the visual task when the conditions are more difficult or more hazardous.
4.1.4 Road and tunnel conditions
Driving comfort is an important aspect of the quality of the lighting installations of road traffic tunnels. Tunnels,
constructed to overcome traffic obstructions, should not become a traffic obstruction by themselves. The design should
be such that the traffic flow in and through the tunnel must be just as fluid as on the open road. As a result of feelings
of anxiety, drivers are likely to slow down near the tunnel entrance. Sudden drops in speed reduce the traffic capacity
and easily might lead to traffic jams and even to accidents. So, a good lighting that helps to overcome any feeling of
anxiety is not only a matter of driving comfort but also a matter of road capacity and of traffic safety.
This may be explained as follows. Driving a car safely is mainly a matter of attention. On long stretches of motorway,
attention may waver and the level of arousal is low. Drivers are not well prepared to cope with emergencies should they
occur unexpectedly. Near tunnels, the attention must be higher to cope with additional hazard factors. Tunnels, being
low and narrow, might cause concern or even fear, but also will lead to an increase in arousal. The fear and the arousal
are likely to cancel out each other to a large extent, so that the more dangerous tunnel entrance need not to lead to
more accidents. However, what happens to the driving comfort is another matter.
The object of installing lighting in a road tunnel is to enable the traffic to pass through with the same degree of
safety and comfort, as is customary on the open road, and with an acceptable speed. The difficulty of the driving
task when approaching and passing through a tunnel is mainly influenced by the speed, the volume (flow) and the
composition of the traffic and by the layout of the road and the tunnel and their immediate surroundings. To enable
a road user to drive safely when a tunnel is on his route, it is pertinent to give him adequate and relevant
information, which allows the driver to situate himself in space and time, to foresee a "model" of his future position
and to adapt his behaviour to this anticipated "model".
When making the lighting design for a tunnel, the following aspects should be taken into account:
a) Altered perception
The spatial perception is confined and cut off from any familiar reference marks. The walls may generate a "wall
shyness effect" which tends to make drivers keep further away. Drivers' visual performance may be considerably
lower, especially regarding visual acuity, the perception of contrast and distances, peripheral vision and the
discrimination of colours. Time perception may change: the perceived duration seems to be about twice as long as
the actual time span. And finally, some drivers can be affected by sensations such as claustrophobia.
b) Overall perception

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1. Before entering a tunnel
– the layout should clearly show that one is approaching a tunnel - this should be supported by relevant signs;
– portals should be constructed with dark materials in order to reduce the access zone luminance;
– there should be a black asphalt surface for the road up to the portal.
2. Entering the tunnel
– East-West orientations may cause more problems than North-South orientations;
– avoid light coloured surfaces in the immediate surround of the portal such as buildings, walls, etc.;
– adopt trees or other screens to avoid direct glare from the sun.
3. Inside the tunnel
– if discontinuities, ramps and intersections in the geometric design, it is advised to treat them specifically by
an ad hoc lighting system;
– adopt a light coloured road surface that should be near diffuse for symmetric lighting and more specular for
counterbeam lighting;
– adopt and maintain good guiding facilities (road markings, delineators etc.) along the road;
– adopt separate sign lighting when the tunnel is lit by monochromatic light-sources.
4. At the exit
– adopt, when a glaring situation may be expected outside the exit, civil engineering works or planting that will
screen off the direct sunlight.

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4.2 Distinction between long and short tunnels
The lighting requirements for long and short tunnels differ according to the degree to which the approaching motorist
can see through the tunnel as seen from a point at a distance equal to the stopping distance in front of the tunnel
portal. The ability to see through the tunnel depends primarily on the length of the tunnel but also on other design
parameters (width, height, horizontal and/or vertical curvatures, etc).
Short tunnels normally occur when a traffic road passes under another road or railway or are covered over for a
short distance in urban situations. Tunnels shorter than 25m do not need daytime lighting. Tunnels longer than
200m always need some kind of artificial daytime lighting to avoid adaptation problems for road users. For tunnels
of length between 25m and 200m, a method to determine if daytime lighting is needed is given in Annex A5. Another
method produced by the CETU may be found in the following reference (Cetu Dossier pilote des tunnels; Novembre
2000; Centre d‘Etude des tunnels ; Bron, France).
The need for artificial lighting during day-time is determined by the degree in which other road users or objects are
visible for a driver in front of the entrance at stopping distance against the scene behind the exit which is lit by the
When the exit portal is a large part of the scene visible through the entrance other road users and objects can easily
been seen as dark against the lighter scene behind the exit portal. At the other hand artificial lighting is needed
when the exit is in a relative large dark frame, in which objects can be hidden. This can happen when the short
tunnel is relatively "long", or when the short tunnel is curved in such a way that only a part of the exit can be seen
or when the exit cannot be seen at all.
So the critical factor is whether approaching drivers when their distance from the entrance portal is equal to the
stopping distance can see vehicles, other road users or obstacles.
For determining the need of artificial daytime lighting the "Look Through" is used.
The "Look Through" is defined a

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