A Comparative Analysis on Design of Rigid Runway Pavements

A COMPARATIVE STUDY ON THE DESIGN OF
RIGID RUNWAY PAVEMENTS
A REPORT ON MINOR PROJECT
A Dissertation Submitted to
Rajiv Gandhi Pradyogiki Vishwavidyalaya, Bhopal
for partial fulfillment of degree
Bachelor of Engineering
[ Civil Engineering ]
Supervised By Submitted By Enrollment no.
Mr. H.S. Goliya Nandini Fatrod 0801IT151044
Associate Professor Sarika Dodwe 0801CE151087
CE-AMD Anil Randa 0801CE151019
SGSITS, INDORE Shobhit Bajpai 0801CE151093
Yash Gang 0801CE151117
DEPARTMENT OF CIVIL ENGINEERING AND APPLIED MECHANICS
SHRI G.S. INSTITUTE OF TECHNOLOGY AND SCIENCE, INDORE

A Govt. Aided Autonomous Institute
Affiliated to R.G.P.V., Bhopal
RECOMMENDATION
We are pleased to recommend that the discretion of project entitled A
COMPARATIVE STUDY ON THE DESIGN OF RIGID RUNWAY
PAVEMENTS submitted by Nandini Fatrod, Sarika Dodwe, Anil Randa,
Shobhit Bajpai And Yash Gang, may be accepted in partial fulfillment of
degree Bachelor of Engineering [ Civil Engineering ] of Rajiv Gandhi
Pradyogiki Vishwavidyalaya, Bhopal during the year 2018-2019.
Mr. H.S. Goliya Dr D.J. Killedar
Associate Professor Professor and Head
CE-AMD CE-AMD
SGSITS, Indore SGSITS, Indore

A Govt. Aided Autonomous Institute
Affiliated to R.G.P.V., Bhopal
CERTIFICATE
This is to certify that the dissertation entitled A Comparative Study on Design
of Rigid Runway Pavements is submitted by Nandini Fatrod, Sarika Dodwe,
Anil Randa, Shobhit Bajpai And Yash Gang is accepted in partial fulfillment
of degree Bachelor of Engineering [ Civil Engineering ] of Rajiv Gandhi
Pradyogiki Vishwavidyalaya, Bhopal during the year 2018-2019.
Internal Examiner External examiner
Date Date

DECLARATION
We, Nandini Fatrod, Sarika Dodwe, Anil Randa, Shobhit Bajpai And Yash
Gang, the students of, B.E. Civil Engineering declare, the dissertation A
Comparative Study on Design of Rigid Runway Pavements is our own work
concerned under the supervision of Mr. H.S. Goliya Associate Professor Civil
Engineering and Applied Mechanics Department SGSITS, Indore. (M.P.)
We further declare that to do the best of our knowledge that this work does not
contain any part of any work submitted before for any kind of project work.
Name Enrollment Number Date Signature
……………………………... ……………………………... ……………… ……………………
……………………………... ……………………………... ……………… ……………………
……………………………... ……………………………... ……………… ……………………
……………………………... ……………………………... ……………… ……………………
……………………………... ……………………………... ……………… ……………………

Acknowledgement
We would like to express our profound gratitude to our project mentor Mr. H.S. Goliya
Associate Professor Civil Engineering and Applied Mechanics Department for his energy,
generous guidance, vision, brilliance, commitment and the friendship that we received during
our project work. It would not have been possible to complete this project without his
insightful advice, leadership, dedication and support.
We would like to express our gratitude towards Mr. Tarun for his support and guiding us in
this project.
We would like to give our warm expression of thanks to all the project members for their
support throughout the project.
Nandini Fatrod
Sarika Dodwe
Anil Randa
Shobhit Bajpai
Yash Gang

Abstract
The growth of air transportation is one of the most remarkable technological developments
of last century.
As we see the recent change in the mindset of people, we can say that people are now
becoming aware of various simple and faster ways to complete their tasks. As far as
development is considered, one of the key factors that come in play is the transportation of
cargo and travel.
India being the developing country with large population inbound and with large tourism
network. It offers tourist from all around the world through flights. India is expected to
welcome 217 million domestic with 76 million international passengers by 2020. There is a
need for crowd handling airport facility with the high efficient airport in India. India can
emerge as third highest aviation by 2020.
Not only in development but also in speed and time management travelling by air has
increased exponentially and is increasing day by day.
Keeping above points in mind, runways are designed for takeoff and landing operations.
They are designed for a longer life then our normal rigid pavements. As the load
characteristics changes there are different methods to design the runway.
The two types of runway pavements generally used are rigid and flexible pavements. Flexible
pavements and rigid pavements transfer the loads in different manner, but to predict the life
of runway by flexible pavement is a bit tougher task since it behaves as a grained system
while rigid pavements behavior is simple.
Also the life of flexible pavement is altered by variations in the load other than designed load
if it is supposed to occur so being in safer side and also heading towards safer side for design
and predicting the age of runway and to study the behavior of the pavement rigid pavements
are preferred.
Keywords: Airfield pavement, Airport, Design, Life, Load, Design and Runway.

Contents
 Recommendation I.
 Certificate II.
 Declaration III.
 Acknowledgement IV.
 Abstract V.
 Content VI.
 List of tables VII.
 List of figures VIII.
 List of abbreviation IX.
 Introduction 1
 Airport 1
 Aircraft Load considerations 5
 Pavement 7
 Runway 8
 Rigid and Flexible Pavements 16
 Rigid Pavement 16
 Flexible Pavement 17
 Comparison between Flexible and Rigid Pavement 18
 Pavement Analysis 22
 Design by Lcn and Lcg method 24
 Design by Pca method 30
 Design by FAARfield 34
 Results 42
 Conclusion 44
 References X

List of Figures
Figure 1 Section Of Runway
Figure 4 Runway Marking
Figure 5 Rigid Pavement
Figure 6 Flexible Pavement
Figure 7 Comparision Flex. And Rigid
Figure 8 Lcn And Lcg Charts
Figure 9 Relation Between Tyre Pressure And Eswl
Figure 10 Design Curve For Lcn And Lcg Methods
Figure 11 Relation Beteeen Eswl And Contact Area
Figure 12 Design Chart For Pca By Eswl Loads
Figure 13 Design Chart For Pca By Dwl Loads
Figure 14 Cdf Variation Curve
Figure 15 Design Table For Pavement
Figure 16 Design Pavement

List of Tables
Table 1 Runway Marking
Table 2 Design By Lcn Method
Table 3 Design By Pca For Eswl
Table 4 Design By Pca For Dwl
Table 5 Allowable Modulus Values And Poisson’s Ratios
Table 6 Minimum Layer Thickness For Rigid Pavement Structures
Table 7 Airplane Information
Table 8 Airplane Cdf Contribution
Table 9 Pavement Design By Faarfield

List of Abbreviations
CDF Cumulative Damage Factor
LCN Load Classification Number
PCA Portland Cement Association
ESWL Equivalent Single Wheel Load
DWL Dual Wheel Load
K Modulus Of Subgrade Reaction
LCG Load Classification Group
CBR California Bearing Ratio
FOS Factor Of Safety
CDF Cumulative Damage Factor

References
1. Airport Planning and Design by S.K. Khanna, M.G. Arora, S.S. Jain. Nem Chand
Brothers; 6th edition (1999)
2. Wikipedia article on Runway
https://en.wikipedia.org/wiki/Runway
Dated- 21/08/2018
3. Introduction to airport and load characteristics “
https://nptel.ac.in/courses/105104098/7”
Dated- 31/12/2009
4. Faarfield design theory basics
https://www.faa.gov/airports/engineering/pavement_design/
Dated-11/10/2016
5. Design standards specified by faa
https://www.faa.gov/airports/engineering/designstandards/
Dated-11/10/2016
6. Software used in design by Faarfield method
http://www.faa.gov/airports/engineering/design_software/
Date-15/09/2018 faarfield version (version 3.3.2.FAA.2.3).
7. IOSR Journal of Mechanical and Civil Engineering (IOSR-JMCE)
http://www.windroseplot.com/publications/B011231027.pdf
e-ISSN: 2278-1684,p-ISSN: 2320-334X, Volume 11, Issue 2 Ver. III (Mar- Apr. 2014),
PP 10-27

A Comparative Study on Design of Rigid Runway Pavement 2018
CE-AMD SGSITS, INDORE 1
CHAPTER 1
INTRODUCTION
The two types of runway pavements generally used are rigid and flexible pavements. Flexible
pavements and rigid pavements transfer the loads in different manner, but to predict the life
of runway by flexible pavement is a bit tougher task since it behaves as a grained system
while rigid pavements behavior is simple.
Also the life of flexible pavement is altered by variations in the load other than designed load
if it is supposed to occur so being in safer side and also heading towards safer side for design
and predicting the age of runway and to study the behavior of the pavement rigid pavements
are preferred.
The project is to make a comparative study on the methods by which pavements for the
runways are designed and to comment on the most suited method to design a pavement.
Looking at the designing part, there are some empherical methods, graphical methods and
some semi empherical methods.
The project overall shows how stress and contact area vary and the thickness.
AIRPORT
An airport is an aerodrome with extended facilities, mostly for commercial air
transport. Airports often have facilities to store and maintain aircraft, and a control tower. An
airport consists of a landing area, which comprises an aerially accessible open space
including at least one operationally active surface such as a runway for a plane to take off,
a helipad, and often includes adjacent utility buildings such as control towers, hangars
and terminals. Larger airports may have fixed-base operator services, airport aprons, taxiway
bridges, and air traffic control centers, passenger facilities such as restaurants and lounges,
and emergency services. An airport for use by seaplanes and amphibious aircraft is called
a seaplane base. Such a base typically includes a stretch of open water for take offs
and landings, and seaplane docks for tying-up. An international airport has additional
facilities for customs and passport control as well for incorporating all of the aforementioned
elements. Such airports rank among the most complex and largest of all built typologies
with 15 of the top 50 buildings by floor area being airport terminals.
Components of Airport
There are various components of an airport which are structures. The planning
and designing of these Airport components are carried out by civil and structural engineers.
 Runway
 Taxiway
 Apron

 Terminal building
 Control tower
 Hanger
 Parking
1. Runway
Runway is a paved land strip on which landing and takeoff operations of aircrafts takes
place. It is in leveled position without any obstructions on it. Special markings are made on
the runway to differ it from the normal roadways. Similarly, after sunset, specially provided
lightings are helped the aircrafts for safe landing. Many factors are considered for design of
runway. The direction of runway should be in the direction of wind. Sometimes cross winds
may happen, so, for safety considerations second runway should be laid normal to the main
runway. The number of runways for an airport is depends upon the traffic. If the traffic is
more than 30 movements per hour, then it is necessary to provide another runway. Runway
can be laid using bitumen or concrete. Bitumen is economic but concrete runways have long
span and requires less maintenance cost. The width of runway is dependent of maximum size
of aircrafts utilizing it. The length of runway is decided from different considerations like
elevation of land, temperature, take off height, gradients etc.
2. Taxiway
Taxiway is path which connects each end of the runway with terminal area, apron, hanger
etc. These are laid with asphalt or concrete like runways. In modern airports, taxiways are
laid at an angle of 30 degree to the runway so that aircrafts can use it to change from one
runway to other easily. The turning radius at taxiway and runway meets should be more than
1.5 times of width of taxiway.
3. Apron
Apron is a place which is used as parking place for aircrafts. It is also used for loading
and unloading of aircrafts. Apron is generally paved and is located in front of terminal
building or adjacent to hangers. The size of area to be allotted for apron and design of apron
is generally governed by the number of aircrafts expected in the airport. The aircraft
characteristics also considered while design. Proper drainage facilities should be provided
with suitable slope of pavement. Sufficient clearances must be provided for aircrafts to
bypass each other.
4. Terminal Building
Terminal building is a place where airport administration facilities take place. In this
building, pre-journey and post journey checking’s of passengers takes place. Lounges, cafes
etc. are provided for the passengers. Passengers can directly enter the plane from terminal
buildings through sky bridge, walkways etc. Similarly, the passengers from plane also
directly enter into the terminal building.
5. Control Tower
The control tower is a place where aircrafts under a particular zone is controlled whether
they are in land or in air. The observation is done by the controller through radars and

information is carried through radio. The controller from the control tower observes all the
aircrafts with in that zone and informs pilots about their airport traffic, landing routes,
visibility, wind speeds, runway details, etc. based on which the pilot decides and attempts
safe landing. So, control tower is like nerve system of an airport.
6. Hanger
Hanger is a place where repairing and servicing of aircrafts is done. Taxiway connects the
hanger with runway so, when a repair needed for an aircraft it can be moved to hanger easily.
It is constructed in the form of large shed using steel trusses and frames. Large area should be
provided for Hanger for comfortable movement of aircrafts.
7. Parking
This is a place provided for parking the vehicles of airport staff or passengers which is
outside the terminal building or sometimes under the ground of terminal building.
AIRCRAFT CHARACTERISTICS
Aircraft and airport are dependent on each other in providing a service for the passenger in
conventional air transport system. In the past, the system evolved largely with separate
planning of the airport, the route structuring and the aircraft technology. With the
advancement in technology, the major factor in the growth of the mode, have been quickly
utilized by the airlines in expanding their route structures. Advancement in engine and
airframe technology have also been found significant in the reduction of real cost of air travel
and at the same time have led to improvements in system performances. This has resulted in a
natural tendency for the airports to accommodate any changes in aircraft design and
performance that could maintain the trend to lower the aircraft direct operating cost (DOC)
Aircraft characteristics are of prime importance to the airport planner and designer. The
following characteristics
 Type of propulsion
 Size of aircraft
 Minimum turning radius
 Minimum circling radius
 Speed of aircraft
 Capacity of aircraft
 Aircraft weight and wheel configuration
 Jet blast
 Fuel spillage
 Noise
1. Types of Propulsion
The size of aircraft, its circling radius, speed characteristic, weight carrying capacity,
noise nuisance etc. depend upon the type of propulsion of the aircraft. The performance
characteristics of aircrafts, which determine the basic runway length, also depend upon the

type of propulsion. That heat nuisance due to exhaust gases is a characteristic of turbo jet and
turbo prop engines.
2. Size of Aircraft
The sizes of aircraft involves following important dimensions: The wing span decides the
width of taxiway, separation clearance between two parallel traffic ways, size of aprons and
hangars, width of hangar gate etc. The length of aircraft decides the widening of taxiways on
curves width of exit taxiway, sizes of aprons and hangars etc. The height of aircraft, also
called as empennage height, decides the height of hangar gate and miscellaneous installations
inside the hangar. The gear tread and the wheel base affect the minimum turning radius of
the aircraft.
3. Minimum Turning Radius
In order to decide the radius of taxiways, the position of aircrafts in loading aprons and
hangars and to establish the path of the movement of aircraft, it is very essential to study the
geometry of the turning movement of aircrafts. The turning radius of an aircraft is illustrated
in the Figure. To determine the minimum tuning radius, a line is drawn through the axis of
the nose gear when it is at its maximum angle of rotation the point, where this line intersects
another line drawn through the axis of the two main, gears, and is called the centre of
rotation.
4. Minimum Circling Radius
There is certain minimum radius with which the aircraft can take turn in space. This
radius depends upon the type of aircraft air traffic volume and weather conditions. The radii
recommended for different types of aircrafts are as follows
 Small general aviation aircrafts under UFR conditions, 1.6 km (1 mile)
 Bigger aircrafts, say two piston engine under VFR conditions = 32 km (2 mile)
 Piston engine aircrafts under IFR conditions. = 13 kin (8 miles)
 Jet engine aircrafts under IFR conditions= 80 km (50 miles)
The two nearby airports should be separated from each other by an adequate distance so
that the aircrafts simultaneously landing on them do not interfere with each other. If the
desirable spacing between the airports cannot he provided, the landing and takeoff aircrafts in
each airport will have to be timed so as to avoid collision.
5. Speed of Aircrafts
The speed of aircraft can be defined in two ways viz. ground speed and air peed Cruising
speed is with respect to the ground when the aircraft is flying in air at its maximum speed.
Air speed is the steed of aircraft relative to the wind.
6. Aircraft Capacity
The number of passengers, baggage, cargo and fuel that can be accommodated in the
aircrafts depends upon the capacity of aircraft. The capacity of aircraft using an airport has an
important effect on the capacity of runway systems as well as that of the passenger
processing terminal facilities.

7. Weight of Aircraft & Wheel Configuration
Weight of the aircraft directly influence the length of the runway as well as the structural
requirements i.e. the thickness of the runway, taxiway, apron & hangars. It depends not only
on the weight of the passenger baggage, cargo and fuel it is carrying and its structural weight,
but also on the fuel which is continuously decreasing during the course of the flight.
8. Jet Blast
At relatively high velocities, the aircrafts eject hot exhaust gases; the velocity of jet blast
may be as high as 300 kmph. This high velocity cause inconvenience to the passengers
travelling in the aircraft. Several types of jet blast deflector are available to serve as an
effective measure for diverting the smoke ejected by the engine to avoid the inconvenience to
the passengers. Since, the bituminous (flexible) pavements are affected by the jet bust,
therefore, it is desirable to provide cement concrete pavement at least at the touch down
portion to resist the effect of the blast in preference to the bituminous pavements. The effect
of the jet blast should also be considered for determining the position, size and location of
gates.
9. Fuel Spillage
At loading aprons and hangars, it is difficult to avoid spillage completely, but effort
should be made to bring it within minimum limit. The bituminous (flexible pavements are
seriously affected by the fuel spillage and therefore, it is essential that the areas of bituminous
pavements under the fuelling inlets, the engines and the main landing gears are kept under
constant supervision by the airport authorities.
10. Noise
Noise generated by aircraft creates problems in making decisions on layout and capacity.
The correct assessment of future noise patterns to minimize the effect of surrounding
communities is essential to the optimal layout of the runways. The FAA noise regulations
came into force in 1969 for jet-powered aircraft with bypass ratios greater than 2. In 1973,
they were modified to apply to all aircraft manufactured after that date.
Aircraft Load Considerations
Pavements should be designed for the maximum anticipated takeoff weights of the
airplanes in the fleet regularly operating on the section of pavement being designed. The
design procedure generally assumes 95 percent of the gross weight is carried by the main
landing gears and 5 percent is carried by the nose gear. FAARFIELD provides manufacturer-
recommended gross operating weights and load distribution, for many civil and military
airplanes. Using the maximum anticipated takeoff weight provides a conservative design
allowing for changes in operational use and traffic, at airports where traffic regularly operates
at less than maximum load. Landing Gear Type and Geometry configuration dictate how
airplane weight is distributed to a pavement and how the pavement responds to airplane
loadings.

Tire Pressure
Tire pressure varies depending on gear configuration, gross weight, and tire size. In
FAARFIELD, the tire pressure is linked to the gross weight. An increase in gross weight
causes a proportional increase in tire pressure, such that the tire contact area is maintained
constant. Tire pressure has a negligible impact on rigid pavement design.
Aircraft Traffic Volume
Forecasts of annual departures by airplane type are needed for pavement design. In
general, pavements should be designed to accommodate regularly using aircraft, where
regular use is defined as at least 250 annual departures (500 operations).
Departure Traffic
Airfield pavements are generally designed considering only aircraft departures. This
is because typically aircraft depart at a heavier weight than they arrive. If the aircraft arrive
and depart at essentially the same weight, then the number of departures used for pavement
design should be adjusted to reflect the number of times the pavement is loaded with each
aircraft operation in the FAARFIELD pavement analysis.
Total Departures over Design Life
FAARFIELD evaluates the total number of departures over the design life period. For
example, FAARFIELD considers 250 annual departures for a 20-year design life to be 5,000
total departures. Similarly, FAARFIELD considers 225 annual departures at a 1% annual
growth rate to be 4,950 total departures.
Airplane Traffic Mix
Nearly any traffic mix can be developed from the airplanes in the program library.
The actual anticipated traffic mix must be used for the design analysis. Attempts to substitute
equivalent aircraft for actual aircraft can lead to erroneous results.
Total Cumulative Damage
FAARFIELD analyzes the damage to the pavement for each airplane and determines
a final thickness for the total cumulative damage of all aircraft in the evaluation.
FAARFIELD calculates the damaging effects of each airplane in the traffic mix based upon
its gear spacing, load, and location of gear relative to the pavement centerline. When the
cumulative damage factor (CDF) sums to a value of 1.0, the structural design conditions have
been satisfied. Cumulative damage factor (CDF) is the amount of the structural fatigue life of
a pavement that has been used up. It is expressed as the ratio of applied load repetitions to
allowable load repetitions to failure, or, for one airplane and constant annual departures

 When CDF = 1, the pavement will have used up all of its fatigue life.
 When CDF < 1, the pavement will have some life remaining, and the value of CDF
will give the fraction of the life used.
 When CDF > 1, all of the fatigue life will have been used up and the pavement will
have failed. Multiple airplane types are accounted for by using Miner's Rule:
 CDF = CDF1 + CDF2 + ... CDFN
Where CDFI is the CDF for each airplane type in the mix and N is the number of airplane
types in the mix.
Pass-to-Coverage Ratio: As an airplane moves along a taxiway or runway, it may take
several trips or passes along the pavement for a specific point on the pavement to receive a
full-load application. The ratio of the number of passes required to apply one full load
application to a unit area of the pavement is expressed by the pass-to-coverage (P/C) ratio. It
is easy to observe the number of passes an airplane may make on a given pavement, but the
number of coverage is mathematically derived internally in FAARFIELD. For rigid
pavements, coverage area a measure of repetitions of the maximum stress occurring at the
bottom of the PCC layer.
Annual Departures
When arrival and departure weights are not significantly different or when the
airplane must travel along the pavement more than once, it may be appropriate to adjust the
number of annual departures used for thickness design to recognize that each departure
results in multiple pavement loadings.
PAVEMENT
The choice of material used to construct the runway depends on the use and the local
ground conditions. Runway pavement surface is prepared and maintained to maximize
friction for wheel braking. To minimize hydroplaning following heavy rain, the pavement
surface is usually grooved so that the surface water film flows into the grooves and the peaks
between grooves will still be in contact with the aircraft tires. The dynamic response of the
vehicles using the landing area because airport pavement construction is so expensive,
manufacturers aim to minimize aircraft stresses on the pavement. Manufacturers of the larger
planes design landing gear so that the weight of the plane is supported on larger and more
numerous tires. Attention is also paid to the characteristics of the landing gear itself, so that
adverse effects on the pavement are minimized. Sometimes it is possible to reinforce a
pavement for higher loading by applying an overlay of asphaltic concrete or Portland cement
concrete that is bonded to the original slab. Post-tensioning concrete has been developed for
the runway surface. This permits the use of thinner pavements and should result in longer
concrete pavement life.

RUNWAY
Runways are named by a number between 01 and 36, which is generally the magnetic
azimuth of the runway's heading in decadegrees. This heading differs from true north by the
local magnetic declination. A runway numbered 09 points east (90°), runway 18 is south
(180°), runway 27 points west (270°) and runway 36 points to the north (360° rather than
0°).A runway can normally be used in both directions, and is named for each direction
separately: e.g., "runway 33" in one direction is "runway 15" when used in the other. The two
numbers usually differ by 18 (= 180°).Runway designations change over time because the
magnetic poles slowly drift on the Earth's surface and the magnetic bearing will change.
Depending on the airport location and how much drift takes place, it may be necessary over
time to change the runway designation. As runways are designated with headings rounded to
the nearest 10 degrees, this will affect some runways more than others.
The runway is a major element of the airport. It is clearly defined area of an airport
prepared for landing and/or take off of aircraft. Runways and taxiways should be so planned
in relations to other major operating elements such as terminal building, cargo areas, aprons
air traffic services and parking etc. to provide an airport configuration offering the maximum
overall efficiency. Runways are normally identified by the principal elements.
Runway location and orientation are of the utmost importance to aviation safety,
comfort and convenience of operation, environment impacts, and the overall efficiency and
economics of the airport. In establishing a new runway layout and/or evaluating existing
layouts for improvements where runways are added and/or existing runways are extended,
the factor influencing runway location and orientation should be considered. The weight and
degree of concern to be given to each factor are in part dependent on the airplane types
expected to utilize each runway, the meteorological conditions to be accommodated, the
surrounding environment and the volume of air traffic expected to be generated on each
runway. Following factors should be considered in location and orienting new runways
and/or establishing which end of existing runways should be extended.
 Location of neighboring airports.
 Obstruction and topography.
 Built up areas and noise.
 Air traffic control technique.
 Wind direction and visibility condition.
 Capacity (type and amount of traffic).
Types of Runways
Visual runways are used at small airstrips and are usually just a strip of grass, gravel,
ice, asphalt, or concrete. Although there are usually no markings on a visual runway, they
may have threshold markings, designators, and centerlines. Additionally, they do not provide
an instrument-based landing procedure; pilots must be able to see the runway to use it. Also,
radio communication may not be available and pilots must be self-reliant.

Non-precision instrument runways are often used at small- to medium-size airports.
These runways, depending on the surface, may be marked with threshold markings,
designators, centerlines, and sometimes a 1,000 ft. (305 m) mark (known as an aiming point,
sometimes installed at 1,500 ft. (457 m)). They provide horizontal position guidance to planes
on instrument approach via Non-directional beacon, VHF Omni directional range, Global
Positioning System, etc.
Precision instrument runways, which are found at medium- and large-size airports,
consist of a blast pad/stop-way (optional, for airports handling jets), threshold, designator,
centerline, aiming point, and 500 ft. (152 m), 1,000 ft. (305 m)/1,500 ft. (457 m), 2,000 ft.
(610 m), 2,500 ft. (762 m), and 3,000 ft. (914 m) touchdown zone marks. Precision runways
provide both horizontal and vertical guidance for instrument approaches.
There are different runway patterns are available and they are
 Single runway
 Two runways
 Hexagonal runway
 45-degree runway
 60-degree runway
 60-degree parallel runway
 Single Runway
Single runway is the most common form. It is enough for light traffic airports or for
occasional usages. This runway is laid in the direction of wind in that particular area.
Two runways contain two runways which are laid in different directions by
considering cross winds or wind conditions in that particular area. The runways may be laid
in the form of L shape or T shape or X shape.
Hexagonal Runway is the modern pattern of system of runway laying. In which the
takeoff and landing movements of aircrafts can be permitted at any given time without any
interference. This is most suitable for heavy traffic airports or busiest airports.
45 Degree Runway is opted when the wind coverage for same airfield capacity is
greater. This is also termed as four-way runway.
60 Degree Runway is opted when the wind in that area is prevailing in many
directions, so, it is difficult to decide the direction in which runway is to be laid. In that case,
60-degree runway is opted which looks like triangular arrangement of runways.
60 Degree Parallel Runway is the extension of 60-degree runway, which is opted
when the wind coverage is greater in other two directions then it is obvious that the third
runway is to be chosen.

But if the air traffic is more, then it is difficult to control the operations. Hence,
another runway is required parallel to the using one. For that purpose, 60-degree parallel
runway is suitable.
1) Runway Length
A runway of at least 1,829 m in length is usually adequate for aircraft weights below
approximately 90,718 kg. Larger aircraft including wide bodies will usually require at least
2,438 m at sea level and somewhat more at higher altitude airports. International wide body
flights, which carry substantial amounts of fuel and are therefore heavier, may also have
landing requirements of 3,048 m or more and takeoff requirements of 3,962 m. The Boeing
747 is considered to have the longest takeoff distance of the more common aircraft types and
has set the standard for runway lengths of larger international airports.
At sea level, 3,048 m can be considered an adequate length to land virtually any aircraft. An
aircraft taking off at a higher altitude must do so at reduced weight due to decreased density
of air at higher altitudes, which reduces engine power. An aircraft must also take off at a
reduced weight in hotter or more humid conditions. Most commercial aircraft carry
manufacturer's tables showing the adjustments required for a given temperature.
2) Orientation of the Runway
Wind is a key factor influencing runway orientation and the number of runways.
Ideally, a runway should be aligned with the prevailing wind. Wind conditions affect all
aircraft in varying degrees. Generally, the smaller the aircraft, the more it is affected by wind,
particularly crosswind components which are often a contributing factor in small aircraft
accidents. The most common wind analysis procedure uses a windrose which is a scaled
graphical presentation of the wind information. Each segment of the windrose represents a
wind direction and speed grouping corresponding to the wind direction. The purpose of the
analysis is to determine the runway orientation which provides the greatest wind coverage
within the allowable crosswind component limits. In designing runway orientation, the most
desirable runway is one that has the largest wind coverage and minimum crosswind
components. The Wind Rose PRO software can be used for analyzing a long series of data
and calculating, for each possible runway direction, the wind coverage and the crosswind
components (maximum, average and median). The software can also be used to evaluate the
correct orientation of an existing runway. Moreover, since WindRose PRO allows date/time
filtering of the input data, it is possible to evaluate the wind coverage and the crosswind
components even for airports which work only in particular seasons (for example during
summer) or only during day time. The following steps illustrates the procedure followed
using the software tool:
 Step 1: Conversion meteorological reports in to a spreadsheet file.xls: Data collected
needs to be changed in to the specified units that the database file can take. This needs
to be done manually or by using Optical Character Recognition software (OCR).
Manual Conversion needs to be done with utmost care when it deals with the direction
of wind flow. Wind speed in Km/h should be converted in to m/s. Utilizing a

computer program would make this process easier. The whole plot is assumed to be
formed of segments of each 22.5 degree.
 Step 2: Loading of data, substitutions and assigning columns with directions and data.
 Step 3: Compute & Analyze the raw wind data to plot the wind rose. The value or the
degree of Runway Orientation can be obtained from the wind analysis report. The
design crosswind component chosen is 20knots and this should be converted in to m/s
and given as input. 1 knot = 0.51444 m/s
 Step 4: Calculation of crosswind component Runway design mode in the software is
enabled and the crosswind component calculation option is clicked. Mark the
crosswind calculation and enter the design crosswind component for the runway.
Based on the output generated and the analysis of the windrose diagram the following is
proposed:
The most advantageous runway orientation based on wind is the one which provides
the greatest wind coverage with the minimum crosswind components. Construction of two
runways may be necessary to achieve the desired 95.0 percent wind coverage.
Non-intersecting Runways which are divergent towards SOUTH-EAST and WEST of
SOUTH-WEST are proposed to ensure the 95.0% wind coverage and operation during most
of the time in all the seasons.
Divergent flight paths have the capacity of the order of operations from 80 to 110 per
hour under Visual Flight Rules (VFR) / (Clear weather) where cloud ceiling will be less than
300m.
Runway capacity is normally less under Instrument Flight Rules (IFR) conditions
where visibility is less than 4.8 Km (3 miles).
3) Declared Distances
Runway dimensions vary from as small as 245 m (804 ft.) long and 8 m (26 ft.) wide
in smaller general aviation airports, to 5,500 m (18,045 ft.) long and 80 m wide at large
international airports built to accommodate the largest jets.
Take-off Run Available (TORA) – The length of runway declared available and suitable for
the ground run of an airplane taking off.
Take-off Distance Available (TODA) – The length of the take-off run available plus the
length of the clearway, if clearway is provided. (The clearway length allowed must lie within
the aerodrome or airport boundary. According to the Federal Aviation Regulations and Joint
Aviation Requirements (JAR) TODA is the lesser of TORA plus clearway or 1.5 times
TORA).
Accelerate-Stop Distance Available (ASDA) – The length of the take-off run available plus
the length of the stop-way, if stop-way is provided.
Landing Distance Available (LDA) – The length of runway that is declared available and
suitable for the ground run of an airplane landing.

Emergency Distance Available (EDA) – LDA (or TORA) plus a stop-way.
4) Sections of a Runway
There exist standards for runway markings.
Figure 1
The runway thresholds are markings across the runway that denote the beginning and
end of the designated space for landing and take-off under non-emergency conditions.
The runway safety area is the cleared, smoothed and graded area around the paved
runway. It is kept free from any obstacles that might impede flight or ground roll of aircraft.
The runway is the surface from threshold to threshold, which typically features
threshold markings, numbers, and centre lines, but not overrun areas at both ends.
Blast pads, also known as overrun areas or stop-ways, are often constructed just
before the start of a runway where jet blast produced by large planes during the take-off roll
could otherwise erode the ground and eventually damage the runway. Overrun areas are also
constructed at the end of runways as emergency space to slowly stop planes that overrun the
runway on a landing gone wrong, or to slowly stop a plane on a rejected take-off or a take-off
gone wrong. Blast pads are often not as strong as the main paved surface of the runway and
are marked with yellow chevrons. Planes are not allowed to taxi, take off or land on blast
pads, except in an emergency.
Figure 2
Displaced thresholds may be used for taxiing, take-off, and landing rollout, but not for
touchdown. A displaced threshold often exists because obstacles just before the runway,
runway strength, or noise restrictions may make the beginning section of runway unsuitable
for landings. It is marked with white paint arrows that lead up to the beginning of the landing
portion of the runway.

Figure 3
4) Runway Safety
Types of runway safety incidents include:
 Runway excursion - An incident involving only a single aircraft, where it makes an
inappropriate exit from the runway (e.g. Thai Airways Flight 679).
 Runway overrun (also known as an overshoot) - A type of excursion where the
aircraft is unable to stop before the end of the runway.
 Runway incursion - An incident involving incorrect presence of a vehicle, person or
another aircraft on the runway.
 Runway confusion - An aircraft makes use of the wrong runway for landing or
takeoff.
5) Runway Markings
There are runway markings and signs on most large runways. Larger runways have a
distance remaining sign (black box with white numbers). This sign uses a single number to
indicate the remaining distance of the runway in thousands of feet. For example, a 7 will
indicate 7,000 ft. (2,134 m) remaining. The runway threshold is marked by a line of green
lights.
Figure 4
Table 1
1. Threshold Markings
Commence 6m from both sides Number of strips=16
Length of each strip=30m Width of strip=1.80m
Gap between each strip=1.80m
2. Aiming Point Markings
One rectangular strip on either side of centre line
Distance from threshold=300m Length of each strip=50m
Width of each strip=10m Gap between strips=20m

3. Touchdown Zone Markings
Number of strip on both side=4 Length of each strip=25m
Width of strip=3m Gap between each strip=1.5m
Lateral spacing between strips on either side= 20m
4. Centre Line Markings
Length of each strip=40m Gap between each strip=35m
Width of strip=0.5m
5. Runway Strip Markings
30m from centre line Width = 1m
6) Runway lightings:
Runway lighting is used at airports that allow night landings. Seen from the air,
runway lights form an outline of the runway. A runway may have some or all of the
following:
 Runway end identifier lights
 Runway end lights
 Runway edge lights
 Runway centerline lighting system
 Touchdown zone lights (TDZL)
 Taxiway centerline lead-off lights
 Taxiway centerline lead-on light
 Land and hold short lights
 Approach lighting system (ALS)
7) Control of Lighting System
Typically the lights are controlled by a control tower, a flight service station or
another designated authority. Some airports/airfields (particularly uncontrolled ones) are
equipped with pilot-controlled lighting, so that pilots can temporarily turn on the lights when
the relevant authority is not available. This avoids the need for automatic systems or staff to
turn the lights on at night or in other low visibility situations. This also avoids the cost of
having the lighting system on for extended periods. Smaller airports may not have lighted
runways or runway markings. Particularly at private airfields for light planes, there may be
nothing more than a windsock beside a landing strip.
1. Runway End Identification Lights (REIL): Unidirectional (facing approach
direction) or unidirectional pair of synchronized flashing lights installed at the runway
threshold, one on each side.
2. Runway end lights: Pair of four lights on each side of the runway on precision
instrument runways, these lights extends along the full width of the runway. These lights
show green when viewed by approaching aircraft and red when seen from the runway.

3. Runway edge lights: White elevated lights that run the length of the runway on
either side. On precision instrument runways, the edge-lighting becomes yellow in the last
2,000 ft (610 m) of the runway, or last third of the runway, whichever is less.
4. Runway Centerline Lighting System (RCLS): The lights embedded into the surface
of the runway at 50 ft (15 m) intervals along the runway centerline on some precision
instrument runways. White except the last 900 m (3,000 ft): alternate white and red for next
600 m (1,969 ft) and red for last 300 m (984 ft).
5. Touchdown Zone Lights (TDZL): The rows of white light bar (with three in each
row) at 30 or 60 m (98 or 200 ft) intervals on either side of the centerline for 900 m (3,000
ft).

CHAPTER 2
PAVEMENTS
RIGID PAVEMENT
A rigid pavement is constructed from cement concrete or reinforced concrete slabs.
Grouted concrete roads are in the category of semi-rigid pavements. The design of rigid
pavement is based on providing a structural cement concrete slab of sufficient strength to
resists the loads from traffic. The rigid pavement has rigidity and high modulus of elasticity
to distribute the load over a relatively wide area of soil. Minor variations in subgrade strength
have little influence on the structural capacity of a rigid pavement. In the design of a rigid
pavement, the flexural strength of concrete is the major factor and not the strength of
subgrade. Due to this property of pavement, when the subgrade deflects beneath the rigid
pavement, the concrete slab is able to bridge over the localized failures and areas of
inadequate support from subgrade because of slab action.
Figure 5

FLEXIBLE PAVEMENT
Flexible pavement can be defined as the one consisting of a mixture of asphaltic or
bituminous material and aggregates placed on a bed of compacted granular material of
appropriate quality in layers over the subgrade. Water bound macadam roads and stabilized
soil roads with or without asphaltic toppings are examples of flexible pavements.
The design of flexible pavement is based on the principle that for a load of any magnitude,
the intensity of a load diminishes as the load is transmitted downwards from the surface by
virtue of spreading over an increasingly larger area, by carrying it deep enough into the
ground through successive layers of granular material. Thus for flexible pavement, there can
be grading in the quality of materials used, the materials with high degree of strength is used
at or near the surface. Thus the strength of subgrade primarily influences the thickness of the
flexible pavement.
Figure 6

Rigid pavements over Flexible Pavement
Rigid pavements are typically distribute wheel loads over a wide area of the subgrade
as shown on the left side of the exhibit below and consist generally of cement concrete and
may be reinforced with steel. Other rigid pavement characteristics include:
 Design life typically 30+ year
 Lower maintenance costs
 High flexural strength
 Strength of road less dependent on strength of sub-grade
 Low ability to expand and contract with temperature and therefore need expansion
joints
 High ability to bridge imperfections in sub-grade
Flexible pavements typically distribute wheel loads to lower layers of the pavement
section as shown on the right side of the exhibit below and consist generally of bituminous
material. Other flexible pavement characteristics include:
 Design life typically 10 – 20 years
 Costs tied closely to price of oil
 Higher maintenance costs
 Low flexural strength
 Strength of road highly dependent on strength of sub-grade
 High ability to expand and contract with temperature and therefore do not need
expansion joints
 Low ability to bridge imperfections in sub-grade
Figure 7
Many developing countries are experiencing difficulties in maintaining road
networks. Road maintenance currently consumes a large proportion of the national and local
districts annual budget, yet the roads still deteriorate fast! The prospect of roads that are
comparatively maintenance-free should therefore be specially attractive to government
policy-planners, professionals in engineering and construction, and road users.

Experience from developed countries and some developing countries suggests that
roads constructed with cement-concrete surfaces require substantially minimal maintenance
throughout their design life. Developing economies, therefore, should consider seriously
building roads that last, so that other issues of development get attention too.
To analyze the comparative advantages and disadvantages of rigid to flexible
pavements, I believe experts should consider, among the 8Ms, Methods (of design,
construction and maintenance of the roads), Money (effective implementation of funds over
the projects), Materials, Manpower (locally available or cost-effective), and Mindset (the
ability of the policy-makers, engineers, consultants, to set their mind on the most economic
and cost-effective roads). This involves the ability to change our minds from believing that
the bituminous roads are always the better option while ignoring the best, that is, the rigid-
concrete roads which are initially expensive but cheaper in the long run because of low
maintenance costs over a 50-year lifespan.
Rigid pavements derive strength from the chemical reaction of cement and water
binding the aggregate together in a rigid mass. The materials for construction of a rigid
pavement surface are cement, sand, coarse aggregate, steel reinforcement (in some cases) and
water.
The design and construction of a rigid (concrete) pavement is therefore a lot similar to
the design and construction of a ground concrete slab in common construction of, say, a
building. One needs proper cement: water and matching amounts of aggregate and
reinforcement in the proper ratios. The common reinforcement is the mesh type, usually
known as BRC, to absorb tension stresses and curb cracking.
Everywhere in the world there are more people familiar with concrete than with
bitumen because concrete is used in most housing activities. Therefore a concrete road
pavement of good quality can be constructed by hand and only basic equipment for mixing
and transport. Technical supervision is of course necessary for quality assurance and
consistency.
Advantages of rigid over flexible pavements
In all issues of sustainability (that is, social, economic and environmental), concrete
scores better than asphalt as a road-building material. In terms of the materials, therefore,
rigid pavements have advantages over flexible pavements as concrete roads have longer
structural and service life because they do not require frequent repairs.
For a developing country, it also helps the economy to use local materials for
infrastructure development. In this regard, materials such as cement, aggregate and steel for
construction of concrete (rigid) pavements are available from local industries and nature.
Moreover, whereas the production process of asphalt produces gases which are harmful to the
environment, the making of concrete is environment-friendly. Furthermore, asphalt is
imported – a further needless stress on the economy.

The other advantage related to the longer life of rigid concrete pavements is the fact
that the oil that leaks from vehicles -- usually causing faster deterioration of the asphalt roads
-- does not affect the concrete-pavement roads. Concrete roads are rigid and do not deflect
under the wheels of loaded trucks. This means that vehicles use less fuel on the concrete
roads, an economic boon for the country if one tries to quantify it at national level.
Flexible pavements may have certain advantages. For example, on average, it takes
less time to lay a flexible (bituminous) pavement than a concrete one. Again, bituminous
roads present better skid-resistance and are therefore safer than the concrete ones.
Furthermore, the initial construction cost of a bituminous pavement is much lower than that
of the concrete one. However, lower cost does not mean economical in the medium or long-
term as most bituminous roads do not last longer than 15 years compared to concrete roads
which last far longer -- up to 50 years!
There’s a mindset that rigid pavements are expensive to build. Granted, they are more
costly to build in the short run than flexible ones, but are they not more cost-effective and far
cheaper in the long run, due to their longer life span with minimal maintenance? When
choosing what type to consider, the die is cast on the following analogy: Either design for
flexible pavements with the relatively lower initial construction costs but shorter and more
expensive lifespan, or design with rigid pavement with the initially higher costs but very low
maintenance cost over a higher life span. The economic viability, feasibility and
marketability of each type will then be known, so that policy-makers, especially in the
developing economies, may see better light. Uganda and East Africa at large needs a road
infrastructure that will not keep taking huge budget proportions every year, denying other
sectors the chance to grow professionals in the local construction industry have the old
mindset – that the rigid concrete roads are a far more expensive drain on the national
economy than the flexible bituminous roads -- and have not done adequate necessary research
to put out this old mindset. Furthermore, it is likely that policy-makers have turned a deaf ear
to sense, where some professionals may have given due guidance for informed decision-
making.
In the days when waste products from petroleum refineries had not found much use,
bitumen was cheap. Moreover, since cement and steel then were imported, concrete was
expensive. But today, with the plentiful production of cement and steel from the local
industries, the costs of concrete should compare well to asphalt. Professionals and policy-
makers have not given much attention to the cost-effectiveness of rigid pavements instead of
the flexible ones, hence the dominance of the latter.
When all is said, it is still the mindset in relation to materials, markets, methods,
management, money, manpower, which are part of the 8Ms. With researched and well-
disseminated data, coupled with a great strategic vision in terms of the 8Ms, the road
infrastructure can benefit Uganda by bringing about the desired grassroots economic, social
and technological and overall development.

The advantages and disadvantages of cement concrete pavement compared with
flexible pavement are listed. The net present value method of economic evaluation was
applied. It was found that the initial capital cost for producing rigid pavement is about twice
that of producing flexible pavement. However, the following additional costs must be
evaluated for each type of pavement:
 Annual maintenance cost, which is much lower for the concrete pavement;
 Cost of the renewal coat, this is needed every four years for the flexible pavement, but
not needed for the concrete pavement.
 Fuel cost of driving a vehicle over the pavement, which increases with its roughness;
and
 Vehicle operating cost, which also increases with pavement roughness.
The flexible pavement, unlike the concrete pavement, becomes rougher during its
working life. Assuming annual inflation and discount rates of 8% and 12%, respectively,
flexible pavement becomes more expensive than concrete pavement after about nine years.

CHAPTER 3
PAVEMENT ANALYSIS
The design of the runway is done in the following order:
 Runway orientation
 Runway length calculations
 Runway pavement
 Runway marking
 Runway lightings
The designing part is as follows:
1) Runway Orientation: The number and orientation of the runways play an important role in
the overall arrangement of various components of an airport. The number of runways will
depend on the volume of air traffic while its orientation will depend on the direction of wind
and sometimes on the extend area available for the airport development.
Wind data: The wind data i.e. the direction, duration and intensity of the wind were obtained
from Indian Metrological Department, Navi Mumbai.
2) Runway Length Calculations: The runway is designed to carry the takeoff and landing of
the largest aircraft in the world A380. The categories of the runway and their corresponding
length and width have defined by “INTERNATIONAL CIVIL AVIATION ASSOCIATION”
(ICAO). A380 falls under the category 4F and the minimum take off run is 2700m and the
width of the runway is 60m.
Wind Rose
The runway length is calculated under two constraints:
 Basic runway length
 Actual runway length
1. Basic runway length: Basic runway length is the length calculated under the following
assumed conditions,
 Airport altitude is at sea level
 Temperature at the airport is standard
 No wind is blowing on the runway
 Runway is leveled in the longitudinal direction
 Aircraft is loaded to its full capacity
 Enroute temperature is standard
 No wind is blowing enroute to the destination

Basic runway length is determined from the take off performance charts and is greater of the
either:
a) When one of the critical engines fails, the pilot has an option to continue the run or abort
the take off after attaining a certain speed called as the decision speed, if he aborts the take
off then the take off run and the stop distance should be equal.
If both the lengths are equal then the total length is called as the balanced field length.
Assume take off speed (v) = 280km/hr
The decision speed is less than or equal to the take off speed
Decision speed is less than or equal to take off speed
Hence decision speed, Vf = 280km/hr
Velocity= (280× 1000)/3600 = 78m/s
The acceleration is assumed as, a=1m/s²
Time= v/a= 78/1= 78s
Now, actual velocity is the difference between final velocity and initial velocity.
Hence, Vₐ= (Vf –Vi)/2 = (78-0)/2 = 39m/s
Hence, Total Distance (Take off Run) = 39×78=3042m
b) When all the engines are operating:
115% Of Take off run
Taking maximum value of (1) and (2),
Hence, Take Off Run from aircraft’s performance =3100m
Now, the landing length requirement Landing Run = 2050 m; Hence safe
2. Actual Runway length: Actual runway length is the length obtained after applying the
corrections of temperature, elevation and slope. The actual runway length should be adequate
to meet the operational requirements of the aircrafts for which the runway is designed and
should not be less than the longest length determined by applying the corrections for local
conditions to the operations and performance characteristics of the relevant aircraft. Local
conditions that have to be considered are temperature, elevation, slope and humidity and
runway surface characteristics. The length is calculated as follows,
a) The basic length selected for the runway should be increased at the rate of 7% per 300m
elevation.
b) The length of the runway determined should be further increase at the rate of 1% for every
1°C in the aerodrome reference temperature exceeds over standard atmosphere for the
aerodrome. If however, the total correction for elevation and temperature exceeds 35% then
the required correction should be obtained by means of specific study.
Runway take off length corrected for elevation and temperature
= [Take off run × (ART – Standard Temperature) ×.01] + Take off run

ART= Aerodrome reference temperature= Ta + ((Tm – Ta) ÷ 3)
Where,
Tm = the monthly mean of the maximum daily temperature for the hottest month of the year.
Ta = the monthly mean of the average daily temperature for the hottest month of the year.
The temperature data was available from the “Indian Metrological Department” for the period
of 1st November 2007 to 31St October 2008 and the month of March was found to be the
hottest.
c) The runway length is increased at the rate of 10% for each of 1% of the runway slope,
where the runway length is greater than 900m.
Runway take off length corrected for elevation, temperature and slope
= [Take off run × % runway slope × .10] + Take off run
The runway length obtained from correction of elevation and temperature is divided in 4
parts. The runway slope in the first quarter and the last quarter is taken as zero. In the second
quarter the slope is taken as 1.25% and in the third quarter it is taken as 0.35%.
Hence, the maximum elevation is 14.40 and the minimum elevation is 0.
Therefore the average slope is given by the equation,
= (Maximum elevation – Minimum elevation)/3
Width of the runway:
The width of the runway = 60m
Runway Shoulders: Runway shoulders must be provided to ensure a transition from the full
strength pavement to the unpaved strip of the runway. The paved shoulders protect the edge
of the runway pavement, contribute to the prevention of soil erosion by jet blast and mitigate
foreign object damage to the jet engines.
Width of the runway shoulders = 7.5m on either side of the runway
3) Runway pavements: Rigid pavements are made up of Portland cement concrete and may
or may not have a base course between the pavement and sub grade.
Rigid Pavement Design using LCN and LCG
A procedure known as load classification number system was developed by British
administrator Directorate of general works and extensive series of load test are conducted on
existing rigid pavements with different thicknesses. Based on this load test generalized
relationship between failure load and contact area of loading was developed. The load contact
is a curve for typical rigid pavement. failure loads can be obtained by this relation in this
relation w1 and w2 and failure loaded area A1 and A2 respectively the relation was found to
be applicable within contact area of 1250 cm square and 4375 cm square
In order to develop a system well the capacity of pavement to carry an aircraft could
be exercised by a single number the standard load classification curve was developed.

Arbitrary points as listed in the table below. the value listed in the table was selected since
these were typical wheel loads and contact areas of aircraft used at the time when LCN
system was developed using the standard load classification curve and the equation this
figure can be prepared one point is taken on LCN and line from Standard classification curve
the remaining points on the LCN curve are plotted using the relationship of contact area and
the load figure shows that a payment having LC and 50 is capable of bearing 50 thousand
pounds upload on contact area of 500 square inches without failure. The plate load tests are
carried out on cement concrete pavement corners. A seating load of 2267 kg is that is 5000
pounds is applied and is then released. Subsequently lodes are applied in increments of 5000
Pounds each and the deflection arrived is 5 mm .2 inches. From the plot of load v/s deflection
the failures load is recorded and the safe load is obtained by dividing the failure load by 1.5.
The design and evaluation graphs in use as shown in figure 9.29 they give the relationship
between flexural stresses in concrete pavement the LCN and LCG of aircraft the actual
subgrade characteristics and the theoretical thickness of concrete slab. The relationships word
derived from Packard programme of centre case to this figure charts 1 and chart 2 have been
added they are empirically derived from very extensive worldwide experience extending over
a considerable period of time. the outline pavement construction for 6 types of payment is
linked to the theoretical thickness they are based upon actual performance and therefore take
into account all the factors including variability from all causes temperature stresses dynamic
loading of a frequency and intensity usually referred to channelized and appropriate factor of
safety chart one contains the types of currently recommended new pavements and chart 2
includes for the evaluation purpose. Generally only the central longitudinal strips of Runway
and taxiway are subjected to channelized traffic. Aprons and hand standings are also often
intensively trafficked. For non channelized area that is the outer strips off Runway and
taxiway LCG one is lower is applicable this discretion should be used in a vehicle frequency
of usage is not directly define and where change in construction thickness would not result in
savings of cost. if the LCN of aircrafts Falls within the LCG category of channelized area of
pavement the aircraft may use the payment without restriction the published LCG of
pavement permits the authority to place no limits on its used by same or lower groups of
Aircraft for example if the pavement is rated at LCG 4 then all aircrafts in group 4 5 6 7 may
be used the payment without limitation it will always there for the present a safe loading less
than maximum loading which the payment will carry for a few load reputation without
distress it is dispersed possible to allow the occasional use of payment by high Falling within
the LCG category 1 above the published payment LCG on an infrequent basis the choice and
criteria to govern with such occasional use much we arbitrary matter representing a
reasonable balance between operational flexibility and the need to avoid undue damage to the
payment wherever payments are used by air craft with LCG higher than that of the payments
frequent inspection should you made by an experienced civil engineer increased maintenance
and expenditure and possible damage to the payment should be anticipated from both safety
and its civil engineering consideration and aircraft with LCN and evaluation which is places
in LCG category two or more higher than published payment LCG should only be allowed to
operate in emergency conditions.

Figure 8

Figure 9

Figure 10

Figure 11

Design by LCN method
Table 2
S.No ESWL
Contact
Area
Tire
Pressure
Lcn
Flex.
Stress
LCG
Group
Chart
No.
Thickness
1
58500 2500 22.82 75 3.5 3 5 425
2 31700 2500 12.7 60 3.5 3 6 350
3 6900 2100 3.4 35 3.5 4 9 225
Rigid Pavement Design Using PCA Method
The method for rigid pavement design is based on the use of influence charts
developed by Doctor Pickett through Portland cement Association using the basic equations
of Westergaard. Westergaard assume that the rigid pavement slab to be thin plastic plate
resting on subgrade which is considered as a dense liquid this account for equation P is equal
to K into Delta where is defined the subgrade wake and modulus and P is vertical reaction
proportional to the amount of deflection other assumptions of the theory of elasticity are also
observed by Westergaard in his analysis for airport Westergaard developed equation for
stresses and deflection for interior and edge locations the developed forms of the design
equations are not included here they are too cumbersome for the design use. To obtain the
allowable stress it is recommended by PCA to consider the factor of safety.
PCA method recommends that the modulus of rupture of concrete based on 28 days is
10th should be raised by 110 to 114 % of the 28 days strength on the reasoning that number
of stress occurs at only one spot by full wheel design load will be very small during the first 6
months the concrete mix food for the gain and medicinal strength of about 14%.
A special chart provided by PCA to obtain the equivalent single wheel load for
several aircraft the process that simplifies to make use of only one chart prepared for single
wheel load given in the figure.

Figure 12

Figure 13

Design by PCA method
For ESWL
Table 3
S.No ESWL K Value Tire Pressure FOS Allowable Comp. Stress Thickness
1 45000 1.5 7 2 37.5 355
2 45000 3 7 2 35.5 350
3 45000 6 7 2 35 335
1 33700 1.5 7 2 34.5 330
2 33700 3 7 2 34 320
3 33700 6 7 2 32 310
1 27000 1.5 7 2 31.7 305
2 27000 3 7 2 31 300
3 27000 6 7 2 29 285
For DWL design
Table 4
S.No DWL K Value Tire Pressure FOS Allowable Comp. Stress Thickness
1 45000 1.5 7 2 34.5 340
2 45000 3 7 2 32.5 310
3 45000 6 7 2 30.2 290
1 36000 1.5 7 2 31.5 310
2 36000 3 7 2 30.2 295
3 36000 6 7 2 28 270
1 27000 1.5 7 2 28.5 290
2 27000 3 7 2 27.5 275
3 27000 6 7 2 27 260

Rigid Pavement Design Using Faarfield
Design Considerations
The FAA computer program FAARFIELD is used for all pavement designs; there is
no longer a differentiation between pavement design for light and aircraft.
FAA Pavement Design
The design of airport pavements is a complex engineering problem that involves the
interaction of multiple variables. FAARFIELD uses layered elastic and three-dimensional
finite element-based design procedures for new and overlay designs of flexible and rigid
pavements respectively.
Rigid Pavements
For rigid pavement design, FAARFIELD uses the maximum horizontal stress at the
bottom of the PCC slab as the predictor of the pavement structural life. The maximum
horizontal stress for design is determined considering both PCC slab edge and interior
loading conditions. FAARFIELD provides the required thickness of the rigid pavement slab
required to support a given airplane traffic mix for the structural design life over a given base/
subbase /subgrade.
Stabilized Base Course
If aircraft in the design traffic mix have gross loads of 45,359 kg (100,000 pounds) or
more, then use of a stabilized base is required. Full scale performance tests have proven that
pavements which include stabilized bases have superior performance. Long term
performance gains should be considered before making substitutions to eliminate stabilized
base.
Base or Subbase Contamination
Contamination of subbase or base aggregates may occur during construction and/or
once pavement is in service. A loss of structural capacity can result from contamination of
base and/or subbase elements with fines from underlying subgrade soils. The contamination
reduces the quality of the aggregate material, thereby reducing its ability to protect the
subgrade. Geosynthetic separation fabrics can be effectively used to reduce aggregate
contamination.
Drainage Layer
Pavements constructed in non-frost areas constructed on subgrade soils with a
coefficient of permeability less than 20 ft/day (6 m/day) should include a subsurface drainage
layer. Pavements in frost areas constructed on FG2 or higher subgrade soils should include a
subsurface drainage layer. For rigid pavements the drainage layer is usually placed
immediately beneath the concrete slab. An effective drainage layer will attain 85 percent
drainage in 24 hours for runways and taxiways, and 85 percent drainage in 10 days for aprons

and other areas with low speed traffic. In the structural design of the concrete slab the
drainage layer along with the granular separation layer is considered a base layer.
Subgrade Compaction
FAARFIELD computes compaction requirements for the specific pavement design
and traffic mixture and generates tables of required minimum density requirements for the
subgrade. The values in these tables denote the range of depths for which densities should
equal or exceed the indicated percentage of the maximum dry density as specified in Item P-
152. Since compaction requirements are computed in FAARFIELD after the thickness design
is completed, the computed compaction tables indicate recommended depth of compaction as
measured from both the pavement surface and the top of finished subgrade. FAARFIELD
determines whether densities are in accordance with ASTM D 698 or ASTM D 1557 based
on weight of aircraft. ASTM D 698 applies for aircraft less than 27200 kg and ASTM D 1557
applies for aircraft 27200 kg and greater. The compaction requirements implemented in the
FAARFIELD computer program are based on the Compaction Index (CI) concept.
FAARFIELD generates two tables applicable to non-cohesive and cohesive soil types
respectively.
Pavement Life
Design Life in FAARFIELD refers to structural life. Structural life for design is
related to the total number of load cycles a pavement structure will carry before it fails.
Structural life is distinguished from functional life, which is the period of time that the
pavement is able to provide an acceptable level of service as measured by performance
indicators such as: foreign object debris (FOD), skid resistance, or roughness.
The structural design of airport pavements consists of determining both the overall
pavement thickness and the thickness of the component parts of the pavement structure. A
number of factors influence the required thickness of pavement including:
 The impact of the environment
 The magnitude and character of the airplane loads it must support.
 The volume and distribution of traffic.
 The strength of the subgrade soils.
 The quality of materials that make up the pavement structure.
Pavements on federally funded FAA projects are designed for a 20-year structural
life. Designs for longer periods may be appropriate at airfields where the configuration of the
airfield is not expected to change and where future traffic can be forecast with relative
confidence beyond 20 years. A longer design life may be appropriate for a runway at a large
hub airport where the future aircraft traffic can be forecast and where both the location and
size of the runway and taxiways is not anticipated to change. However, when designing a
taxiway at a smaller airport, it may be more prudent to design for no more than 20 years than
to forecast the composition and frequency of future activity. To achieve intended design life
all pavements require quality materials and construction combined with routine and/or

preventative maintenance. Functional life may be longer or shorter than structural life, but is
generally much longer when pavements are maintained properly.
FAARFIELD is based on three-dimensional finite element-based structural analysis
developed to calculate design thicknesses for airfield rigid pavements.
Application
The procedures and design software provide standard pavement thickness designs
meeting structural requirements for all airfield pavements. FAARFIELD design assumes that
all standard pavement layers meet the applicable requirements of AC 150/5370-10 for
materials, construction, and quality control.
Cumulative Damage Factor (CDF)
FAARFIELD is based on the cumulative damage factor (CDF) concept in which the
contribution of each aircraft type in a given traffic mix is summed to obtain the total
cumulative damage from all aircraft operations in the traffic mix. FAARFIELD does not
designate a design aircraft; however, using the CDF method, it identifies those aircraft in the
design mix that contribute the greatest amount of damage to the pavement. Thickness designs
using FAARFIELD use the entire traffic mix. Using departures of a single “design” aircraft
to represent all traffic is not equivalent to designing with the full traffic mix in the CDF
method and will generally result in excessive thickness.
Figure 14
The current version of FAARFIELD is designated Version 1.4. It has been calibrated
using the most recent full scale pavement tests at the FAA's National Airport Pavement Test
Facility (NAPTF). Due to updates to the failure models for both rigid and flexible pavements,
computed pavement thicknesses using FAARFIELD v1.4 may be different than those
computed using earlier versions of FAARFIELD. FAARFIELD can be downloaded from the
FAA website http://www.faa.gov/airports/engineering/design_software/

FAARFIELD Pavement Design Process
 Step 1: From Startup, create a new job and add the basic sections to analyze.
 Step 2: From Structure, modify the pavement structure to be analyzed.
 Step 3: From Airplane, add Airplane Load and Traffic Data.
 Step 4: Return to Structure and Design Pavement Structure.
 Step 5: Adjust Layer Thicknesses, Change Layer Types. Repeat Step 4.
 Step 6: Select Life/Compaction, print out design report.
 Step 7: Return to Startup and view pavement design report.
 Step 8: Print pavement design report to be included in engineer’s report.
FAARFIELD Material Properties
Allowable Modulus Values and Poisson’s Ratios Used in FAARFIELD
Table 5
Layer Type FAA Specified Layer
Rigid
Pavement
(MPa)
Flexible
Pavement
(MPa)
Poisson’s
Ratio
Surface
P-501 PCC 30,000 NA 0.15
P-401/P-403/P-601
HMA
NA 1,380 0.35
P-401/P-403HMA 3,000 0.35
P-306 Lean Concrete 5,000 0.2
P-304 cement treated
base
3,500 0.2
P-301 soil cement 1,700 0.2
Variable stabilized rigid 1,700 to 5,000 NA 0.2
Stabilized Base
and Subbase
Variable stabilized
NA
1,000 to
0.35
Flexible 3,000
P-209crushed
Aggregate
Program Defined 0.35
P-208, aggregate Program Defined 0.35
Granular Base and
Subbase
P-219, Recycled
concrete aggregate
P-211, Lime rock Program Defined 0.35
P-154 uncrushed
aggregate
Subgrade Subgrade 7 to 350 0.35
User-defined User-defined layer 7 to 30,000 0.35

Minimum Layer Thickness for Rigid Pavement Structures:
Table 6
Layer
Type
FAA Specification Item
Maximum Airplane Gross Weight
Operating on Pavement, kg
<5,670 < 45,360 ≥ 45,360
PCC
Surface
P-501, Portland Cement Concrete
(PCC) Pavements
125 mm 150 mm 150 mm
Stabilized
Base
P-401 or P-403; P-304; P-306
Not
Required
Not Required 125 mm
Base P-208, P-209, P-211,
Not
Required
150 mm 150 mm
Subbase P-154, Subbase Course 100 mm
As needed for frost or to
create working platform
Rigid Pavement Design
Rigid pavements for airports are composed of PCC placed on a granular or stabilized
base course supported on a compacted subgrade. The FAARFIELD design process currently
considers only one mode of failure for rigid pavement, bottom up cracking of the concrete
slab. Cracking is controlled by limiting the horizontal stress at the bottom of the PCC slab
and does not consider failure of subbase and subgrade layers. FAARFIELD iterates on the
concrete layer thickness until the CDF reaches a value of 1.0 which satisfies the design
conditions.
A three-dimensional finite element model is used to compute the edge stresses in
concrete slabs. The model has the advantage of considering where the critical stresses for slab
design occur. Critical stresses normally occur at slab edges, but may be located at the center
of the slab with certain aircraft gear configurations. FAARFIELD uses LEAF to compute
interior stress and takes the larger of 95% of the interior or 3D-FEM computed edge stress
(reduced by 25 percent) as the design stress.
Concrete Surface Layer
The concrete surface must provide a nonskid texture, prevent the infiltration of surface water
into the subgrade, and provide structural support for airplane gears. The quality of the
concrete, acceptance and control tests, methods of construction and handling, and quality of
workmanship are covered in Item P-501 Portland Cement Concrete.
Concrete Flexural Strength
The primary action and failure mode of a concrete pavement is in flexure. A design flexural
strength between 4.14 to 5.17 MPa is recommended.
Subgrade: Determination of Modulus (E Value) for Rigid Pavement Subgrade

The foundation modulus is assigned to the subgrade layer; i.e., the layer below all structural
layers. The foundation modulus can be expressed as the modulus of subgrade reaction, k, or
as the elastic (Young’s) modulus E. If the foundation modulus is input as a k-value (pci) it is
automatically converted to the equivalent E (psi) value using the following equation:
ESG = 20.15 × k1.284
FAARFIELD Calculation of Concrete Slab Thickness
FAARFIELD utilizes a three-dimensional finite element model to compute the edge
stresses in concrete slabs. The model has the advantage of considering where the critical
stresses for slab design occur. Critical stresses normally occur at slab edges, but may be
located at the center of the slab with certain aircraft gear configurations. FAARFIELD uses
LEAF to compute interior stress and takes the larger of 95% of the interior or 3D-FEM
computed edge stress (reduced by 25 percent accounting for load transfer) as the design
stress.
FAARFIELD calculates the slab thickness based on the assumption that the airplane gear
induces a maximum stress on the bottom surface of the slab. Loads that induce top-down
cracks (such as corner loads) are not considered for design. The maximum design stress may
be caused by airplane gear loading on the interior or the edge of the slab. The airplane gear
may be positioned either parallel or perpendicular to the slab edge to determine the maximum
edge stress.
Rigid Pavement Design Example
Figure 15

Airplane Information
Table 7
No. Name Gross Wt. tones
Annual
Departures
% Annual
Growth
1 B737-800 79.243 3,000 0
2 A321-200 opt 93.9 2,500 0
3 EMB-195 STD 48.95 4,500 0
4 RegionalJet-700 32.885 3,500 0
Table 8
No. Name
CDF
Contribution
CDF Max for
Airplane P/C Ratio
1 B737-800 0.04 0.05 3.52
2 A321-200 opt 0.96 0.96 3.42
3 EMB-195 STD 0 0 3.9
4 RegionalJet-700 0 0 4.71
Pavement Structure Information by Layer, Top First
Table 9
No. Type Thickness (mm) Modulus (MPa) Poisson's Ratio Strength (MPa)
1 PCC Surface 425.8 27,579.03 0.15 4.13
2
P-401/ P-403 St
(flex)
200.0 2,757.90 0.35 0.00
3 P-209 Cr Ag 304.8 206.18 0.35 0.00
4 Subgrade 0.0 51.67 0.40 0.00
Total thickness to the top of the subgrade = 930.6 mm

Figure 16

CHAPTER 4
RESULTS
FAARFIELD method
Airplanes Annual Departures
K-values
(MN/m3
)
P.C.C. layer thickness
(mm)
B737-800 3000 20 427.3
A321-200 opt 2500 27.3 425.8
EMB-195 STD 4500 40 425
RegionalJet-700 3500 60 424.7
K-values
(MN/m3
)
(mm)
B737-400 3000 20 376.1
A310-300 2500 27.3 362.8
ERJ-135 4500 40 352.7
Falcon-900 3500 60 348
K-values
(MN/m3
)
(mm)
S-75 3000 20 431
DC9-32 2500 27.3 429.8
B737-300 4500 40 427.9
A321-200 opt 3500 60 427.6
LCN method
S.No ESWL
Contact
Area
Tire
Pressure
Lcn
Flex.
Stress
LCG
Group
Chart
No.
Thickness
1 58500 2500 22.82 75 3.5 3 5 425
2 31700 2500 12.7 60 3.5 3 6 350
3 6900 2100 3.4 35 3.5 4 9 225

PCA method
For ESWL
1 45000 1.5 7 2 37.5 355
2 45000 3 7 2 35.5 350
3 45000 6 7 2 35 335
1 33700 1.5 7 2 34.5 330
2 33700 3 7 2 34 320
3 33700 6 7 2 32 310
1 27000 1.5 7 2 31.7 305
2 27000 3 7 2 31 300
3 27000 6 7 2 29 285
For DWL
1 45000 1.5 7 2 34.5 340
2 45000 3 7 2 32.5 310
3 45000 6 7 2 30.2 290
1 36000 1.5 7 2 31.5 310
2 36000 3 7 2 30.2 295
3 36000 6 7 2 28 270
1 27000 1.5 7 2 28.5 290
2 27000 3 7 2 27.5 275
3 27000 6 7 2 27 260

CHAPTER 5
CONCLUSIONS
Runway geometry and orientation along with the structural design of the flexible airfield
pavement are obtained successfully by graphical methods of design and by using software
tools which are strictly in accordance with the ICAO design criteria and FAA guidelines
(Advisory Circular).
S.No. Method Aircraft Weight (tons) Thickness(mm)
1. PCA Method (ESWL) 45 355
PCA Method (DWL) 45 340
2. LCN Method 45 388
3. FAARFIELD 45 425
 The thickness calculated by PCA Method for ESWL for a load of 45 tons is 355mm.
 The thickness calculated by PCA Method for DWL for a load of 45 tons is 340mm.
 The thickness calculated by LCN Method for a load of 45 tons is 388 mm.
 The thickness calculated by FAARFIELD Method for a load 45 tons is 425 mm.
 FAARFIELD does not calculate the thickness of layers other than the PCC slab in
rigid pavement structures, but will enforce the minimum thickness requirements for
all layers
 On comparing design for same load i.e. 45 tons by Methods LCN, PCA and
FAARFIELD we have concluded that LCN Method is more economical in
comparison to other two Method.
 From safety point of view thickness calculated from FAARFIELD is more
appropriate to be taken as FAARFIELD is in accordance with ICAO and FAA design
guidelines. FAARFIELD considers cumulative damage factor for calculation of
thickness and also gives compaction requirement for subgrade.

A Comparative Analysis on Design of Rigid Runway Pavements

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