Transportation Engineering – II
Dr. Rajat Rastogi

Department of Civil Engineering
Indian Institute of Technology – Roorkee
Lecture – 39
Visual Aids – Markings
Dear students, we are now reaching towards the end of our lecture series and at this
junction, we will be discussing about some of the remaining things which are important
as far as operation of aircraft on any airports are concerned. In that sense we will be
looking at the various visual aids and these two lectures, that is this and the coming
lecture, are devoted to this aspect only. In today’s lecture, we will be looking at the visual
aids related to markings which are provided on any of the components of the airport. So,
in that sense, this lecture is being outlined in the following way.
(Refer Slide Time: 1:10)
We will be looking at what are the visual aids and then, what are the markings which are
provided for different components, specifically for runways and taxiways. In this
connection we will be starting with visual aids.

(Refer Slide Time: 1:33)
The visual aids are basically the things like they are the landmarks which are required, so
as to provide an aid to the pilots. So, for performing the landing or take-off operations
and the major objective here is to maintain the safety of that operation. So, the various

markings, various aids which are going to be provided in any of the form, they try to
ensure that whatever operation is going on, the pilots and related crews or the related
controlling persons are in a position to visualize that this operation goes on smoothly and
efficiently, at the same time maintaining the safety aspects of that operation.
These visual aids, whatever the way they are provided, are required both in good weather
condition as well as during the bad weather condition or not only during the days, but
also during the nights. So, it means the visual aids which are provided on any of the
airport should have a universal applicability and it should not be dependent on any of the
aspects which may create its effect on the operation of aircrafts on that airport. The
runways or the conventional aircraft appears as long and narrow strip with straight sides
and free of obstacles. This is how it looks like. If you look at any of the runway strips or
if you are looking at any of such operations, then what we find is that those runway strips
or the aircrafts which are using those runway strips, they look like long and narrow strips
with certain straights sides which are defined and we will be, we will be finding that they

have been marked in a certain way, so that we can clearly distinguish between the strips
being provided or the surrounding areas and then in all the cases, these are going to be
free of obstacles.
(Refer Slide Time: 3:37)
The perspective view of the runways along with the landmarks like horizon, runway

edges, runway threshold and centreline of the runway are the most important elements for
pilot to see, because if any pilot is making a sort of an operation like there is a landing
operation which is going on, then in that case it becomes very important for the pilot to
understand that or tend to locate that where is the horizon, where the runway edges are,
what is, where is the runway threshold which needs to be crossed at a certain height with
the specified speed and then, where is the centreline of the runway along which the
aircraft needs to be aligned, so that the safety is ensured while it is taking a landing.
Similarly is the case for take-off and we have seen when we have designed the length of
the runways strip, that during the take-off also at end of the runway strip or certain
distance away from the runway strip, there are specific heights which needs to be
maintained. So, in that sense, if we are looking at these considerations, then it becomes
very important for the pilot to understand and to find out all such components, all such

type of say markings or lightings or any other type of aid which has been provided, so
that the pilot can make a perspective view of overall runways strip which they are going
to utilize for landing or take-off operation and within that perspective view, the whole of
the operation will be taken care of.
So, in this sense, if we have to enhance the visual information and the so as to enhance
that, certain specific type of paints needs to be used and these landmarks are painted in
standard patterns, which are going to be uniform throughout. They are generally defined

by the bigger guiding agencies which provide the guidelines regarding these visual aids
and when we are using these in the standard pattern across all the airports or across the
countries, then the pilots do not have any problem in understanding those patterns and the
significance of those patterns and on the basis of those significance of the patterns, they
can do the landing or the take-off and therefore, there are certain specific colours which
needs to be used or if it is lighting system, then again in that case also the different
coloured lights needs to be used, so that the visual information reaches the pilot in as
clear way as possible, so as to make a safe landing or take-off.
(Refer Slide Time: 6:38)
In that sense the visual aids are going to perform certain purposes and they are that there
is a need to avoid accidents during landing of the aircraft. That is the one objective of
providing the visual aids. Then, the visual aids help in conveying the pilot the ground to
air information. This is the way by which the overall information which is available on
the ground is conveyed to the pilots, so that they can arrange themselves, they can orient
themselves with respect to that information during the operations. They direct the pilot
during landing.
This is another important aspect, because as we have seen that there are certain distances
and there are certain points like there is a touch down point on the runways strips,
similarly there is a lift off point on the runways strip. These points are all located on the
strips in certain form and the pilot understands that and accordingly they orient
themselves, so that they can use that particular area which is being specified for that type
of operation and it also enables to pilot to locate and identify a particular feature.
That is what I was just telling that if they have to locate the touch off point, then they will
be able to understand that where the touch off point will be coming and so, they can bring
their aircraft with that altitude and a speed, so that at a time of touching there is no safety

hazard and it grants safety to personnel and properties and that is how it is going to
happen. So, who so ever is traveling in the aircraft, the crew, the passengers, similarly the
properties which are associated with it, like the aircraft itself, the cargo which is being
transported or the things which have been provided on the sides of the runway strips,
everything needs to be maintained as safe as possible and this is the way by which we can
do it.
Another important thing is that it also maintains an orderly flow of aircrafts. This is
another important aspect, because if these type of markings are not being provided, say
there is a runway strip which is utilized for unidirectional type of operations that is from
one end there is a take-off and from other end there is a landing, then in that case, the
aircrafts cannot do the opposite operation on these particular ends.

So, that is the thing which is there that is there is an orderly flow of aircrafts. From the
landing side there will be only landings and from the take-off side, there will be only
take-off on the runway strip as an example and it also helps during take-off as well as
during taxiing, because the aircraft which has already landed on the runway strip can
understand the other markings, other visual aids being provided by which it can move
towards the exit taxiways or the taxilanes or to the taxiways by which it will be going
towards the storage area or the aircraft stands, where they will be taxiing or where they
will be holding or they will be going towards the terminal aprons. Everything is being

defined in terms of the visual aids and following those visual aids, the aircraft can reach
their ultimate destinations and these visual aids, as we have been discussing, are available
in different forms.
(Refer Slide Time: 10:23)
They are available in the form of airport markings or airport lightings or signage. So,
these are the three ways in which we can get the different visual aids. Airport markings,
or airport lightings or signage, they are all related to various type of operations. They are
related to the different components which are provided on any of the airport and that is
why at each and every point, we will be getting the information and we will be looking at
all these three types of information during these two lectures. So, in this lecture we are

going to concentrate on the markings. In the next lecture, we will be discussing about
lightings and the signages. So, in that sense, once we have taken an idea and the
objectives of providing the various visual aids, we start looking and discussing about the
airport markings.
The airport markings are the things which are basically provided on any of the
component and they are being provided in the form of the strips or in the form of the
patches or in the form of the solid lines or in the form of the hollow lines or the cart lines
and there are different ways in which these are done. They are perpendicular, they are
angled and they are used in all the components, so as to define those things. In that sense,

if we look at the various types of the markings which can be there, they can be grouped
on the basis of the component where they are going to be provided.
(Refer Slide Time: 12:13)
In that way these are provided in the following groups like apron markings, the landing
direction indicators, the runway markings, shoulder markings, taxiway markings, wind
direction indicator. So, once we have all these type of markings, then we will be starting
now with the first one that is apron marking.

(Refer Slide Time: 12:31)
Apron marking provides guidelines which are marked on the apron to help the pilots in
maneuvering the most critical aircrafts. So, most critical aircrafts means here is that
whatever is the biggest type of the aircraft which is going to use the airport, then the
operation of that one, the maneuvering of that one in terms of its turning, in terms of its
movement, everything is guided by using the apron markings and generally, these are
related to the path to be traversed during parking in or out operation near terminal
location of nose, etc., means as we are, as we have seen previously when we have
discussed about the terminal aprons and the terminal aprons are being utilized by the
aircrafts, so as to stand on that one very near to the terminal building, where they need to
be loaded and unloaded. So, they have also looked at the various orientations or the type
of parkings in which that can be done.

Now, how an aircraft is going to be parked or how an aircraft is going to be taken out or
taken in or how it is going to take a turn, at what particular location it has to stop and
then, there can be a loading and unloading, everything is defined by using some
markings, which are provided on the pavement which is located on which the aircraft is
standing and that pavement is nothing but, it is the apron way. This is, this type of thing
we have observed in one of our lectures and we will be looking at the same in this lecture

too. In this case, most of such things are provided by using yellow colour. So, yellow
colour painted things are provided on the pavement surface and on the basis of that it is
being defined.
Another thing is that, when we are using this colour or in that colour should be fuel
resistant because there are all chances that during the filling of the aircrafts or during
certain other maneuvers, the fuel may spill and that may create a problem to such
markings. So, that is one important specification of the paint which is used as a marking
on the airports. That is they should be fuel resistant.
(Refer Slide Time: 15:07)
This is one diagram which I was talking about and which we have looked at previously
too and this is one of the type of the marking which will be found just on an apron. This
is basically the pavement and the aircraft is going to come and stand on this pavement
and what is the orientation which this aircraft is going to take with respect to the building

line that is already being defined that it is an angled condition, wherein this is coming
with nose in condition. This is angled nose in condition by which it is coming, because
this is some angle theta with respect to this building line or this building line, because this
is L shape building line being provided and in that sense, if the aircraft is coming from
this side, then it will be taking a turn and will stand in this form.
So, if the turn is going on, then obviously it is to be defined in the form of the path this
wing will be taking and that is how it is being defined by this line. That is this is the path
which will be taken by the wing. Similarly, when it will be going out after the loading,
then this will be taking a turn in this way. So, this is how it is going to take turn with
respect to this point of turning which is found out on the basis of the main gear line and
the steering gear line and the point of intersection of these two is defining this turning
point.
So, when we are looking at this type of maneuvers, then this aircraft location is being
shown as here will be depicted on the pavement surface in yellow colour and then, this
type of path of the nose wheel or the inbound condition or outbound condition. So, this is
the path of the nose wheel. First of all, the aircraft will come in this form and then, it will
start taking a turn. So, this is how it will be taking at turn and will be come in this
condition. So, once it has done this, so this is how the nose wheel will be moving, it will
be in, the initial condition will be here and then, as it will start taking a turn, it will be
taking a path like this. So, this is how it will happen and then, once it is being loaded, it is
to be taken out.
Now, this will be moving along this particular path. So, we have the out bound turning
radius and we have the inbound turning radius and the minimum radius with which it will
be working that is this value. So, likewise, everything is defined for this sort of an
operation and some clearance with respect to the building line is also being provided, so

that there is no damage to the wings of the aircraft while it is taking a turn and moving
away from the building.

(Refer Slide Time: 18:02)
So, another type of indicator is landing direction indicator. This landing direction
indicator is a helpful aid to the pilot, at the time when they are coming to the airport and
looking for a runway strip and the direction from which they can land on that runway
strip. So, that defines the pilot and the pilot will be able to visualize, pilot will be able to
see that particular indicator and on the basis of that indicator, he or she will be orienting
the aircraft, so that they can land in that direction. So, this is what it indicates, the landing
direction and it is provided in the form of may be an arrow or a tee is placed at the center
of a segmented circle. These are the two ways in which it can be provided.
So, if it is not in the form of an arrow, then there can be a segmented circle that is a circle
being provided with cut off lines and then, in the center of that segmented circle, there
can be a tee shape being located. It is painted orange or is painted white in colour. So,
these are the two colours which can be used for this landing direction indicator. It is
lighted for viewing during night time. So, all these indicators which are provided, they
are provided with the lighting systems, so that the pilot can view, can locate these landing
direction indicators during the night. They are fixed and they are at a distinct place.

(Refer Slide Time: 19:48)
This is the T shape landing direction indicator, which needs to be provided in some of the
cases. In that case, there will be an encircling circle like this and this one and that circle
will be cut off at uniform distances. The size of this T is being defined here for a specific
type of runway strip and depending on the size of the runway strip there can be some
modifications, but in general it is like 4 meter wide in this way. 0.4 meter wide is this
strip. Similarly, this strip is also 0.4 meter wide and this is again is 4 meters. So, this is
the type of landing direction indicator.

(Refer Slide Time: 20:32)
Another indicator which is provided on any of the airport is the wind direction indicator,
which helps the pilot to understand, to find out in which particular direction the wind is
blowing and this is important as far as to be understood by the pilot that what type of
food needs to be provided at the time of taking off or at the time of landing. If the wind is

coming in the cross wind component form, then what will happen or of it is coming in a
head wind or a tail wind component form, then what is going to happen. So, that will
become very clear as shown as the pilot looks at this wind direction indicator and it is
generally provided in the form of wind cone on all the airports.
Generally, this is placed within a segmented circle together with the landing direction
indicator. So, means the pilot need not to look to two different directions, so as to locate
both the information. Both the information will be available to the pilot at the same
location and it is in the form of segmented circle on which a T is being placed and then,
along with that T, there is a …… has been provided on which a wind cone will be there,
which moves in certain direction indicating the direction in which the wind is blowing.
Then, it should be placed at a conspicuous place away from the building, so that it is not
affected by the eddies, because if there is heavy wind blowing, then if it is very near to

the terminal building, then the eddies will be formed and in that case, it will not be useful
to the pilot to understand the behavior of the wind. The panels forming segmented circles
are gable-roof shaped with a pitch of at least 1:1. That is the specification for the
segmented circle which is provided. So, it is a gable shaped segmented circle.
(Refer Slide Time: 22:52)
Panels are painted white in colour and the length of wind direction indicator should not
be less than 3.6 meters and its diameter at the larger end should not be less than 90

centimeters. So, this is the specification related to wind direction indicator. The length is
being defined and the diameter is being defined at the larger end. It should be visible
from a height of 30 meters. So, this is height which is generally required at some
kilometers away from the runway strip that is the end of the runway strip or the reference
point being taken with respect to the airport or the airport runway reference point. It is
painted with bands of colours like white and black, red and white, orange and white, etc.
This is the way it is provided.

(Refer Slide Time: 23:52)
This diagram tries to show the same thing. This is one segmented circle, has been shown
here. The inside diameter of this segmented circle is 30 meters. Within this segmented
circle we are providing the landing direction indicator as being shown here. This is a T
which is being located, so this is trying to tell the landing direction and then, at the side of
this one, this wind cone is being provided which is showing that the wind is flowing in
this direction here and this will be in the form of, like this. There is a hole and top of this
hole there will be a this conical form of surfaces being provided with 0.9 meter of the
diameter at this side and 3.6 meter length of the cone. So, that is the minimum
specification related to this one.
At the same time, these segments which are provided or the panels which are provided,
the sizes of these panels are also being specified. Here, these panels are having a width of

0.5 meters to 2.4 meters and the length is from 1.8 meters to 3.6 six meters and they are
provided with spacing between the panels and the value is again almost the same way as
being provided with respect to the length of these panels. So, that is how they are
uniformly placed in this way.

(Refer Slide Time: 25:25)
Now, once we have looked at these two types of specific indicators which help during the
landing operation then, now we are going to look at some of the markings which are
provided on any runway strip which helps the pilot, may be during landing as well as
during the take-off. These are provided with different purposes and these purposes are
like they have to be provided for the centreline, they need to be provided for the edge of
the runway strips or there is a numbering for each and every runway strip, which we have
seen in the previous some of the figures, which we have discussed during some lectures,
where numbers were shown like 27, 9 or so on. So, that is the numbering of the runway
strip that needs to be provided.
Then, as we have been discussing about the landing condition, so touch down zone or it is
also known as the landing zone, so for that reason where this landing zone or touch down
zone is that marking needs to be provided. Then, there is a threshold marking, which
defines the specified height by which the aircraft should cross it, so that they can reach
the touch down point in very safer condition. Then, in case there a more of runway strips,

then the markings relate to those two or more parallel runway strips.

(Refer Slide Time: 26:59)
Now, we look at the very first type of the runway marking which is provided and this is
runway centreline marking. This runway centreline marking is provided along the entire
length of the runway strip. Now, this is one thing, because from very starting to the end
this has to be there. Second thing is that it is not solid continuous line, whereas it is a
broken strip. So, as we have seen in the case of segmented circle, here it will be straight
line profile, but then again there will be certain length for which the marking will be
provided and then, there will be a gap between the two centreline markings in this form.
The length of the strip should be equal to the length of the gap or 30 meter, whichever is
greater. So, that is the way this centreline strip is provided. Length of the strip plus a gap
shall not be less than 50 meter or more than 75 meter. So, in this sense if we look with
respect to the previous one, where we are talking about that it should be equal to the
length of the gap or 30 meter whichever is greater and if we assume this 30 meter is the
greater value, then in that sense the gap is going to be 20 meters if we take the value of 50
meters or otherwise, if it is going to be more in the case of the length of the strip is taken
more than 30 meters, then we can have again in this case something like 30 meters to 40
meters gap. So, depending on what length of this strip is being taken and with respect to
that we can find out the gap using this specification.

The width of the strip shall not be less than 90 centimeter on precision approach runway
strips and 30 centimeter to 45 centimeter on non-precision approach runway strip. So,
these has been defined on the basis of the type of the runway strips being provided and
what type of approach is being provided for that runway strip, whether it is a precision
approach means it is instrumental condition, where everything is being defined by the
instruments, the altitudes, the speeds, the grades, everything, whereas in the other case, if
it is a non-precision condition where such type of devices are not being used and on using
the markings and the standards known to the pilot the operations are carried.
Another type of runway marking is runway touched down marking. We will be looking at
all these markings like the first one which we have just discussed that is centreline
marking and one of the diagrams where combination of these markings has been shown.
(Refer Slide Time: 30:19)
Now, in the case of this touch down marking is provided in the touch down zone and it
consists of pair of rectangular markings which are placed symmetrically about the
runway centreline. What happens is that the aircraft is coming along the centreline on a
runway strip and it is coming slowly and slowly down that is there is a downward grid
with which it is coming. So, these centreline marking, these touch down markings,

basically define the way the aircraft has to move and by what particular point afterwards
only the touch down can be done. So, therefore there will be a zone in which this touch
down will be made.
These markings which are provided on the both of either of the side of any centreline
marking of the runway strip, they are 1.8 meters wide and they are spaced at 1.5 meter
clear distance that is from the end of one marking to the start of the other marking, the
distance is 1.5 meters. The length of these markings are 22.5 meters. So, they are 22.5 by
1.8 with the gap of 1.5 meters.
(Refer Slide Time: 31:46)
Here, in this diagram we are going to look at the combination of the runways, centreline
marking and touch down marking. Here, in this diagram, we can clearly see the centreline
marking. This one is the centreline marking, has been shown here. This is 90 centimeter
wide strip and then, there is a touch down marking which is being shown in the form of 4
strips on either of the side at the start. Then, it reduces to 3 on either side, then it reduces
to 2 on either side and then, it becomes 1on either side. The length of this remain 22.5
meters, the width remain 1.8 meter wide and the gap between the markings is 1.5 meter,
clear.

So, starting from these 4 lines which are provided to the single line, which is being
located up to this particular distance, as we are providing them, that is the runway touch
down zone. So, the aircraft will be coming and will be touching at this location and these
strips are provided depending on the requirement; this number will be changing. There
will be four four strips and then, the three three strips and so on.
(Refer Slide Time: 32:57)
Now, there is another diagram which is being shown here. This again tries to show the
different type of the markings which can be there. Here, we are showing the threshold
markings at the bottom which are like the ….. crossing markings and this defines the
threshold of the runway strip away from the end of the runway strip. So, it is at some
distance from the end of the runway strip. This is the basic pattern which is provided and
here this is the aiming point marking which is located here, this bigger strip which is
being provided at this location or at this location.
This is usually at a distance of 400 meters from the end of the runway strip and from this
direction, there is going to be a landing. So, this is runway number markings which is
20L means, L for the left and 20 defines the angle at which this runway strip is being
provided with respect to the overall angles of space that is 360 degrees. So, it is 200

degrees is the angle in this case and then, this is the centreline being shown in this basic
diagram and along with that one, we have the touchdown zone markings, which has been
as a single strip on both the sides and T is going up to this distance. So, this becomes the
touch down zone.
Here, in this case as we have seen in the previous diagram there are some more lines, like
there is a three line and three lines likewise and then there are two lines and so on and
then, there is a single line and finally, we have this much distance which is defined as the
touch down zone marking. So, this is with the direction coding and this is with the basic
type of patterns. So, direction coding means this will be going in this direction for the
landing.
(Refer Slide Time: 34:59)
Now, we look at another runway marking that is the edge stripe marking, which defines
the ends of the runway strips on the two sides of the centreline markings. So, this runway
edge strip consists basically of two strips. One is placed along each edge of the runway
and it is continuous in nature and in this case, the width of the runway if it is greater than
60 meters, then the strip is located 30 meters from the runway centreline. So, that is the

way it is provided. Generally, these are 90 centimeter wide. This is the most general
width which is used for the strips.
(Refer Slide Time: 35:42)
There is another type of marking which we have seen in the previous diagram, which is
the runway threshold marking. This runway threshold marking consists of a pattern of
longitudinal strips of uniform dimensions. That is they are of same length and same width
and they are placed symmetrically about the centreline of a runway strip and they extend
laterally within 3 meter of the edge of the runway strip, means from the edge of the
runways strip it goes up to 3 meters from the sides. So, that is how they are located. So,
on the basis of this particular specification, whatever are the number of strips needs to be
provided for threshold marking will be computed based on the width of each marking as
well as the clear gap between those markings.

(Refer Slide Time: 36:40)

These are generally 1.8 meters or 3.6 meters wide with spacing of 1.8 meters or 0.90
meters between them and are 45 meter in length. So, these are the specifications for
providing these markings. Sometimes, it is desirable to displace the runway threshold and
it is usually adopted to clear obstructions in the flight path, because if there are certain
obstructions which comes on the flight path, then if by just displacing the threshold,
means taking the aircraft to a certain further distance towards the airport, may clear those
obstructions and therefore, it becomes safer movement.
We look at the runway edge stripe and the threshold markings in this diagram.

(Refer Slide Time: 37:27)
What we can see is that, here this was the centreline marking which was, which we have
discussed previously. Then, here with respect to this centreline marking, at this position
the centreline marking is there, this is the alignment. With respect to this one,
symmetrically we are providing threshold markings, on this side as well as on this side.
So, they are starting at distance of 6 meters from the end of the runway strip. So, this is
what is the normal basic way of providing the threshold markings. These are 45 meters in
length and then, as we have seen the width is variable along with the gap being provided.
Here, another type of marking which is shown is the edge stripe marking which as I have
told, is a continuous strip, 90 centimeter wide and is located at the edge from this side as
well as from this side. Therefore, there is a pair of this marking and these threshold

markings can come within 3 meters of this edge strip marking.

(Refer Slide Time: 38:29)
This is another diagram which tries to show the displaced threshold. Here, the arrows are
showing the direction in which the landing will be taking place. So, this is another type of
landing direction indicator which is used on any runway strip and then, in case of the
displaced threshold a line is to be provided like this which is 3 meters minimum of width
and moves across the runway strip. So, it defines that this is the end of the runway strip in
this sense, because we cannot use this end of the runway strip due to the obstructions and
then use, as the same way as we have done with respect to the end of the runway strip,
from a distance of 6 meters the threshold markings will be provided and here the arrows
which are being located they are 36 meters in length with the clear gaping of 24 meters
between the two arrows stripes.

(Refer Slide Time: 39:31)

Now, there is another diagram for this runway displaced threshold marking. We can see
different type of ways of doing the same thing. This is the one which we have already
seen, where this is the, this defines now the end of the runway strip and with respect to
this we have the threshold markings and this is the centreline marking and these are the
arrows being provided this way. Different dimensions have been shown here. Another
way of doing the same is in this form and then, there is a temporary displacement is there.
That is why this is thinner line and the arrows are showing that you are moving in this
direction. So, this is temporarily displaced threshold condition. This may be a temporary
or a permanent displaced threshold condition.

(Refer Slide Time: 40:21)
Then, another type of marking is the runway numbering. In this case, the end of each
runway is marked with a number which indicates the magnetic azimuth that is what we
have seen in the previous one diagram that 20L was written. So, 20 is trying to define the
magnetic azimuth. That is the angle measured in clockwise direction from the North of
the runway in the direction of landing. So, if we move with respect to the North direction
in this form of a clockwise direction, then at an angle of 200 degrees, we are trying to
show this runway strip and for that it will be written as 20L.
Like there is an example, there is an East end of East-West runway would be marked as
27 for 270 degrees and the West end will be marked as 9 for 90 degrees. The magnetic

azimuth is marked to the nearest 10 degrees value.

(Refer Slide Time: 41:27)
Here, in this diagram, we are trying to show again, there are number of runways strips
which are intersecting with each other and in that sense, here this is 13, this is 13. 13 is
for this direction. So, this is 130 degree, whereas when we are looking at 31, so this is for
this direction, it means we are going at an angle of 310 degrees with respect to the North
direction. Similarly, like this is 27, because we are going into 270 degree angle condition
or this is 9, because we are going towards the 90 degree angle condition. So, it is all
respect to North condition and this is another example which we have just discussed with
respect to East and West and that is having a value of 9 and 27. So, these are the runway
numbering stripes.

(Refer Slide Time: 42:15)
Then, two or more parallel runways if are provided on any of the airport, then in that

case, there is a specific way in which this is to be defined to the pilot. As we have seen in
the previous one of the cases that it was written 20L, it means that there are two runway
strips and in that case, one will be a left runway strip, another will be a right runway strip.
So, if there are more than one runway, in that case, we will be using some of the letters,
so as to define what number of runway stripes are being provided and here like for two
parallel runways we will be using L and R, for three parallel runways we use left and
right with central. If there are four parallel runways, then there is left and right on this
side and left and right on the other side. When it is five parallel runway conditions, then
we have L C R and L R, like it depends in which particular way the parallel runways have
been provided.
So, we have one set which has L C R condition and then there is another parallel set
being provided which is defined by L and R condition. So, this gives the information to
the pilot that there is another runway strip on the other side and the pilot has to be careful
with respect to the operations which are going on, on the other runway strip.

(Refer Slide Time: 43:44)
These are the things which have been shown here. There is a number of different ways by
which this marking can be shown, like it is 20 being defined here, it is 9 meters long in
this form. So, this is 9 meters long. Another way is that there is a 20L condition. So, 20L
can be written as 20 with L as the bottom or it may be 20 and L in continuation. That is

the two ways by which it can be done and the other one, third way is that we can use this
20 within the threshold markings. So, this is the way this within threshold marking it is
being done. So, there are different ways by which the runway markings can be provided.

(Refer Slide Time: 44:23)
Now, in this diagram, we can look at the various types of the markings which we have
discussed so far, like these are the threshold markings being provided. Then, there are the
centreline markings being provided like this. Then, there are the touch down zone parking
being shown in this form, in this form or this form. This is the fixed distance marker or
the airline pointer. These are provided in wave form. The distance is also being shown.
Then, there will be an edge strip marking to be located on this side which is not being
shown in this diagram.

(Refer Slide Time: 45:03)
Apart from these runway markings, then another set of markings are shoulder markings.

Here, the markings are in the form of yellow stripes, which are again 90 centimeter wide
and they are provided at a distance of 30 meters from each other. But at the point where
there is a turning, these are provided at a distance of 15 meters. The marking extends up
to a maximum of 1.5 meter from the outer edge of the shoulder. So, whatever is the edge
of the shoulder, from that point it goes up to a value of 1.5 meters.
Runway shoulders are marked with diagonal lines that is at an angle of 45 degrees,
whereas the taxiway and holding apron shoulders are marked with stripes which are
perpendicular to the direction of travel of aircraft. So, that is how a pilot can understand
that they are moving away from the runway and they are coming on the taxiway or
holding apron. So, as soon as the markings become straight or perpendicular to the edge,
it means the runway is over and they are moving on taxiway or holding apron.

(Refer Slide Time: 46:14)
The blast pad at the runway end is marked with chevron or V-shaped lines. So, we can

have the V-shaped lines, which defines that this is the blast pad or from that particular
direction the take-off will be taking up on that runway stripe.
(Refer Slide Time: 46:29)
This is one diagram which tries to show the things like this is a runway strip. So, with
respect to this runway strip, on the two edges the markings have been provided at an

angle of 45 degrees and they are located at a distance of 30 meters, but when it comes
towards this turning area, then it will be located at a distance of 15 meters. Then, here in
this location, a blast pad is being provided and this is provided with V shaped chevron
that is the way it is being located, it is being provided and the aircraft will be taking a
take-off in this form. Then, here what we see is that, in this one still they are the angle
conditions. That is the part of the runway and as soon as it comes to the holding apron,
then they become perpendicular to the edge. So, we can look at these perpendicular strips
being provided and at the maximum, they can go up to a distance of this 1.5 meters, like
this one, like this and here this is the point of turn and in between these point of turns it is
located at a distance of 15 meters. So, this is how they are being located here. From the
edge it is 1.5 meters on this side.
(Refer Slide Time: 47:52)
Now, centreline of taxiway consists of 15 centimeter. This is another type of marking,
which is 15 centimeter wide and it is provided in the form of continuous stripe of yellow

colour. So, along with this one, there will be again the different other markings which
will be there on a taxiway. One of the types of the marking we have already seen in the
previous diagram, where we have looked at the edge markings provided on the taxiway
also. Now, the intersection with runway end, the centreline of the taxiway is terminated at

the edge of the runway. So, that is the way whatever is the centreline is coming from the
taxiway if it reaches the runway strip, then at the edge of that runway strip it will be
terminated, will be stopped. At all other intersections with the runway, the centreline of
the taxiway extends up to the centreline of the runway. So, we will be looking at these
types of ways in which these markings are provided.
(Refer Slide Time: 49:04)
At the taxiway intersection, the centreline marking of the taxiway continue through the
intersection area. So, if it is only a taxiway intersection, then that can cross each other.
For taxiway intersection where there is a need to hold the aircraft, a dashed yellow
holding line is placed perpendicular to and across the centreline of both taxiways. So, that
is that particular line we defined, that aircraft needs to be stopped by this position, if it is
required.

(Refer Slide Time: 49:39)
Similarly, at the intersection of runway with an exit taxiway, the taxiway markings are
extended on to the runway parallel to the runway centreline, marking a distance of 60
meters beyond the point of tangency that is with respect to the exit taxiway and runway
connectivity. If a taxiway crosses a runway, the taxiway markings may continue across
the runway, but with interruption for the runway markings. So, the runway markings
should remain clearly visible and there should not be any vagueness in understanding
those markings with respect to the crossing markings being provided for taxiways.

(Refer Slide Time: 50:24)
When the edge of full strength pavement of the taxiway is not readily apparent, the edge
of the taxiway is marked with two continuous 15 centimeter wide yellow stripes which
are 15 centimeter apart.
(Refer Slide Time: 50:40)
So, here we can look at these markings in a diagrammatic form. This is the diagram
which tries to show the markings with respect to this runway stripe. This is the runway

stripe, the markings we have already discussed. Here, there is a taxiway, there is an exit
taxiway being provided. So, this is the centreline of the exit taxiway which is going and
ends at the edge of the runway stripe. This is what we have already discussed. Here, there
is a holding line which is provided and if an aircraft is to be stopped then, it is to be
stopped by this point, so that there is no problem as far as the operation on this runway
stripe is concerned.

(Refer Slide Time: 51:23)
This is another diagram which tries to define the connectivity of the runway strip with
this taxiway and here, the centreline markings have been extended up to the centreline of
the runway strip, but are displaced by a distance of 0.9 meters from that one and there is
some distance by which it continues parallel to the centreline marking of the runway strip
that is D, which is minimum 60 meters and the rest of the things are as such and this
holding line is at a distance of minimum 30 meters from the end of the. from the edge of
this runway stripe.

(Refer Slide Time: 52:06)
This is a crossing of two taxiways and therefore, it is permitted that the lines of or
markings of the taxiways may cross each other as been shown here. So, these are the two
centrelines which are crossing each other.
(Refer Slide Time: 52:25)

This is another diagram which tries to provide the connectivity between the runway strip
and this is the exit taxiway which is perpendicular to runway strip. Here, the centreline of

this taxiway is going and it extends again for a 60 meter minimum distance on this side as
well as 60 meter minimum distance on this side and becomes, remains parallel to the
centreline of the runway strip.
(Refer Slide Time: 52:57)
This is another big diagram which tries to show the various types of connectivities. We
have the runway stripe on this side. We have the exit taxiway being provided at the end
of this runway strip, then there is perpendicular taxiway being provided to this runway
strip and then there is an exit taxiway, rapid exit taxiway being provided here, by which
the aircraft which is coming in this direction can move away. So, all the three conditions
with respect to the runway stripes have been depicted and the linings have been shown.
At the same time, there is a crossing which is being shown here, which is with respect to
this exit taxiway and another parallel taxiway being provided with respect to this runway
strip. So, the connectivities as well as the various markings have been shown at this
location also.

(Refer Slide Time: 53:55)
This is a diagrammatic view of the holding position markings and its ….. condition by
which we can provide. There are two ways in which it can be done - the two parallel lines
with the two segmented lines, whereas here it is two parallel lines which are jointed
together by the perpendicular lines being located by a pair of perpendicular lines located
towards the ends as well as the center.
(Refer Slide Time: 54:26)

Now, we look at another type of airport marking which is closed runway or taxiway
marking. In the case this is for temporarily closed runways, then it is, yellow crosses are
placed at the two ends which defines that it is temporarily closed. In case it is
permanently closed, then the yellow cross one at each runway end and at 300 meters
intervals are placed and the threshold runway designation and touch down markings are
obliterated. For temporarily closed taxiways, barricades with orange and white markings
are general used. In case there is a permanently closed taxiway, then a cross is placed at
each entrance to the taxiway.
(Refer Slide Time: 55:18)
This is the way generally we do this closed runway or taxiway marking. Here we can see
that this is a cross being provided, the dimensions are been shown here that is 1.8 meter
wide with this distance is 14.5 meters and this distance is 35 meters and this is another
type of marking which is provided. This is for basically the closed taxiway marking
which is provided. This is for basically the closed taxiway marking. So, this is for closed
runway marking and this is for closed taxiway marking. So, this is what is related to the
various types of markings which are provided on any of the airport in the form of the
visual aids which helps the pilots to do certain operation like take-off and landings.
In the case of landings they are more important, because the safety is to be ensured at the
time of landing as well as at the time when the speed of that aircraft needs to be reduced
by reaching the exit taxiway or rapid exit taxiways. So, this is the point at which we will
be closing our discussion regarding the visual aids and we continue the same in the
coming lecture. Till then, good bye and thank you to you.