B.

TECH (3rd Year)

CEC-3170: TRANSPORTATION ENGINEERING

(TRAFFIC & AIRPORT ENGINEERING)

By:
Dr. Aparna Kanth

Ph. D (IIT Roorkee)

M. Tech (IIT Delhi)
B. Tech (AMU)
CEC-3170: TRANSPORTATION: Traffic & Airport Engineering
COURSE CONTENT

• UNIT 1 Highway Material & Construction: Properties of sub-grade & pavement component
material, test on stone aggregates & bituminous materials. Highway Construction: WBM, WMM,
Bituminous & cement concrete pavements.
• UNIT 2 Highway Geometric & Pavement Design: Design of geometric elements of road,
Design factors for flexible and rigid pavements. Group Index and CBR methods for flexible
pavement design. Analysis for wheel load stresses in rigid pavement. Westergaard’s method for
design of rigid pavement.
• UNIT 3 Railway Engineering: Gauges, rail failure and ultrasonic inspection, rail joints & welding
of rails, wear of rails, sleepers, ballast & formation, points & crossings, station & yard, tractive
resistances, hauling capacity of locomotive, modernization of railways.
• UNIT 4 Traffic & Airport Engineering: Traffic studies, intersection design, traffic signs &
signals, selection of site for an airport, airport obstructions, imaginary surfaces, runway
orientation, wind rose diagram, design of runway, basic runway length, corrections of
runway length, airport classification, geometric design, airport capacity, aircraft parking
systems, wind and landing direction indicators.
CEC-3170: TRANSPORTATION: Traffic & Airport Engineering
INTERSECTION

Intersection is an area shared by two or more roads. This area is

designated for the vehicles to turn to different directions to reach their
desired destinations. Its main function is to guide vehicles to their
respective directions.

• Drivers have to make split second decision at an intersection by considering his route,
intersection geometry, speed and direction of other vehicles etc., else ACCIDENT.
• Overall traffic flow depends on the performance of the intersections. It also affects
the CAPACITY of the road.

CEC-3170: TRANSPORTATION: Traffic & Airport Engineering

TRAFFIC ROTARIES

• Rotary intersections or round abouts are

special form of at-grade intersections laid
out for the movement of traffic in one
direction around a central traffic island.
• Essentially all the major conflicts at an
intersection namely the collision between
through and right-turn movements are
converted into milder conflicts namely
merging and diverging.
• The vehicles entering the rotary are gently
forced to move in a clockwise direction in
orderly fashion. They then weave out of the
rotary to the desired direction.
CEC-3170: TRANSPORTATION: Traffic & Airport Engineering
ADVANTAGES OF TRAFFIC ROTARIES

• Traffic flow is regulated to only one direction of movement, thus eliminating severe
conflicts between crossing movements.
• All the vehicles entering the rotary are gently forced to reduce the speed and continue to
move at slower speed. Thus, none of the vehicles need to be stopped, unlike in a
signalized intersection.
• Because of lower speed of negotiation and elimination of severe conflicts, accidents and
their severity are much less in rotaries.
• Rotaries are self governing and do not need practically any control by police or traffic
signals.
• They are ideally suited for moderate traffic, especially with irregular geometry, or
intersections with more than three or four approaches.

CEC-3170: TRANSPORTATION: Traffic & Airport Engineering

LIMITATIONS OF TRAFFIC ROTARIES

• All the vehicles are forced to slow down and negotiate the intersection. Therefore,
the cumulative delay will be much higher than channelized intersection.
• Even when there is relatively low traffic, the vehicles are forced to reduce their
speed.
• Rotaries require large area of relatively flat land making them costly at urban areas.
• The vehicles do not usually stop at a rotary. They accelerate and exit the rotary at
relatively high speed.
• Therefore, they are not suitable when there is high pedestrian movements.

CEC-3170: TRANSPORTATION: Traffic & Airport Engineering

GUIDELINES FOR SELECTION OF TRAFFIC ROTARIES

• Rotaries are suitable when the traffic entering from all the four approaches are
relatively equal.
• A total volume of about 3000 vehicles per hour can be considered as the upper
limiting case and a volume of 500 vehicles per hour is the lower limit.
• A rotary is very beneficial when the proportion of the right-turn traffic is very high;
typically if it is more than 30 percent.
• Rotaries are suitable when there are more than four approaches or if there is no
separate lanes available for right-turn traffic. Rotaries are ideally suited if the
intersection geometry is complex.

CEC-3170: TRANSPORTATION: Traffic & Airport Engineering

TRAFFIC OPERATIONS IN A ROTARY

The traffic operations at a rotary are three; diverging, merging and weaving. All the
other conflicts are converted into these three less severe conflicts.
1. Diverging: It is a traffic operation when the vehicles moving in one direction is
separated into different streams according to their destinations.
2. Merging: Merging is the opposite of diverging. Merging is referred to as the
process of joining the traffic coming from different approaches and
going to a common destination into a single stream.
3. Weaving: Weaving is the combined movement of both merging and
diverging movements in the same direction.

CEC-3170: TRANSPORTATION: Traffic & Airport Engineering

DESIGN ELEMENTS OF ROTARY

1. Design Speed: All the vehicles are required to

reduce their speed at a rotary. The normal
practice is to keep the design speed as 30 and 40
kmph for urban and rural areas respectively.

2. Entry Radius: The radius at the entry

depends on various factors like design speed,
super-elevation, and coefficient of friction.
The entry to the rotary is not straight, but a
small curvature is introduced. This will
force the driver to reduce the speed. The entry
radius of about 20 and 25 metres is ideal for an
urban and rural design respectively.

CEC-3170: TRANSPORTATION: Traffic & Airport Engineering

DESIGN ELEMENTS OF ROTARY cont…

3. Exit Radius: The exit radius should be higher than the entry radius and the radius
of the rotary island so that the vehicles will discharge from the rotary at a higher rate.
A general practice is to keep the exit radius as 1.5 to 2 times the entry radius.
However, if pedestrian movement is higher at the exit approach, then the exit radius
could be set as same as that of the entry radius.

4. Island Radius: The radius of the central island is governed by the design speed, and
the radius of the entry curve. The radius of the central island, in practice, is given a
slightly higher radius so that the movement of the traffic already in the rotary will
have priority. The radius of the central island which is about 1.3 times that of the
entry curve is adequate for all practical purposes.

CEC-3170: TRANSPORTATION: Traffic & Airport Engineering

DESIGN ELEMENTS OF ROTARY cont…

5. Width of Rotary: The entry width and exit width of the rotary is governed by the traffic
entering and leaving the intersection and the width of the approaching road. The width of the
carriageway at entry and exit will be lower than the width of the carriageway at the approaches
to enable reduction of speed. IRC suggests that a two lane road of 7 m width should be kept as
7 m for urban roads and 6.5 m for rural roads. Further, a three lane road of 10.5 m is to be
reduced to 7 m and 7.5 m respectively for urban and rural roads.

The width of the weaving section should be higher than the width at entry and exit. Normally
this will be one lane more than the average entry and exit width. Thus weaving width is given as,

where e1 is the width of the carriageway at the entry and e2 is the carriageway width at exit.
CEC-3170: TRANSPORTATION: Traffic & Airport Engineering
DESIGN ELEMENTS OF ROTARY cont…

6. Weaving length: Weaving length determines how smoothly the traffic can merge and
diverge. It is decided based on many factors such as weaving width, proportion of weaving
traffic to the non-weaving traffic etc. This can be best achieved by making the ratio of
weaving length to the weaving width very high. A ratio of 4 is the minimum value
suggested by IRC. Very large weaving length is also dangerous, as it may encourage over-
speeding.

CEC-3170: TRANSPORTATION: Traffic & Airport Engineering

DESIGN ELEMENTS OF ROTARY cont…

7. Capacity: The capacity of rotary is determined by the capacity of each weaving

section. Transportation road research lab (TRL) proposed the following empirical
formula to find the capacity of the weaving section.

where e is the average entry and exit width, i.e, (e1+e2)/2

w is the weaving width,
l is the length of weaving, and
p is the maximum proportion of weaving traffic to the non-weaving traffic.

CEC-3170: TRANSPORTATION: Traffic & Airport Engineering

DESIGN ELEMENTS OF ROTARY cont…

Below Figure shows four types of movements at a weaving section, a and d are the non-
weaving traffic and b and c are the weaving traffic. Therefore,

= Weaving traffic/Total traffic

b: Crossing/weaving traffic turning towards right while entering the rotary

c: Crossing/weaving traffic turning towards left while entering the rotary
a: Left turning traffic moving along left extreme lane
d: Right turning traffic moving along right extreme lane

CEC-3170: TRANSPORTATION: Traffic & Airport Engineering

DESIGN ELEMENTS OF ROTARY cont…

This capacity formula is valid only if the following conditions are satisfied.

1. Weaving width at the rotary is in between 6 and 18 metres.

2. The ratio of average width of the carriage way at entry and exit to the
weaving width is in the range of 0.4 to 1.
3. The ratio of weaving width to weaving length of the roundabout is in between
0.12 and 0.4.
4. The proportion of weaving traffic to non-weaving traffic in the rotary is in the
range of 0.4 and 1.
5. The weaving length available at the intersection is in between 18 and 90 m.

CEC-3170: TRANSPORTATION: Traffic & Airport Engineering

4-LEGGED ROTARY SECTION

CEC-3170: TRANSPORTATION: Traffic & Airport Engineering

DESIGN PROBLEM

QUES: The width of a carriage

way approaching an intersection
is given as 15 m. The entry and
exit width at the rotary is 10 m.
The traffic approaching the
intersection from the four sides
is shown in the figure. Find the
capacity of the rotary using the
given data?
CEC-3170: TRANSPORTATION: Traffic & Airport Engineering
DESIGN PROBLEM cont…

SOLUTION:

CEC-3170: TRANSPORTATION: Traffic & Airport Engineering

DESIGN PROBLEM cont…

CEC-3170: TRANSPORTATION: Traffic & Airport Engineering

DESIGN PROBLEM cont…

CEC-3170: TRANSPORTATION: Traffic & Airport Engineering

DESIGN PROBLEM

QUES: The width of approaches for a rotary intersection is

12 m. The entry and exit width at the rotary is 10 m. Table
below gives the traffic from the four approaches, traversing
the intersection. Find the capacity of the rotary.

CEC-3170: TRANSPORTATION: Traffic & Airport Engineering

DESIGN PROBLEM cont…

SOLUTION:

CEC-3170: TRANSPORTATION: Traffic & Airport Engineering

DESIGN PROBLEM cont…

CEC-3170: TRANSPORTATION: Traffic & Airport Engineering

DESIGN PROBLEM cont…

CEC-3170: TRANSPORTATION: Traffic & Airport Engineering

BASICS OF TRAFFIC CONTROL DEVICES

• Traffic control device is the medium used for communicating between

traffic engineer and road users. Unlike other modes of transportation,
there is no control on the drivers using the road. Here traffic control
devices comes to the help of the traffic engineer.
• Traffic control devices direct, guide, and inform drivers by offering visual
or tactile indicators.
• The main traffic control devices—signs, signals, road markings, and
barricades or channelizers— keep drivers and pedestrians safe.

CEC-3170: TRANSPORTATION: Traffic & Airport Engineering

TRAFFIC CONTROL DEVICES ON PUBLIC ROADS

• Signs Road signs provide local information to drivers. Made from reflective material in
high-contrast colors. Signs may use words and symbols.
➢ Regulatory signs: They declare the accepted legal use of the immediate public roadway.
➢ Warning signs: Allow drivers to be aware of driving hazards like animal crossings or
twisting paths.
➢ Guiding or informational signs: Provide route and amenity information.
➢ Traffic signs: For the traffic control landscape.

CEC-3170: TRANSPORTATION: Traffic & Airport Engineering

TRAFFIC CONTROL DEVICES ON PUBLIC ROADS cont…

• Road Markings & Construction

• Road markings: Like lines and arrows, are used to mark correct legal usage
of road surfaces. They include stop lines, lane markers, turn lane arrows, and
more.
• Road construction: Rumble strips can mark lanes. When a car drifts over
them, they alert through sound and texture that the vehicle is no longer in its
lane. Rumble strips are often used in places where drivers might miss a sharp
bend in the road, or on long stretches where a driver might fall asleep.

CEC-3170: TRANSPORTATION: Traffic & Airport Engineering

TRAFFIC CONTROL DEVICES ON PUBLIC ROADS cont…

• Barriers & Channelizers: Control traffic, warn against hazards, and mitigate accidents.
➢ Traffic delimiters & cones: are often placed temporarily to provide warning around
hazards or work zones.
➢ Highway barriers: help prevent head-on collisions and mark lanes.
➢ Channelizers & road barriers: are more permanent than traffic delimiters or
cones—though some may be removable for multi-access spaces.

CEC-3170: TRANSPORTATION: Traffic & Airport Engineering

TRAFFIC CONTROL DEVICES ON PRIVATE FACILITIES

• Signs Road signs provide local information to drivers. Made from reflective material in
high-contrast colors. Signs may use words and symbols.
➢ Regulatory signs: They declare the accepted legal use of the immediate public roadway.
➢ Warning signs: Allow drivers to be aware of driving hazards like animal crossings or
twisting paths.
➢ Guiding or informational signs: Provide route and amenity information.
➢ Traffic signs: For the traffic control landscape.

CEC-3170: TRANSPORTATION: Traffic & Airport Engineering

REQUIREMENTS OF TRAFFIC CONTROL DEVICES

1. The control device should fulfill a need: Each device must have a specific purpose
for the safe and efficient operation of traffic flow.
2. It should command attention from the road users: For commanding attention, proper
visibility should be there. Also the sign should be distinctive and clear.
3. It should convey a clear, simple meaning: Clarity and simplicity of message is
essential for the driver even if he is less educated should properly understand the
meaning in short time.
4. Road users must respect the signs: Respect is commanded only when the drivers are
conditioned to expect that all devices carry meaningful and important messages.
Overuse, misuse and confusing messages of devices tends the drivers to ignore them.
5. The control device should provide adequate time for proper response from the
road users: The sign boards should be placed at a distance such that the driver could
see it and gets sufficient time to respond to the situation. For example, the STOP sign
which is always placed at the stop line of the intersection should be visible for atleast
one safe stopping sight distance away from the stop line.
CEC-3170: TRANSPORTATION: Traffic & Airport Engineering
COMMUNICATION TOOLS

A number of mechanisms are used by the traffic engineer to communicate with the
road user.

1. Color: The most commonly used colors are red, green, yellow, black, blue, and
brown .
2. Shape: The categories of shapes normally used are circular, triangular,
rectangular, and diamond shape. Two exceptional shapes used in traffic signs are
octagonal shape for STOP sign and use of inverted triangle for GIVE WAY (YIELD)
sign. Diamond shape signs are not generally used in India
3. Legend: For the easy understanding by the driver, the legend should be short,
simple and specific so that it does not divert the attention of the driver. Symbols are
normally used as legends so that even a person unable to read the language will
be able to understand that.
4. Pattern: Generally solid, double solid and dotted lines are used. Each pattern
conveys different type of meaning.
CEC-3170: TRANSPORTATION: Traffic & Airport Engineering
TYPES OF TRAFFIC SIGNS

• The major types of traffic control devices used are- traffic signs, road markings , traffic signals and
parking control.
• Different types of traffic signs are
• Regulatory signs: These signs require the driver to obey the signs for the safety of other road
users.
• Warning sign: These signs are for the safety of oneself who is driving and advice the drivers to
obey these signs
• Informatory signs: These signs provide information to the driver about the facilities available
ahead, and the route and distance to reach the specific destinations

In addition special type of traffic sign namely work zone signs are also available. These type of signs are
used to give warning to the road users when some construction work is going on the road. They are
placed only for short duration and will be removed soon after the work is over and when the road is
brought back to its normal condition.
CEC-3170: TRANSPORTATION: Traffic & Airport Engineering
REGULATORY SIGNS

These signs are also called mandatory signs because it is mandatory that the drivers must obey these
signs, else the control agency has the right to take legal action against the driver. These signs have
generally black legend on a white background. They are circular in shape with red borders. They are
classified as:
• Right of way series: They are the STOP sign and GIVE WAY sign.
• Speed series: Number of speed signs may be used to limit the speed of the vehicle on the road.
They include typical speed limit signs, truck speed, minimum speed signs etc.
• Movement series: These include turn signs, alignment signs, exclusion signs, one way signs etc.
• Parking series: They indicate not only parking prohibitions or restrictions, but also indicate
places where parking is permitted, the type of vehicle to be parked, duration for parking etc.
• Pedestrian series: These signs are meant for the safety of pedestrians and include signs
indicating pedestrian only roads, pedestrian crossing sites etc.
• Miscellaneous: It includes ”KEEP OF MEDIAN” sign, signs indicating road closures, signs
restricting vehicles carryingCEC-3170:
hazardous cargo, signs indicating vehicle weight limitations etc.
TRANSPORTATION: Traffic & Airport Engineering
INFORMATORY SIGNS

▪ Informative signs also called guide signs, are provided to assist the drivers to reach their desired
destinations.
▪ These are predominantly meant for the drivers who are unfamiliar to the place. The guide signs
are redundant for the users who are accustomed to the location.
▪ Examples are route markers, destination signs, mile posts, service information, etc.
▪ Route markers are used to identify numbered highways. They are written black letters on
yellow background.
▪ Destination signs are used to indicate the direction to the critical destination points, and to
mark important intersections. Distance in kilometers are sometimes marked to the right side of
the destination. They are, in general, rectangular with the long dimension in the horizontal
direction. They are color coded as white letters with green background.
▪ Mile posts are provided to inform the driver about the progress along a route to reach his
destination. Service guide signs give information to the driver regarding various services such as
food, fuel, medical assistance etc. They are written with white letters on blue background.
CEC-3170: TRANSPORTATION: Traffic & Airport Engineering
WARNING SIGNS

Warning signs or cautionary signs

give information to the driver about
the impending road condition. They
advice the driver to obey the rules.
These signs are meant for the own
safety of drivers. They call for extra
vigilance from the part of drivers.
The color convention used for this
type of signs is that the legend will
be black in color with a white
background. The shape used is
upward triangular or diamond
shape with red borders.

CEC-3170: TRANSPORTATION: Traffic & Airport Engineering

TRAFFIC SIGNALS

▪ The conflicts arising from movements of traffic in different directions is solved by

time sharing of the principle.
▪ The advantages of traffic signal includes an orderly movement of traffic, an
increased capacity of the intersection and requires only simple geometric
design.
▪ The disadvantages of the signalized intersection are it affects larger stopped
delays, and the design requires complex considerations. Although the overall
delay may be lesser than a rotary for a high volume, a user is more concerned
about the stopped delay.
CEC-3170: TRANSPORTATION: Traffic & Airport Engineering
DEFINITION & NOTATIONS

▪ Cycle: A signal cycle is one complete rotation through all of the indications provided.
▪ Cycle length: Cycle length is the time in seconds that it takes a signal to complete one
full cycle of indications. It indicates the time interval between the starting of of green for
one approach till the next time the green starts. It is denoted by C.
▪ Interval: Thus it indicates the change from one stage to another. There are two types of
intervals change interval and clearance interval. Change interval is also called the
yellow time indicates the interval between the green and red signal indications for an
approach. Clearance interval is also called all red is included after each yellow interval
indicating a period during which all signal faces show red and is used for clearing off the
vehicles in the intersection
CEC-3170: TRANSPORTATION: Traffic & Airport Engineering
DEFINITION & NOTATIONS cont…

▪ Green interval: It is the green indication for a particular movement or set of

movements and is denoted by Gi. This is the actual duration the green light of a
traffic signal is turned on.
▪ Red interval: It is the red indication for a particular movement or set of
movements and is denoted by Ri. This is the actual duration the red light of a
traffic signal is turned on.
▪ Phase: A phase is the green interval plus the change and clearance intervals
that follow it. Thus, during green interval, non conflicting movements are
assigned into each phase. It allows a set of movements to flow and safely halt
the flow before the phase of another set of movements start.
CEC-3170: TRANSPORTATION: Traffic & Airport Engineering
DEFINITION & NOTATIONS cont…

▪ Yellow time (Amber time): It is the time after green interval before the signal
turns red. If not given, it is assumed to be 2 sec.
▪ Lost time: It indicates the time during which the intersection is not effectively
utilized for any movement. For example, when the signal for an approach turns
from red to green, the driver of the vehicle which is in the front of the queue, will
take some time to perceive the signal (usually called as reaction time) and some
time will be lost here before he moves.

CEC-3170: TRANSPORTATION: Traffic & Airport Engineering

PHASE

Multiple movements done at a time is considered as one phase. In one cycle length,
there may be ‘n’ number of phases.
(Left turn traffic is always allowed.)
Cycle length = Time for all phases

CEC-3170: TRANSPORTATION: Traffic & Airport Engineering

PHASE DESIGN

The signal design procedure involves six major steps. They include the:
(1) Phase design,
(2) Determination of amber time and clearance time,
(3) Determination of cycle length,
(4) Apportioning of green time,
(5) Pedestrian crossing requirements, and
(6) The performance evaluation of the above design.
The objective is to design phases with minimum conflicts or with less severe conflicts.
There is no precise methodology for the design of phases. This is often guided by the
geometry of the intersection, flow pattern especially the turning movements, the relative
magnitudes of flow. Therefore, a trial and error procedure is often adopted.
CEC-3170: TRANSPORTATION: Traffic & Airport Engineering
PHASE DESIGN

To illustrate various phase plan options, consider a four legged intersection with through
traffic and right turns. Left turn is ignored.

The first issue is to decide how many phases are required. It is possible to have two, three,
four or even more number of phases.
(1) Two Phase Signals,
(2) Four Phase Signals CEC-3170: TRANSPORTATION: Traffic & Airport Engineering
TWO-PHASE SIGNALS

• Two phase system is usually adopted if through traffic is significant compared to the
turning movements. For example in figure, non-conflicting through traffic 3 and 4 are
grouped in a single phase and non-conflicting through traffic 1 and 2 are grouped in
the second phase. However, in the first phase flow 7 and 8 offer some conflicts and
are called permitted right turns. Needless to say that such phasing is possible only if
the turning movements are relatively low. On the other hand, if the turning movements
are significant ,then a four phase system is usually adopted.

43
CEC-3170: TRANSPORTATION: Traffic & Airport Engineering
FOUR-PHASE SIGNALS

• There are at least three possible

phasing options. For example, figure
shows the most simple and trivial
phase plan. where, flow from each
approach is put into a single phase
avoiding all conflicts. This type of
phase plan is ideally suited in urban
areas where the turning movements
are comparable with through
movements and when through traffic
and turning traffic need to share
same lane. This phase plan could be
very inefficient when turning
movements are relatively low.
44
CEC-3170: TRANSPORTATION: Traffic & Airport Engineering
FOUR-PHASE SIGNALS cont…

• Figure shows a second possible

phase plan option where opposing
through traffic are put into same
phase. The non-conflicting right turn
flows 7 and 8 are grouped into a third
phase. Similarly flows 5 and 6 are
grouped into fourth phase. This type
of phasing is very efficient when the
intersection geometry permits to
have at least one lane for each
movement, and the through traffic
volume is significantly high.

45
CEC-3170: TRANSPORTATION: Traffic & Airport Engineering
FOUR-PHASE SIGNALS cont…

• Figure shows yet another phase plan.

However, this is rarely used in practice.
There are five phase signals, six phase
signals etc. They are normally provided if
the intersection control is adaptive, that is,
the signal phases and timing adapt to the
real time traffic conditions.

46
CEC-3170: TRANSPORTATION: Traffic & Airport Engineering
METHODS TO DESIGN SIGNALS

There are three methods for designing signals:

• Trial Cycling Method:

• Approximation Method: Pedestrians are included, traffic signal timing is
decided considering the total taken by pedestrians to cross the roads as
well as the time required by the vehicles to cross the intersection.
• IRC Method: It is a combination of approximation and Webster Method.
Here the traffic signal is designed using Approximation Method and the
validity of minimum green time is checked using Webster Method. Check
which method is giving higher green time and higher total cycle time.
• Webster Method:

47
CEC-3170: TRANSPORTATION: Traffic & Airport Engineering
WEBSTER METHOD

• Sum of ratio of normal flow to saturated flow value for roads A and B:
Y = yA + yB
Where, yA = qA/SA and yB = qB/SB
Saturated flow value (SA and SB) is dependent on road width: (veh/hr/lane)

Road width 3 3.5 4 4.5 5 5.5 >5.5

SFV 1850 1890 1950 2250 2550 2990 525 veh/hr/meter width of road

• Total lost time:

L = 2n + R
Where, n – no. of phase system, R – Red time
• Optimum cycle time:
Co = (1.5L + 5)/(1-Y) sec
• Green time required:
GA = yA*(Co-L)/Y

GB = yB*(Co-L)/Y
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NUMERICAL

49
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SOLUTION

• qA = 465 veh/hr/lane (max. value)

• qB = 350 veh/hr/lane (max. value)
• SA = 525 * 15/4 = 1969 veh/hr/lane
• SB = 1950 veh/hr/lane
Now, yA = qA/SA = 465/1969 = 0.236
and yB = qB/SB = 350/1950 = 0.18
• Therefore, Sum of ratio of normal flow to saturated flow value for roads A
and B:
Y = yA + yB = 0.236 + 0.18 = 0.416
• Total lost time:
L = 2n + R = 2*2 + 15 = 19 sec
Where, n – no. of phase system = 2, R – Red time = 15 sec
50
CEC-3170: TRANSPORTATION: Traffic & Airport Engineering
SOLUTION

51
CEC-3170: TRANSPORTATION: Traffic & Airport Engineering
INTERVAL DESIGN

• There are two intervals, namely the change interval and clearance interval,
normally provided in a traffic signal. The change interval or yellow time is provided
after green time for movement. The purpose is to warn a driver approaching the
intersection during the end of a green time about the coming of a red signal. They
normally have a value of 3 to 6 seconds. The design consideration is that a driver
approaching the intersection with design speed should be able to stop at the stop line
of the intersection before the start of red time. Institute of transportation engineers
(ITE) has recommended a methodology for computing the appropriate length of
change interval which is as follows:

where y is the length of yellow interval in seconds, t is the reaction time of the driver, v85
is the 85th percentile speed of approaching vehicles in m/s, a is the deceleration rate of
vehicles in m/s2, g is the grade of approach expressed as a decimal. 52
CEC-3170: TRANSPORTATION: Traffic & Airport Engineering
INTERVAL DESIGN cont…

• Change interval can also be approximately computed as

y = SSD v
where SSD is the stopping sight distance and v is the speed of the vehicle. The
clearance interval is provided after yellow interval and as mentioned earlier, it is used to
clear off the vehicles in the intersection. Clearance interval is optional in a signal design.
It depends on the geometry of the intersection. If the intersection is small, then there is
no need of clearance interval whereas for very large intersections, it may be provided.

85th Percentile Speed (mph) – The 85th percentile speed is the speed at or below which 85
percent of the drivers travel on a road segment. Motorists traveling above the 85th percentile
speed are considered to be exceeding the safe and reasonable speed for road and traffic
conditions.
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CYCLE TIME

• Cycle time is the time taken by a signal to complete one full cycle of iterations.
i.e. one complete rotation through all signal indications. It is denoted by C.
• Vehicles depart from an intersection when the green signal is initiated: As the
signal is initiated, the time interval between two vehicles, referred as headway,
crossing the curb line is noted. The first headway is the time interval between the
initiation of the green signal and the instant vehicle crossing the curb line.
• After few vehicles, the headway will become constant. This constant headway
which characterizes all headways beginning with the fourth or fifth vehicle, is
defined as the saturation headway, and is denoted as h. This is the headway
that can be achieved by a stable moving platoon of vehicles passing through a
green indication. If every vehicles require h seconds of green time, and if the
signal were always green, then s vehicles/per hour would pass the intersection.
54
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CYCLE TIME cont…

Where, s is the saturation flow rate in vehicles per hour

of green time per lane, h is the saturation headway in
seconds.

As noted earlier, the headway will be more than h

particularly for the first few vehicles. The difference
between the actual headway and h for the ith vehicle
and is denoted as ei shown in figure

55
CEC-3170: TRANSPORTATION: Traffic & Airport Engineering
CYCLE TIME cont…

• These differences for the first few vehicles can be added to get start up lost
time, l1 which is given by,

The green time required to clear N vehicles can be found out as,

where T is the time required to clear N vehicles through signal, l1 is the start-up
lost time, and h is the saturation headway in seconds.

56
CEC-3170: TRANSPORTATION: Traffic & Airport Engineering
EFFECTIVE GREEN TIME

• Effective green time is the actual time available for the vehicles to
cross the intersection. It is the sum of actual green time (Gi) plus the
yellow minus the applicable lost times. This lost time is the sum of
start-up lost time (l1) and clearance lost time (l2) denoted as tL. Thus
effective green time can be written as,

57
CEC-3170: TRANSPORTATION: Traffic & Airport Engineering
LANE CAPACITY

• The ratio of effective green time to the cycle length (gi/C )is defined as green ratio.
We know that saturation flow rate is the number of vehicles that can be moved in one
lane in one hour assuming the signal to be green always. Then the capacity of a lane
can be computed as,

where ci is the capacity of lane in vehicle per hour, si is the saturation flow rate in
vehicle per hour per lane, C is the cycle time in seconds.

58
CEC-3170: TRANSPORTATION: Traffic & Airport Engineering
NUMERICAL

59
CEC-3170: TRANSPORTATION: Traffic & Airport Engineering
NUMERICAL

60
CEC-3170: TRANSPORTATION: Traffic & Airport Engineering
CRITICAL LANE

During any green signal phase, several lanes on one or more approaches are
permitted to move. One of these will have the most intense traffic. Thus it
requires more time than any other lane moving at the same time. If sufficient
time is allocated for this lane, then all other lanes will also be well
accommodated. There will be one and only one critical lane in each signal
phase. The volume of this critical lane is called critical lane volume.

61
CEC-3170: TRANSPORTATION: Traffic & Airport Engineering
DETERMINATION OF CYCLE LENGTH

Start up lost time for phase i: tLi

Total Start up lost time for N phases: L =
If tLi is same for all phases: L = NtL
If C is the cycle length in seconds, No. of cycles per hour = 3600/C
Total lost time per hour = No. of cycle per hr times lost time per hr = 3600L/C
= 3600NtL/C
Total effective green time available for the movement in an hour
= 1 hour – Total lost time in an hr

62
CEC-3170: TRANSPORTATION: Traffic & Airport Engineering
DETERMINATION OF CYCLE LENGTH cont…

Let the total number of critical lane volume that can be accommodated per hour is
given by Vc = Tg/h

63
CEC-3170: TRANSPORTATION: Traffic & Airport Engineering
DETERMINATION OF CYCLE LENGTH cont…

The above equation is based on the assumption that there will be uniform flow of
traffic in an hour. To account for the variation of volume in an hour, a factor called
peak hour factor, (PHF) which is the ratio of hourly volume to the maximum flow
rate, is introduced. Another ratio called v/c ratio indicating the quality of service is
also included in the equation.

64
CEC-3170: TRANSPORTATION: Traffic & Airport Engineering
DETERMINATION OF CYCLE LENGTH cont…

Highway capacity manual (HCM) has given an equation for determining the cycle
length which is a slight modification of the above equation.

Where N is the number of phases, L is the lost time per phase, (V/s)i is the ratio of
volume to saturation flow for phase i, XC is the quality factor called critical V/C
ratio where V is the volume and C is the capacity.

65
CEC-3170: TRANSPORTATION: Traffic & Airport Engineering
NUMERICAL

The traffic flow in an intersection

is shown in the figure. Given
start-up lost time is 3 seconds,
saturation head way is 2.3
seconds, compute the cycle
length for that intersection.
Assume a two-phase signal.

66
CEC-3170: TRANSPORTATION: Traffic & Airport Engineering
SOLUTION

67
CEC-3170: TRANSPORTATION: Traffic & Airport Engineering
AIRPORT ENGINEERING..
DEFINITION

Transportation engineering is a branch of civil engineering that involves

the planning, design, operation, and maintenance of transportation
systems to help build smart, safe, and livable communities.

• Any system that moves people and goods from one place to another falls under the
scope of transportation engineering, which majorly includes:
– Highways and roadways
– Railways
– Waterways
– Airways
CEC-3170: TRANSPORTATION: Traffic & Airport Engineering
DEFINITION

CEC-3170: TRANSPORTATION: Traffic & Airport Engineering

TYPES OF AIRPORT

CEC-3170: TRANSPORTATION: Traffic & Airport Engineering

INTERNATIONAL AIRPORTS

CEC-3170: TRANSPORTATION: Traffic & Airport Engineering

DOMESTIC AIRPORTS

CEC-3170: TRANSPORTATION: Traffic & Airport Engineering

REGIONAL AIRPORTS

CEC-3170: TRANSPORTATION: Traffic & Airport Engineering

FACTORS AFFECTING SELECTION OF SITE FOR AN AIRPORT

CEC-3170: TRANSPORTATION: Traffic & Airport Engineering

TYPICAL LAYOUT OF AN AIRPORT

CEC-3170: TRANSPORTATION: Traffic & Airport Engineering

IMPORTANT COMPONENTS OF AIRPORT LAYOUT

CEC-3170: TRANSPORTATION: Traffic & Airport Engineering

RUNWAY

CEC-3170: TRANSPORTATION: Traffic & Airport Engineering

TERMINAL BUILDING

An airport terminal is a building at an

airport where passengers can board or
disembark from aircraft, and it's where
they can find services like ticket
counters, baggage handling, and
security checkpoints. The part of the
terminal that provides direct access to
the planes through gates is often
called a concourse.

CEC-3170: TRANSPORTATION: Traffic & Airport Engineering

APRON

An airport apron, also known

as a ramp or tarmac, is the
designated area at an airport
where aircraft are parked,
loaded, unloaded, refueled,
and boarded. It's typically
located adjacent to the
terminal building and serves
as a central point for ground
operations.

CEC-3170: TRANSPORTATION: Traffic & Airport Engineering

TAXIWAY

An airport taxiway is a paved

path connecting runways to
other parts of the airport, like
terminals, hangars, and
aprons. Aircraft use taxiways to
move on the ground,
transitioning between the
runway and these different
areas. They are typically
marked with signage and
lighting for guidance and
safety.
CEC-3170: TRANSPORTATION: Traffic & Airport Engineering
AIRCRAFT STAND

An aircraft stand is a designated

area on an airport's apron where
an aircraft is parked for boarding,
deplaning, or ground handling
activities. These stands are
typically marked with specific
numbers and visual cues to guide
pilots to the correct position.

CEC-3170: TRANSPORTATION: Traffic & Airport Engineering

HANGAR

A "hangar" refers to a large, closed structure designed to house aircraft,

primarily for storage, maintenance, and repair. These buildings offer
protection from the elements and provide a dedicated space for aircraft
operations.

CEC-3170: TRANSPORTATION: Traffic & Airport Engineering

CONTROL TOWER

An airport control tower is a strategically positioned structure that houses

air traffic controllers who direct and monitor aircraft movements on the
ground and in the air within a designated area, such as an airport or a
region of airspace. It's a tall, windowed building with a clear view of
runways, taxiways, and surrounding airspace.

CEC-3170: TRANSPORTATION: Traffic & Airport Engineering

PARKING

Airport parking generally involves

short-term and long-term options,
with varying rates depending on
vehicle type and duration of
stay. Short-term parking is suitable
for pick-ups and drop-offs, while
long-term parking is designed for
extended stays like
vacations. Additionally, some
airports offer cell phone waiting lots
to minimize vehicle dwell time in
passenger pick-up areas.
CEC-3170: TRANSPORTATION: Traffic & Airport Engineering
AIRPORT OBSTRUCTIONS

Imaginary surfaces in airport obstruction are three-dimensional

areas around runways and airports that define safe airspace for
aircraft. These surfaces are used to prevent objects, both natural
and man-made, from extending into airspace where they could
interfere with aircraft operations. They are crucial for ensuring
safe air navigation.

There are basically five imaginary surfaces which the FAA (Federal
Aviation Administration) applies to public-use airports for the
purpose of determining obstructions to air navigation.

CEC-3170: TRANSPORTATION: Traffic & Airport Engineering

IMAGINARY SURFACES

❑ Primary surface: A rectangular horizontal plane

extending from each end of the runway, defining the area
where no obstructions are allowed. It is centered on the
runway, extends 200 feet beyond each end of the runway,
and has a width that varies according to airport-specific
criteria. The elevation of the primary surface corresponds
to the elevation of the nearest point of the runway
centerline.
❑ Approach surface: Slopes outward from the end of
the primary surface, defining the airspace used by aircraft
during approach and landing. The approach surface is
centered on the extended runway centerline, start at each
end of the primary surface (200 feet beyond each end of
the runway), and has a width equal to that of the primary
surface. Approach surfaces slope upward and outward from
the runway ends. CEC-3170: TRANSPORTATION: Traffic & Airport Engineering
TYPES OF IMAGINARY SURFACES

❑ Transitional surface: The transitional surface is a sloping 7:1 surface

that extends outward and upward at right angles to the runway centerline
from the sides of the primary surface and the approach surface.

❑ Horizontal surface: The horizontal surface is a flat, elliptical surface at

an elevation 150 feet above the established airport elevation. The extent of
the horizontal surface is determined by swinging arcs of a 5,000-foot
radius from the center of each end of the primary surface.

❑ Conical surface: The conical surface extends outward and upward from
the horizontal surface at a slope of 20:1 for a horizontal distance of 4,000
feet, further defining the airspace around the airport.

CEC-3170: TRANSPORTATION: Traffic & Airport Engineering

RUNWAY ORIENTATION AND DESIGN

CEC-3170: TRANSPORTATION: Traffic & Airport Engineering

IMPORTANCE OF RUNWAY LAYOUT

CEC-3170: TRANSPORTATION: Traffic & Airport Engineering

RUNWAY NUMBERS

CEC-3170: TRANSPORTATION: Traffic & Airport Engineering

RUNWAY NUMBERS

*FAA: Federal Aviation Administration

CEC-3170: TRANSPORTATION: Traffic & Airport Engineering

RUNWAY CONFIGURATION

CEC-3170: TRANSPORTATION: Traffic & Airport Engineering

PARALLEL RUNWAYS

CEC-3170: TRANSPORTATION: Traffic & Airport Engineering

OPEN-V RUNWAYS

CEC-3170: TRANSPORTATION: Traffic & Airport Engineering

INTERSECTING RUNWAYS

CEC-3170: TRANSPORTATION: Traffic & Airport Engineering

FACTORS AFFECTING RUNWAY ORIENTATION

CEC-3170: TRANSPORTATION: Traffic & Airport Engineering

RUNWAY LIGHTING

CEC-3170: TRANSPORTATION: Traffic & Airport Engineering

RUNWAY LIGHTING

CEC-3170: TRANSPORTATION: Traffic & Airport Engineering

RUNWAY SIGNS

CEC-3170: TRANSPORTATION: Traffic & Airport Engineering

RUNWAY LIGHTING

CEC-3170: TRANSPORTATION: Traffic & Airport Engineering

RUNWAY DESIGN

❑ Runway Orientation
▪ Crosswind
▪ Wind Coverage
▪ Calm Period

❑ Wind Rose Diagram

❑ Runway Length

CEC-3170: TRANSPORTATION: Traffic & Airport Engineering

RUNWAY ORIENTATION

CEC-3170: TRANSPORTATION: Traffic & Airport Engineering

WIND DIRECTION

CEC-3170: TRANSPORTATION: Traffic & Airport Engineering

WIND COVERAGE

❑Wind coverage or usability factor of airport is the percentage of time in a year

during which the cross wind component remains within the limit or runway
system is not restricted because of excessive cross wind.

❑ICAO and FAA recommends minimum wind coverage of 95%.

❑When a single runway or a set of parallel runways cannot be oriented to

provide the required wind coverage, one or more cross wind runways should
be provided.

CEC-3170: TRANSPORTATION: Traffic & Airport Engineering

CALM PERIOD

❑This is the period for which the wind intensity remains below 6.4 km/hr

❑This is common to all directions and hence, can be added to wind coverage for
that direction

❑Calm Period = 100 – Total wind coverage

OR = 100 - ∑Percentage of time wind is blowing in any direction

CEC-3170: TRANSPORTATION: Traffic & Airport Engineering

WIND ROSE DIAGRAM

❑Application of WIND ROSE diagram for finding the orientation of the runway
to achieve wind coverage.

❑The area is divided into 16 parts using an angle of 22.5º

❑Average wind data of 5 to 10 years is used for preparing wind rose diagrams.

CEC-3170: TRANSPORTATION: Traffic & Airport Engineering

TYPES OF WIND ROSE DIAGRAM

CEC-3170: TRANSPORTATION: Traffic & Airport Engineering

APPLICATION OF WIND ROSE DIAGRAM

The following is the average wind data for 10 years. An airport is to be designed for a single runway. Determine the
maximum wind coverage and the best direction of runway. The permissible cross wind component may be assumed
as suitable for mixed category of aircrafts.
Percentage of Time Total in Percentage of Time Total in
Wind each Wind each
Direction 6.4 – 25 25 – 40 40 – 60 direction 6.4 – 25 25 – 40 40 – 60
Direction direction
km/hr km/hr km/hr percent km/hr km/hr km/hr percent
N 7.4 2.7 0.2 10.3 SSW 6.3 3.2 0.5 10.0
NNE 5.7 2.1 0.3 8.1
SW 3.6 1.8 0.3 5.7
NE 2.4 0.9 0.6 3.9
WSW 1.0 0.5 0.1 1.6
ENE 1.2 0.4 0.2 1.8
W 0.4 0.1 0.0 0.5
E 0.8 0.2 0.0 1.0
WNW 0.2 0.1 0.0 0.3
ESE 0.3 0.1 0.0 0.4
SE 4.3 2.8 0.0 7.1 NW 5.3 1.9 0.0 7.2
SSE 5.5 3.2 0.0 8.7 NNW 4.0 1.3 0.3 5.6
S 9.7 4.6 0.0 14.3 TOTAL 86.5
CEC-3170: TRANSPORTATION: Traffic & Airport Engineering
TYPE I WIND ROSE DIAGRAM

▪ It is based on direction and duration of wind.

▪ Minimum eight directions are taken but optimum is 16
directions.
▪ Data includes total percentage of time in each
direction.
▪ Concentric circles are drawn to scale according to the
percentage of time wind is blowing in a direction.
▪ Total percentage in each direction is marked on the
radial line drawn in that direction.
▪ These points on radial lines are joined together to form
a duration map.
▪ Best direction of runway is indicated along the
direction of the longest line on the Wind Rose
diagram.
CEC-3170: TRANSPORTATION: Traffic & Airport Engineering
TYPE II WIND ROSE DIAGRAM

▪ It is based on direction, duration and intensity of wind.

▪ Concentric circles are drawn to scale according to the
wind velocity.
▪ The influence of wind is assumed to spread at an angle
of 22.5º in a direction.
▪ Radial lines, from center, are drawn up to mid point of
two directions thus dividing the space into 16 directions
and 64 parts (blocks).
▪ Categorized duration is marked in the related cell.
▪ Transparent rectangular template of length greater than
the diameter of the diagram and width equal to twice of
allowable cross wind component is made.

CEC-3170: TRANSPORTATION: Traffic & Airport Engineering

TYPE II WIND ROSE DIAGRAM

▪ Wind rose diagram is fixed in position and the template is placed

above it such that center of template coincides with center of
diagram. The center line of template should pass through a direction.
▪ The template is fixed in position and the sum of duration shown in
cells superimposed by the template is calculated. This sum is
shown as percentage and represents the total wind coverage for that
direction.
▪ The template is then rotated and placed in next direction. The total
wind coverage is calculated for that direction too.
▪ Same procedure is adopted for all the directions.
▪ The direction which gives the maximum wind coverage is the
suitable direction for orientation of runway.
▪ If a single runway is not sufficient to provide the necessary coverage
then two or more runways should be planned to get the desired
coverage.
CEC-3170: TRANSPORTATION: Traffic & Airport Engineering
CONDITIONS FOR RUNWAY LENGTH CALCULATION

➢ Length calculated under the following conditions:-

➢ No wind is blowing on runway

➢ Aircraft is loaded with full loading capacity

➢ Airport is at sea level

➢ No wind is blowing on the way to destination

➢ Runway is leveled, i.e zero effective gradient

➢ Standard temperature of 15ºC at the airport

➢ Standard temperature exists along the way

CEC-3170: TRANSPORTATION: Traffic & Airport Engineering

FACTORS AFFECTING RUNWAY LENGTH

➢ Factors affecting the basic runway length –

➢ Aircraft Characteristics

➢ Safety requirements

➢ Airport Environment

CEC-3170: TRANSPORTATION: Traffic & Airport Engineering

AIRCRAFT CHARACTERISTICS

❑ Power and propulsion system

❑ Aircraft Characteristics
❑ Gross Take-off and landing weights of the aircraft
❑ Aerodynamic and Mechanical characteristics
❑ Type of an aircraft
▪ The “critical aircraft” is defined as being the aircraft type which the airport is
intended
▪ to serve and which requires the greatest runway length.
▪ To identify the “critical aircraft”, flight manual performance data of a variety of
aircraft are examined.

CEC-3170: TRANSPORTATION: Traffic & Airport Engineering

SAFETY REQUIREMENTS: NORMAL LANDING

❑ Normal Landing:
▪ The aircraft should come to a stop within 60 percent of landing distance assuming that the
pilot makes an approach at the proper speed and crosses the threshold of the runway at a
height of 15m.
▪ The runway of full strength is to be provided for the entire landing distance.
▪ Normal Landing: Calculations
Field Length(FL) = Landing distance (LD)
LD = Stopping distance (SD)/0.60
Length of full strength runway (FS) = LD

CEC-3170: TRANSPORTATION: Traffic & Airport Engineering

SAFETY REQUIREMENTS: NORMAL TAKE-OFF

❑ Normal Take-off:
▪ The take-off distance must be, for a specific weight of aircraft, 115 percent of the actual distance
the aircraft uses to reach a height of 10.5m.
▪ The distance to reach a height of 10.5m should be equal to 115 percent of the lift- off distance.
▪ It requires a clearway at the end of the runway in the direction of take-off. This should not be
less than 150m wide. The upward slope of clearway from the end of the runway shall not
exceed 1.25 percent.
▪ Normal Take-off: Calculations
Field Length (FL) = Full strength runway(FS) + Clearway (CW)
Take-off distance (TOD) = 1.15D10.5m
Clearway (CW) = 0.5[TOD – 1.15(Lift-off distance, LOD)]
Take-off Run (TOR) = TOD – CW
Length of full strength runway (FS) = Take-off run (TOR)

CEC-3170: TRANSPORTATION: Traffic & Airport Engineering

SAFETY REQUIREMENTS: NORMAL TAKE-OFF

CEC-3170: TRANSPORTATION: Traffic & Airport Engineering

SAFETY REQUIREMENTS: STOPPING IN EMERGENCY

❑ Stopping in Emergency:
▪ For the engine failure case, the take-off distance is the actual distance required to reach a
height of 10.5m with no percentage applied.
▪ It also incidentally recognizes the infrequency of occurrence of the engine failure.
▪ The aircraft accelerates to a speed V1, before finding that the engine has failed and then it
starts decelerating to stop at the end. Therefore, it requires a stopway along with a clearway.
▪ It is required to provide a clearway or a stopway of both in this case.
▪ Stopway is defined as a rectangular paved area at the end of runway in the direction of take-
off.
▪ It is a paved area in which an aircraft can be stopped after an interrupted take-off due to
engine failure.
▪ Its width is at least equal to the width of runway and the thickness of pavement less than that
of the runway, but yet sufficient to take the load of aircraft without failure.

CEC-3170: TRANSPORTATION: Traffic & Airport Engineering

SAFETY REQUIREMENTS: STOPPING IN EMERGENCY

CEC-3170: TRANSPORTATION: Traffic & Airport Engineering

SAFETY REQUIREMENTS: STOPPING IN EMERGENCY

❑ Stopping in Emergency - Calculations

Engine failure, Take-off proceeded case
Field length (FL) = Full strength runway(FS)+Clearway(CW)
Take-off distance (TOD) = D10.5m
Clearway (CW) = 0.5[TOD-LOD]
Take-off Run (TOR) = TOD + CW
Length of full strength runway (FS) = Take-off run (TOR)

Stopping in Emergency - Calculations

Engine Failure, take-off aborted case
Field length(FL) = Full strength runway(FS) + Stopway(SW)
FL = Accelerate stop distance (DAS)

CEC-3170: TRANSPORTATION: Traffic & Airport Engineering

REQUIRED RUNWAY LENGTH

➢ In case of Jet engine: All the three conditions are considered

➢ In case of Piston engine: Only first and third cases are considered
➢ The case giving the longest runway length is finally recommended
➢ Calculation:
Field distance = max {TOD2 , TOD3, DAS, LD}
Full strength runway = max {TOR2, TOR3, LD}
Stopway = DAS – max {TOR2, TOR3, LD}
Clearway = min{(FL – DAS), CL2, CL3}
Stopway min = 0
Clearway min = 0
Clearway max = 300m
CEC-3170: TRANSPORTATION: Traffic & Airport Engineering
AIRPORT ENVIRONMENT

Types of Airport Environment

❑ Atmosphere
▪ Temperature
▪ Surface Wind

❑ Location and Condition of Runway

▪ Altitude
▪ Runway Gradient

CEC-3170: TRANSPORTATION: Traffic & Airport Engineering

AIRPORT ENVIRONMENT: TEMPERATURE

➢ Standard Atmosphere
▪ Temperature at MSL is 15ºC
▪ Pressure at MSL is 760mm of Mercury(Hg)
▪ Air density is 1.225 kg/cu.m
➢ Temperature
▪ Temperature at Mean Sea Level (15ºC)
▪ Airport Reference Temperature (ART)
▪ Standard Temperature at an elevation (STE)
▪ Monthly mean of average daily temperature for the hottest month of the year (Ta)
▪ Monthly mean of the maximum daily temperature for the same month (Tm)

Where, h – height above MSL in m

r – rate of change of temp. with height or depth above MSL ( 0.0065 ⁰C/m)

CEC-3170: TRANSPORTATION: Traffic & Airport Engineering

AIRPORT ENVIRONMENT: TEMPERATURE

❑ Effect of Temperature
▪ Air density reduces as the elevation increases which in turn reduces the
lift on the wings of the aircraft.
▪ Thus reduces drag on aircraft while landing or requires longer distance
for producing necessary lift for the aircraft to fly.
▪ Increases basic runway length, the increase being 1% for every 1ºC rise
in airport reference temperature above the standard temperature at that
elevation. (as per ICAO, International Civil Aviation Organization)

CEC-3170: TRANSPORTATION: Traffic & Airport Engineering

AIRPORT ENVIRONMENT: SURFACE WIND
Surface Wind:
❑ Head Wind:
▪ Provides breaking during landing.
▪ Greater lift during take-off.
▪ Reduces runway length
❑ Tail Wind:
▪ Pushes the aircraft in forward direction
▪ Generation of lift is difficult
▪ Increases runway length by a large value
❑ Cross Wind:
▪ It has two components, one along the aircraft and other transverse to the aircraft
▪ The component along the aircraft may act as head wind or as tail wind
▪ The component transverse to the aircraft produces sway in the movement of the
aircraft. If it is very high then it may cause eccentric landing or take-off (away
from air path) CEC-3170: TRANSPORTATION: Traffic & Airport Engineering
AIRPORT ENVIRONMENT: ALTITUDE

❑ Altitude:
▪ Affects air density, atmospheric pressure and temperature.
▪ The reduction in air density or atmospheric pressure with height above
MSL affects the drag and lift forces and subsequent requirement of length
of runway.
▪ Requires longer runway length, increase being 7% per 300m altitude
above MSL.

CEC-3170: TRANSPORTATION: Traffic & Airport Engineering

AIRPORT ENVIRONMENT: GRADIENT
❑ Runway Gradient:
▪ Runway gradients are of two types:
✓ Longitudinal gradient:
➢ Quick disposal of water from the pavement surface.
➢ If the gradient is steep it may cause pre-mature lift-off or may induce
structural defects.
➢ It will cause more consumption of energy, therefore, will require longer length
of runway to attain the desired ground speed.
✓ Transverse gradient:
➢ Average gradient, computed based on difference in maximum and minimum
elevation along the runway and divided by the total length of runway.
➢ Runway length to be increased at a rate of 20% for every 1% of the effective
gradient. (FAA)
CEC-3170: TRANSPORTATION: Traffic & Airport Engineering
CORRECTIONS TO BASIC RUNWAY LENGTH

❑ Elevation correction
❑ Temperature correction and
❑ Gradient correction

These corrections have to be applied in the same sequence as listed above

CEC-3170: TRANSPORTATION: Traffic & Airport Engineering

CORRECTIONS TO BASIC RUNWAY LENGTH

CEC-3170: TRANSPORTATION: Traffic & Airport Engineering

PROCEDURE TO CALCULATE RUNWAY LENGTH

❑ Elevation correction
▪ Find the required basic field runway length under standard conditions ‘LB’
▪ Calculate elevation correction rate ‘Le’ and apply it to ‘LB’
▪ Add this value to ‘LB’. Lets denote it as ‘LE’.

CEC-3170: TRANSPORTATION: Traffic & Airport Engineering

PROCEDURE TO CALCULATE RUNWAY LENGTH

❑ Temperature Correction
▪ Calculate airport reference temperature (ART)
▪ Calculate standard temperature at the given elevation (ST).
▪ Calculate temperature correction rate ‘Lt’ and apply it to ‘LE’.
▪ Add this value to ‘LE’. Lets denote this corrected length as ‘LT’

CEC-3170: TRANSPORTATION: Traffic & Airport Engineering

PROCEDURE TO CALCULATE RUNWAY LENGTH

➢ Check on combined correction for temperature and elevation

▪ Calculate percentage increase in length after the two corrections with respect to
‘LB’. i.e. (Lt + Le).
▪ It is OK if less than and equal to 35%.
▪ If it is more than 35% then model testing has to be carried out.

CEC-3170: TRANSPORTATION: Traffic & Airport Engineering

PROCEDURE TO CALCULATE RUNWAY LENGTH

❑ Gradient Correction
▪ Calculate effective gradient, if not given.

▪ Calculate gradient correction rate ‘Lg’ and apply it to ‘LT’.

▪ Add this value to ‘LT’

▪ This is the final corrected length of runway.

CEC-3170: TRANSPORTATION: Traffic & Airport Engineering

PROBLEM 1
The data below refers to the daily temperature for the hottest month of the year for a given airport site.
Determine the airport reference temperature.

CEC-3170: TRANSPORTATION: Traffic & Airport Engineering

PROBLEM 2
The length of runway under standard conditions is 1620m. The airport
site has an elevation of 270m. Its reference temperature is 32.94°C. If
the runway is to be constructed with an effective gradient of 0.20
percent, determine the corrected runway length.

CEC-3170: TRANSPORTATION: Traffic & Airport Engineering

PROBLEM 2
The length of runway under standard conditions is 1620m. The airport
site has an elevation of 270m. Its reference temperature is 32.94°C. If
the runway is to be constructed with an effective gradient of 0.20
percent, determine the corrected runway length.

CEC-3170: TRANSPORTATION: Traffic & Airport Engineering

PROBLEM 2

CEC-3170: TRANSPORTATION: Traffic & Airport Engineering

PROBLEM 3

CEC-3170: TRANSPORTATION: Traffic & Airport Engineering

PROBLEM 4

CEC-3170: TRANSPORTATION: Traffic & Airport Engineering

PROBLEM 4

CEC-3170: TRANSPORTATION: Traffic & Airport Engineering

PROBLEM 4

CEC-3170: TRANSPORTATION: Traffic & Airport Engineering

PROBLEM 4

CEC-3170: TRANSPORTATION: Traffic & Airport Engineering

PROBLEM 5
The following data refers to the proposed longitudinal section of
runway.

If one metric chain is of 20m length,

determine the effective gradient of
runway.
CEC-3170: TRANSPORTATION: Traffic & Airport Engineering
GEOMETRIC DESIGN

❑Length of runway
❑Width of runway strip
❑Sight Distance
❑Longitudinal and Effective Gradient
❑Rate of Change of Longitudinal Gradient
❑Transverse Gradient
❑Safety Area
*Codal provisions for runway geometry, are given by International Civil Aviation Organization (ICAO)
CEC-3170: TRANSPORTATION: Traffic & Airport Engineering
AIRPORT CAPACITY

Airport capacity refers to the maximum number of aircraft operations

(landings and takeoffs) an airport can handle safely and efficiently within
a given time period. It's a crucial factor in ensuring smooth and reliable
air travel. The exact capacity depends on various factors, including the
number and configuration of runways, airspace constraints, weather
conditions, and aircraft mix.

CEC-3170: TRANSPORTATION: Traffic & Airport Engineering

AIRCRAFT PARKING CONFIGURATION

CEC-3170: TRANSPORTATION: Traffic & Airport Engineering

AIRCRAFT PARKING SYSTEM

❑ Frontal System
❑ Open Apron system
❑ Finger System
❑ Satellite System

CEC-3170: TRANSPORTATION: Traffic & Airport Engineering

WIND AND LANDING DIRECTION INDICATORS

❑ It is a visual aid for navigation.

❑ It tells the direction of wind.
❑ It helps ATCO (air traffic control officer) to choose
runway direction for take off and landing.
❑ It helps in determining the approx. wind speed.
❑ It should be in the form of a truncated cone made
off fabric and should have length not less than 3.6
m and diameter at larger end not less than 0.9 m.
❑ It should be understandable from a height of 300 m.
❑ Colour combination: red-white, black-white,
orange-white.
❑ It should be marked by circular band of 15 m in
diameter and 1.2 m wide.
❑ Height from ground should be such that it does not
penetrate in OFZ (obstacleCEC-3170:
free zone).
TRANSPORTATION: Traffic & Airport Engineering