Airport & railways engineering ce467 pdf

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AIRPORT & RAILWAYS ENGINEERING - CE467

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Chapter No 1
Introduction to Airport and Railway Engineering
Airport Engineering encompasses the planning, design, and construction of terminals, runways,
and navigation aids to provide for passenger and freight service.
Airport engineers design and construct airports. They must account for the impacts and
demands of aircraft in their design of airport facilities.
These engineers must use the analysis of predominant wind direction to determine runway
orientation, determine the size of runway border and safety areas, different wing tip to wing tip
clearances for all gates and must designate the clear zones in the entire port. OR
It involves the design and construction of facilities for the landing, take off, movement of
aircraft on the ground, parking of aeroplanes on loading aprons, maintenance and repairs of
areas, access roads from the city side to airport, and handling of passengers, baggage and
freight.
Aviation means flying with the aid of a machine, heaver than air. Commercialized aviation is
called civil aviation and is controlled by civil aviation authority.
• Airport Engineering encompasses the planning, design, and construction of terminals,
runways, and navigation aids to provide for passenger and freight service.
• Airport engineers design and construct airports. They must account for the impacts and
demands of aircraft in their design of airport facilities.
• These engineers must use the analysis of predominant wind direction to determine runway
orientation, determine the size of runway border and safety areas, different wing tip to wing tip
clearances for all gates and must designate the clear zones in the entire port.
What is an AIRPORT?
• An airport is a facility where passengers connect from ground transportation to air
transportation.
• It is a location where aircraft such as airplanes, helicopters take off and land.
• Aircraft may also be stored or maintained at an airport.
• An airport should have runway for takeoffs and landings, buildings such as hangars and
terminal buildings.
• AIRFIELD is an area where an aircraft can land and take off, which may or may not be
equipped with any navigational aids or markings. Many grass strips are also designated
as airfields.

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• AERODROMES
• A defined area on land or water (including any buildings, installations and equipment)
intended to be used either wholly or in part for the arrival, departure and surface movement of
aircraft.
Airport History
• The world's first airport was built in 1928 at Croydon near London (England). It was the main
airport for London till it was closed down in 1959, after the World War II. It is now open as a
visitor centre for aviation.
The International Civil Aviation Organization (ICAO)
• The International Civil Aviation Organization (ICAO), an agency of the United Nations, codifies
the principles and techniques of international air navigation and fosters the planning and
development of international air transport to ensure safe and orderly growth.

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International Airports
• An international airport has direct service to many other airports.
• Handle scheduled commercial airlines both for passengers and cargo.
• Many international airports also serve as "HUBS", or places where non-direct flights may land
and passengers switch planes.
• Typically equipped with customs and immigration facilities to handle international flights to
and from other countries.
• Such airports are usually larger, and often feature longer runways and facilities to
accommodate the large aircraft. (FBO, MRO etc..)
Domestic Airports
• A domestic airport is an airport which handles only domestic flights or flights within the same
country.
• Domestic airports don't have customs and immigration facilities and are therefore incapable

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of handling flights to or from a foreign airport.
• These airports normally have short runways which are sufficient to handle short/medium haul
aircraft.
Regional Airports
• A regional airport is an airport serving traffic within a relatively small or lightly populated
geographical area.
• A regional airport usually does not have customs and immigration facilities to process traffic
between countries.
• Aircraft using these airports tend to be smaller business jets or private aircraft (general
aviation).
Aircraft Characteristics
• The size;
– Span of wings: This decides the width of taxiway, size of aprons and hangers.
– Height: This decides the height of hanger gate and miscellaneous installations inside the
hanger.
– Wheel base: This decides minimum taxiway radius.
– Tail width: Required for size of parking and apron.
• Minimum turning radius: To determine the radii at the ends of the taxiways and to ascertain
the position on the loading apron.
• Gross Take-off weight: It governs the thickness of and taxiway pavements as well as length of
Runway.
• Take-off and landing distances: A number of factors such as altitude of the airport, gradient
of runway, direction and intensity of wind, temperature and the manner of landing and take-off
which influence the take-off and landing distances.
• Tyre pressure and contact area: It governs the thickness of the pavement.

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• Range: The frequency of operations and hence the peak traffic volume and the runway
capacity depend upon the normal haul length or the range.
Important Definition in Airport
Aircraft: General term which include glider, aeroplane, helicopter, rocket etc. It may be lighter
or heaver than air. It may or may not be power driven. Aeroplane is a power driven and heavier
than air flying machine. Aircraft which travels with a speed less than the speed of sound (about
1130km/hr) is called subsonic, while the aircraft travels at speed greater than the speed of
sound is called supersonic.
Airport: It is an aerodrome (area used for arrival or departure of an aircraft) which is principally
intended for the use of commercial services. It is provided with customs facility, including other
normal facilities if it serves international traffic.
Airfield: It is an area which is used for landing and take off of aircraft. It may or may not be
provided with facilities for convenience of passengers and for shelters, repair and servicing of
aircraft.
Landing area: An airport consists of landing area and terminal area. Landing area is used for
landing and take off of the aircraft. Runways and taxi ways of the aircraft are located in the
landing area.
Terminal area: It provides space for airline operations, office for airport management and
provide facilities like rest room, restaurant etc for passengers.
Apron: This is the paved area in front of terminal building (between landing area and terminal
building) for parking of the aircraft, so that the loading unloading of the passengers, baggage
can be done.
Components of an 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,
 Aircraft Stand.

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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.
A runway is the area where an aircraft lands or takes off. It can be grass, or packed dirt, or a
hard surface such as asphalt or concrete. Runways have special markings on them to help a
pilot in the air to tell that it is a runway (and not a road) and to help them when they are
landing or taking off. Runway markings are white.
Most runways have numbers on the end. The number is the runway's compass direction. (For
example, runway numbered 36 would be pointing north or 360 degrees).
Some airports have more than one runway going in the same direction, so they add letters to
the end of the number R for right, C for center, and L for left.
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 Runway: Two runway contains two runway 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: This 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.

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45 Degree Runway: 45 degree run way is opted when the wind coverage for same airfield
capacity is greater. This is also termed as four-way runway.
60 Degree Runway: 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: It 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.
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.
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.
Aircraft aprons are the areas where the aircraft park. Aprons are also sometimes called ramps.
They vary in size, from areas that may hold five or ten small planes, to the very large areas
that the major airports have.
Terminal Building: Terminal building is a place where airport administration facilities takes
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.
Also known as airport terminal, these buildings are the spaces where passengers board or alight
from flights. These buildings house all the necessary facilities for passengers to check-in their
luggage, clear the customs and have lounges to wait before disembarking. The terminals can
house cafes, lounges and bars to serve as waiting areas for passengers.
Ticket counters, luggage check-in or transfer, security checks and customs are the basics of all
airport terminals. Large airports can have more than one terminal that are connected to one
another through link ways such as walkways, sky-bridges or trams. Smaller airports usually have
only one terminal that houses all the required facilities.
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.

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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.
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 Stand: A portion of an apron designated as a taxiway and intended to provide access to
aircraft stands only.
How to Select Site for AIRPORT
Airport site selection: The selection of a suitable site for an airport depends upon the class of
airport under consideration. However if such factors as required for the selection of the largest
facility are considered the development of the airport by stages will be made easier and
economical. The factors listed below are for the selection of a suitable site for a major airport
installation: 1. regional plan, 2. airport use, 3. proximity to other airport, 4. ground accessibility,
5. Topography, 6. Obstructions, 7. Visibility, 8. Wind, 9. noise nuisance, 10. grading , drainage
and soil characteristics, 11. future development, 12. availability of utilities from town,
13. economic consideration
Regional plan: The site selected should fit well into the regional plan there by forming it an
integral part of the national network of airport.
Airport use: the selection of site depends upon the use of an airport. Whether for civilian or for
military operations. However during the emergency civilian airports are taken over by the
defense. There fore the airport site selected should be such that it provides natural protection
to the area from air roads. This consideration is of prime importance for the airfields to be
located in combat zones. If the site provides thick bushes.
Proximity to other airport: the site should be selected at a considerable distance from the
existing airports so that the aircraft landing in one airport does not interfere with the
movement of aircraft at other airport. The required separation between the airports mainly
depends upon the volume of air traffic.
Ground accessibility: the site should be so selected that it is readily accessible to the users. The
airline passenger is more concerned with his door to door time rather than the actual time in

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air travel. The time to reach the airport is therefore an important consideration especially for
short haul operations.
Topography: this includes natural features like ground contours trees streams etc. A raised
ground a hill top is usually considered to be an ideal site for an airport.
Obstructions: when aircraft is landing or taking off it loses or gains altitude very slowly as
compared to the forward speed. For this reason long clearance areas are provided on either
side of runway known as approach areas over which the aircraft can safely gain or loose
altitude.
Visibility: poor visibility lowers the traffic capacity of the airport. The site selected should
therefore be free from visibility reducing conditions such as fog smoke and haze. Fog generally
settles in the area where wind blows minimum in a valley.
Wind: runway is so oriented that landing and take off is done by heading into the wind should
be collected over a minimum period of about five years.
Noise nuisance: the extent of noise nuisance depends upon the climb out path of aircraft type
of engine propulsion and the gross weight of aircraft. The problem becomes more acute with
jet engine aircrafts. Therefore the site should be so selected that the landing and take off paths
of the aircrafts pass over the land which is free from residential or industrial developments.
Grading, drainage and soil characteristics: grading and drainage play an important role in the
construction and maintenance of airport which in turn influences the site selection. The original
ground profile of a site together with any grading operations determines the shape of an
airport area and the general pattern of the drainage system. The possibility of floods at the
valley sites should be investigated. Sites with high water tables which may require costly subsoil
drainage should be avoided.
Future development: considering that the air traffic volume will continue to increase in future
more member of runways may have to be provided for an increased traffic.
Factors affecting selection of site for Airport
• Availability of adequate area, • Accessibility, • Topography, soil condition and drainage,
• Availability of construction materials, • Cost of development, • Cost of maintenance,
• Traffic volume and type of traffic, • Cross-wind component, • Proximity of airways,
• Safety factors, • Revenues.

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Chapter No 02
Runway Orientation
According to the International Civil Aviation Organization (ICAO) a runway is a
"defined rectangular area on a land aerodrome prepared for the landing and takeoff of
aircraft".
The orientation of the runway is an important consideration in airport planning and
design. The correct runway orientation maximizes the possible use of the runway
throughout the year accounting for a wide variety of wind conditions.FAA and ICAO
regulations establish rules about runway orientation and their expected coverage
Runway Location Considerations.FAA mandates identification standards for airport
layout that is meant to assist pilots in easily recognizing runways.
Ideally, all aircraft operations on a runway should be conducted against the wind.
Unfortunately, wind conditions vary from hour to hour thus requiring a careful
examination of prevailing wind conditions at the airport site.The challenge for the
designer is to accommodate all of the aircraft using the facility in a reliable and
reasonable manner.
In navigation, all measurement of direction is performed by using the numbers of a
compass. A compass is a 360° circle where 0/360° is North, 90° is East, 180° is South,
and 270° is West, as shown in figure.
Runways are laid out according to the numbers on a compass. A runway's compass
direction is indicated by a large number painted at the end of each runway. Preceding
that number are 8 white stripes. Following that number by 500 feet is the "touchdown
zone" which is identified by 6 white stripes.
A runway's number is not written in degrees, but is given a shorthand format. For
example, a runway with a marking of "14" is actually 140 degrees. A runway with a
marking of "31" has a compass heading of 310 degrees. For simplicity, the FAA rounds
off the precise heading to the nearest tens. For example, runway 7 might have a precise

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heading of 68 degrees, but is rounded off to 70 degrees.
Each runway has a different number on each end. Look at the diagram below. One end
of the runway is facing due west while the other end of the runway is facing due east.
The compass direction for due west is 270 degrees ("27"). The compass direction for due
east is 90 degrees ("9"). All runways follow this directional layout. This runway would be
referred to as "Runway 9-27" because of its east-west orientation.
The FAA includes over 20 different runway layouts in their advisory materials. There are
4 basic runway configurations with the rest being variations of the original patterns. The
basic runway configurations are the following:
A) Single runway
This is the simplest of the 4 basic configurations. It is one runway optimally positioned
for prevailing winds, noise, land use and other determining factors. During VFR (visual
flight rules) conditions, this one runway should accommodate up to 99 light aircraft
operations per hour. While under IFR (instrument flight rules) conditions, it would
accommodate between 42 to 53 operations per hour depending on the mix of traffic and
navigational aids available at that airport.

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B) Parallel runways
There are 4 types of parallel runways. These are named according to how closely they
are placed next to each other. Operations per hour will vary depending on the total
number of runways and the mix of aircraft. In IFR conditions for predominantly light
aircraft, the number of operations would range between 64 to 128 per hour.

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If there is more than one runway pointing in the same direction (parallel runways), each
runway is identified by appending Left (L), Center (C) and Right (R) to the number —
for example, Runways Two Left (02L), Two Center (02C), and Two Right (02R).
C) Open-V runways
Two runways that diverge from different directions but do NOT intersect form a shape
that looks like an "open-V" are called open-V runways. This configuration is useful when
there is little to no wind as it allows for both runways to be used at the same time.
When the winds become strong in one direction, then only one runway will be used.
When takeoffs and landings are made away from the two closer ends, the number of
operations per hour significantly increases. When takeoffs and landings are made
toward the two closer ends, the number of operations per hour can be reduced by 50%.
D) Intersecting runways
Two or more runways that cross each other are classified as intersecting runways. This
type of configuration is used when there are relatively strong prevailing winds from

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more than one direction during the year. When the winds are strong from one direction,
operations will be limited to only one runway. With relatively light winds, both runways
can be used simultaneously.
The greatest capacity for operations is accomplished when the intersection is close to the
takeoff end and the landing threshold as shown below (with the configuration on the
left).
The capacity for the number of operations varies greatly with this runway configuration.
It really depends on the location of the intersection and the manner in which the
runways are operated (IFR, VFR,). This type of configuration also has the potential to
use a greater amount of land area than parallel runway configurations.
Factors Affecting Runway Orientation:
The direction of the runway controls the layout of the other airport facilities, such as
passenger terminals, taxiways/apron configurations, circulation roads, and parking
facilities
The following factors should be considered in locating and orienting a runway:
 Wind
 Airspace availability
 Environmental factors (noise, air and water quality)
 Obstructions to navigation
 Air traffic control visibility
 Wildlife hazards
 Terrain and soil considerations
 Natural and man-made obstructions
These are all factors in runway and airport planning. Many issues are studied before
final decisions on airport location and runway layout are determined.
Runway Lightning

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Airports also use standardized lighting and ground markings to provide direction and
identification to all air and ground crews. To assist pilots in differentiating at night
between airport runways and freeways, airports have rotating beacon lights. These
beacons usually flash green and white lights to indicate a civilian airport. They are
visible from the air long before the entire airport is recognizable. To help pilots at night
quickly identify the beginning of a runway, green threshold lights line the runway's
edge. Red lights mark the ends of runways and indicate obstructions. Blue lights run
alongside taxiways while runways have white or yellow lights marking their edges
ICAO guidance requires that Runway lighting shall not be operated if a runway is not in
use for landing, take-off or taxiing purposes, unless such operation is required for
runway inspection or maintenance purposes. ATC are required to use whatever means
are available to them to ensure that they are aware of any lighting system.

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RUNWAY SIGNS
• Various kinds of runway signs are also used for facilitation
• They differ according to their purpose and action.
Importance of the orientation and windrows

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According to the International Civil Aviation Organization (ICAO) a runway is a
"defined rectangular area on a land aerodrome prepared for the landing and takeoff of
aircraft". The orientation of the runway is an important consideration in airport planning and
design. The correct runway orientation maximizes the possible use of the runway throughout
the year accounting for a wide variety of wind conditions.FAA and ICAO regulations establish
rules about runway orientation and their expected coverage Runway Location Considerations.
FAA mandates identification standards for airport layout that is meant to assist pilots in easily
recognizing runways. Ideally, all aircraft operations on a runway should be conducted against
the wind. Unfortunately, wind conditions vary from hour to hour thus requiring a careful
examination of prevailing wind conditions at the airport site.The challenge for the designer is to
accommodate all of the aircraft using the facility in a reliable and reasonable manner.
Wind Rose Analysis
According to FAA standards, runways should be oriented so that aircraft can takeoff
and/or land at least 95 percent of the time without exceeding the allowable crosswinds
(Wright 1998). An approach often used in determining the runway orientation is called
the wind rose method. The method uses a wind rose template to arrange velocity,
direction, and frequency of wind occurrences within a certain period of time (normally
10 years or more).
On the wind rose a transparent runway template is placed to represent the proposed
runway that accommodates the size and operating characteristics of aircraft. The
template is rotated around the center of the wind rose in order to search for an optimal
runway orientation. At each rotating angle, the total percentage of allowable crosswinds
in the wind rose that are covered by the template is calculated, and a best angle that can
give the maximum percentage of coverage is determined.
Types of the airports
There are two types of airports: towered and nontowered.
Towered Airport: A towered airport has an operating control tower. Air traffic control (ATC) is
responsible for providing the safe, orderly, and expeditious flow of air traffic at airports where
the type of operations and/or volume of traffic requires such a service. Pilots operating from a
towered airport are required to maintain two-way radio communication with ATC and to
acknowledge and comply with their instructions. Pilots must advise ATC if they cannot comply
with the instructions issued and request amended instructions. A pilot may deviate from an air
traffic instruction in an emergency, but must advise ATC of the deviation as soon as possible.
Nontowered Airport: A nontowered airport does not have an operating control tower. Two-
way radio communications are not required, although it is a good operating practice for pilots
to transmit their intentions on the specified frequency for the benefit of other traffic in the
area. The key to communicating at an airport without an operating control tower is selection of
the correct common frequency. The acronym CTAF, which stands for Common Traffic Advisory
Frequency, is synonymous with this program. A CTAF is a frequency designated for the purpose
of carrying out airport advisory practices while operating to or from an airport without an
operating control tower. The CTAF may be a Universal Integrated Community (UNICOM),
MULTICOM, Flight Service Station (FSS), or tower frequency and is identified in appropriate

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aeronautical publications. UNICOM is a nongovernment air/ground radio communication
station that may provide airport information at public use airports where there is no tower or
FSS. On pilot request, UNICOM stations may provide pilots with weather information, wind
direction, the recommended runway, or other necessary information. If the UNICOM frequency
is designated as the CTAF, it is identified in appropriate aeronautical publications.
These types can be further subdivided to:
• Civil Airports: airports that are open to the general public.
• Military/Federal Government airports: airports operated by the military, National
Aeronautics and Space Administration (NASA), or other agencies of the Federal Government.
• Private Airports: airports designated for private or restricted use only, not open to the
general public. OR
International Airports: An international airport has direct service to many other airports.
Handle scheduled commercial airlines both for passengers and cargo. Many international
airports also serve as "HUBS", or places where non-direct flights may land and passengers
switch planes. Typically equipped with customs and immigration facilities to handle
international flights to and from other countries. Such airports are usually larger, and often
feature longer runways and facilities to accommodate the large aircraft. (FBO, MRO etc..).
Domestic Airports: A domestic airport is an airport which handles only domestic flights or
flights within the same country. Domestic airports don't have customs and immigration
facilities and are therefore incapable of handling flights to or from a foreign airport.
These airports normally have short runways which are sufficient to handle short/medium haul
aircraft.
Regional Airports: A regional airport is an airport serving traffic within a relatively small or
lightly populated geographical area. A regional airport usually does not have customs and
immigration facilities to process traffic between countries. Aircraft using these airports tend to
be smaller business jets or private aircraft (general aviation).
Runway Pattern

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This diagram depicts an airfield with two parallel runways, 19L and 19R. The wind is blowing
according to the Landing Direction Indicator, which in this case, is a Wind Cone, or more
informally known as a Wind Sock. IF does not have wind socks, but we do have the runways at
which we are supposed to land indicated by a color system (Green: Go, Orange: Careful, Red:
No).
##Entry
Anyway, we start with the inbound call (ie. Los Angeles Tower, American One, […], inbound for
landing). The tower will (if they are following the Airfield Pattern) sequence you into the
pattern (American One, Los Angeles Tower, enter right downwind, 19R). They may add
something like “Number 2”, or in real life, “behind a Cessna”. You then enter the pattern,
usually at a 45 degree angle, into the downwind leg. To recap based on our diagram, you are
using the bottom runway, you are landing left to right, and you are entering the downwind leg
at a 45 degree angle.
##Downwind
Not much to be said about this leg. You are flying parallel to the runway, in the opposite
direction in which you land, in other words, with the wind. If you are being controlled, the
tower may “call your base”, which means they’ll tell you when to turn 90 onto your base leg
(American One, I’ll call your base). They may also tell you to “extend downwind”, which, from
what I understand, is to continue the downwind leg until they call your base.
##Turning Base
When the tower tells your to “turn base”, you will turn 90 degrees onto your base leg.
##Base
The base leg is the leg perpendicular to the runway, at the “landing end”. This is the final leg
before final.
##Final
The final leg is the final leg before landing. The tower will clear you for landing during or slightly
before this leg (ie. Base). Side note on landing: touch and go means touch and go, not stop and
go. After a touch and go, continue following the traffic pattern.
##Go Around
When tower tells you to “go around”, they mean follow the pattern again, and do not land.
Continue flying the pattern, onto departure and crosswind legs, and then back onto downwind,
base, and final legs.
##Departure
The departure leg is the leg after clearing the runway, against the wind. From the departure leg,
you can depart, or go back around the pattern (hence the “remaining in the pattern” request
before takeoff). Departing straight out, north, south, east, or west are the directions you can
request in IF. After this leg, you can remain in the pattern by turning 90 degrees onto the
crosswind leg.
##Crosswind
The crosswind leg is the leg perpendicular to the runway, at the opposite end of the runway
you land on. After this leg, you can turn 90 degrees onto the downwind leg.
#Conclusion and Notes

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This is my understanding of the airfield pattern, and I am not an IRL pilot, or officially training to
be one. Please comment/edit if I explained something wrong.
##Some other notes
-When flying at an uncontrolled airport (Unicom), you usually state the leg you’re flying in
(American One is on right base, Runway 19R).
-The Diagram states a “No Transgression Zone”. This just means that since the two runways are
parallel, the pattern does not have a left or right side, respectively. This applies to airports with
parallel runways, such as KLAX or KSFO.
-The airfield traffic pattern altitude is generally 800-1000ft AGL (Above Ground Level).
-If helicopters do come, I’ll make a new tutorial for that.
-One of the things I find pilots do a lot is request
takeoff, remaining in the pattern, and proceed to depart. Remaining in a pattern means you are
continuing the pattern, turning onto crosswind after takeoff, then onto downwind, etc. If you
wish to depart, request departure, or state intention to depart in your request to takeoff.
-Left and right sides of the runway are the left and right sides of the runway when you take off,
sounds kind of obvious, but trust me, I’ve seen it all, and done it all.
-Please correct me in the comments, if necessary, and I am sorry if this is a duplicate. Hope this
helps!
Diagram, this time for a single runway:
Factors affecting the length of the runway with numerical
Basic Runway Length: It is the length of runway under the following assumed conditions at the
airport: The basic runway length is determined from the performance characteristics of the
aircrafts using the airport. The following cases are usually considered
 Normal landing case,  Normal take-off case,  Engine failure case.
 For jet engine aircrafts all 3 cases are considered
 For the piston engine aircraft only 1st and 3rd cases are considered
 The case which works out the longest runway length is finally adopted.
1) Normal landing case: The landing case requires that aircraft should come to stop within
60% of the landing distance. The runway of full strength pavement is provided for the entire
landing distance.
2) Normal take-off case: The normal take-off case requires a clearway which is an area beyond
the runway and is in alignment with the centre of runway.
The width of clearway should not be less than 150 m and is also kept free from obstructions.

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3) Engine failure case: The engine failure case may require either a clearway or a stopway, or
both.  Stopway is described as an area beyond the runway and centrally located in
alignment with the centre of runway.  It is used for decelerating during an aborted
(terminated) take-off.  The strength of stopway pavement should be just sufficient to carry
the weight of aircraft without causing any structural damage to the designated engine failure
speed, the pilot decelerate the aircraft and makes use of the stopway.
1. Airport altitude is at the sea level. 2. Temperature at the airport is standard (150C)
3. Runway is leveled in the longitudinal direction (zero gradient). 4. No wind is blowing on the
runway. 5. Aircraft is loaded to its full loading capacity.
Runway Length Corrections: The basic runway length is for mean sea level having standard
atmospheric conditions, necessary corrections are therefore applied after determining the basic
runway length are: 1. Correction for Elevation. 2. Correction for Temperature
3. Check for total correction for Elevation and Temperature. 4. Correction for Gradient.
Correction for Elevation: As the elevation increases, the air density reduces. This in turn
reduces the lift on the wings of the aircraft and the aircraft requires greater ground speed
before it can rise into the air. To achieve greater speed, longer length of runway is required.
ICAO recommends that the basic runway length should be increased at the rate of 7% per 300
m (1000 ft) rise in elevation above the main sea level.
L1 = 7/100LBx Elevation/300
L1 = LB + L1
Correction for Temperature
T = Ta + Tm - Ta /3
T = Airport reference temperature
Ta = Monthly mean of average daily temperature for the hottest month of the year
Tm = Monthly mean of maximum daily temperature for same month of the year
Standard temperature Ts = 150C – 0.0065* Elevation
T = T – Ts ,
L2 = (L1/100) * T
L2 = L1 + L2
Check for Total correction for Elevation and Temperature: ICAO further recommends that, if
the total correction for elevation plus temperature exceeds 35% of the basic runway length:
L2 – LB/LBx100 35%
Correction for Gradient: Temperature should be increased at 20% for every 1 percent of
effective gradient, • Effective gradient is defined as the maximum difference in elevation
between the highest and lowest points of runway divided by the total length of runway.
Geff = max Elev  min Elev/ L2 *100%
L3 = 20/200 xL2xGeff
L3 = L2 + L3
Example: The monthly mean temperature of the atmosphere at a particular site where an
airport is to be developed, are given below. Determine the airport reference temperature. If

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the site is at mean sea level determine the actual runway length. The runway is assumed to be
level.
Month Temperature Month Temperature
Mean Aver
Daily
Mean Max
Daily
Mean Aver
Daily
Mean Max
Daily
January 3 5 July 32 37
February 15 17 August 30 35
March 20 23 September 27 31
April 25 32 October 22 28
May 35 47 November 12 18
June 40 50 December 6 9
Solution: The table indicate that the hottest month of the year is June. Hence the mean of
Maximum daily temperature, Tm = 500C
Mean of average daily temperature, Ta= 400C
Airport reference temperature: T = Ta + Tm - Ta /3
= 40 + 50 – 40/3 + 43.330 C.
Suppose the basic runway length= L meters.
Standard atmospheric temperature at mean sea level (150C ).
The rise of temperature = 43.330- 150= 28.330C
The required correction: L  L/100*28.33
The corrected length = L + 0.2833 L = 1. 2833 L meters
No correction for elevation or gradient is required
Example: The length of runway under standard conditions is 1620 m. the airport site has an
elevation of 270 m. its reference temperature is 32.9 0C. If the runway is to be constructed with
an effective gradient of 0.2 percent, determine the corrected runway length.
1. Correction for elevation
Solution: L1 7/100 x1620 x 270/300 =102m
Corrected length = 1620 + 102 = 1722 m
2. Correction for temperature
Standard atmospheric temp Ts = 150
C – 0.0065* 270 = 13.180
C
Rise of temp T = 32.9 – 13.18 = 19.720
C
L2 1722/100 x19.72 = 340m
Corrected length = 1722 + 340 = 2062 m
3. Check for total correction of Elev. and Temp.
= 2062 – 1622/1620 x100 = 27.2 percent < 35%.
4. Correction for gradient
L3 20/100 x2062 x 0.20 =82.48m
Corrected length = 2062 + 82.48 = 2144.48 m rounding this value to the nearest 10 meters,
Corrected Runway Length = 2150 m.

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Chapter No 03
Introduction to Railway Engineering
It is a branch of civil engineering concerned with the design,
construction, maintenance, and operation of railways. Railway engineering includes elements
of civil, mechanical, industrial, and electrical engineering. Railway engineers handle the design,
construction, and operation of railroads and mass transit systems that use a fixed guideway
(such as light rail or even monorails). Typical tasks would include determining horizontal and
vertical alignment design, station location and design, construction cost
estimating, and establishment of signaling & controlling system. Railroad engineers can also
move into the specialized field oftrain dispatching which focuses on train movement control.
IMPORTANT DEFINITION RAILWAYS ENGINEERING
There are many important technical terms concerning to Railways, but a few terms which are
of immediate concern are only discussed bellow:-
1. Railway track:-A track formed of rails of iron or steel along which trains are driven is known
as railway track.
In general, the term railway also includes all lines of rails, sidings or branches.
2. Rolling stock:- The locomotives, passenger coaches and goods wagons which roll or run on
railway tracks constitute rolling stock.
3. Locomotive:- The mechanical device which transfers chemical energy of fuel into
mechanical energy in the form of motion is called locomotive. The fuel used in the locomotives
may be in the form of water and coal, diesel or electricity.
4. Wagons :- The goods compartments are called wagons. This term applies only to
good stock.
5. Coaches or vehicles :- The passenger compartments are called coaches or vehicles.
This term applies only to coaching stock.
6. Siding: when a branch starting from main line terminates at the dead end with a buffer stop
is known as siding.
7. Ballast: is the granular material packed under and around the sleepers to transfer the loads
from the sleepers to subgrade.
RAILS
A rail is a steel bar extending horizontally between supports which is used as a track for rail
road, cars or other vehicles.
The high carbon rolled steel sections, which are laid end-to-end, in two parallel lines over
sleepers to provide continuous and leveled surface for the trains to move and for carrying axle
loads of the rolling stock are called rails.

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Functions of the rails:
To provide continuous and level surface for the movement of trains with minimum friction
with steel wheels of the rolling stock;
Provide strength, durability and lateral guidance to the track;
Transmit the axle loads to sleepers which transfer the same load to the underlying ballast and
formation;
Bear the stresses developed due to heavy vertical loads, breaking forces and temperature
variance.
Types of Rails
Rails can be divided in three types
1. Double Headed Rails. 2. Bull Headed Rails. 3. Flat Footed Rails.
1. Double Headed Rails: These rails indicate the early stage of development. It essentially
consists of three parts:  Upper Table,  Web,  Lower Table.
Both the upper and lower tables were identical and they were introduced with the hope of
double doubling the life of rails. When the upper table is worn out then the rails can be placed
upside down reversed on the chair and so the lower table can be brought into use. But this idea
soon turned out to b wrong because due to continuous contract of lower table with the chair
made the surface of lower table rough and hence the smooth running of the train was
impossible. Therefore, this type of rail is practically out of use. Nowadays, these rails vary in
lengths from 20 – 24.

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2. Bull Headed Rails: This type of rail also consists of three parts,
 The Head,  The Web,  The Foot.
These rails were made of steel. The head is of larger size than foot and the foot is designed only
to hold up properly the wooden keys with which rails are secured. Thus, the foot is designed
only to furnish necessary strength and stiffness to rails. Two cast iron chairs are required per
each sleeper when these rails are adopted. Their weight ranges from 85lb to 95lb and their
length is up to 60 ft.
3. Flat Footed Rails: These rails were first of all invented by Charles Vignoles in 1836 and hence
these rails are also called vignols rails. It consist of three parts:
 The Head,  The Web,  The Foot.

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The foot is spread out to form a base. This form of rail has become so much popular that about
90% of railway tracks in the world are laid with this form of rails.
Flat footed rails has the following advantages
 They do not need any chair and can be directly spiked or keyed to the sleepers. Thus they are
economical.
 They are much stiffer both vertically and laterally. The lateral stiffness is important for curves.
 They are less liable to develop kinks and maintain a more regular top surface than bull headed
rails.
 They are cheaper than bull headed rails.
 The loads from wheels of trains are distributed over large number of sleepers and hence
larger area which results in greater track stability, longer life of rails and sleepers, reduced
maintenance, costs, less rail failure and few interruptions to traffic.
Wear of Rails
The separation or cutting of rail due to friction and abnormal heavy load is called wear. There
are three types of wears of rail.
1. Wear of Rails on top OR Head of Rail. 2. Wear at the End of Rails,
3. Wear at the side of head of Rails.
Wear is one of the prominent defects of rails. Due to heavy loads concentrated stresses
exceeds the elastic limit resulting in metal flow; on the gap or joints the ends are battered and
at the curves the occurrence of skidding, slipping and striking of wheel flanges with rails results
in wear and tear on rails.
Classification of wear
• On the basis of location
I. On sharp curves
II. On gradients

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III. On approach to stations
IV. In coastal area etc.
• On the basis position of wear
I. On the top of rail
II. At the end of rail
III. on the sides of the head
Methods for Reducing Wear of Rails
The following methods are adopted for reducing wear of rails.
1. Use of Special Alloy Steel, 2. Good Maintenance of Track, 3. Reduction of Expansion Gap,
4. Exchange of Inner and Outer Rails on Curves, 5. Use of Lubricating Oil.
• When wear exceeds the permissible limit (5 % of the total weight section) the rail must be
replaced.
• Use of special alloy steel at the location where wear is more.
• Reduction in number of joints by welding

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• Regular tightening of fish bolts and packing of ballasts.
• Welding and dehogging of battered ends in time also the wear.
• Maintenance of correct gauge will reduce the side wear in particular.
• Lubricating of the gauge face of outer rail on curve, will also reduce the wear.
• Interchanging of inner and outer rails and changing face at curve will reduce the wear.
• Application of heavy mineral oil, in case of corrosion of rail metal under adverse
atmospheric conditions, reduce the wear of rail.
Coning of Wheels
The rim or flanges of the wheels are never made flat but they are in the shape of a cone with a
slope of about 1 to 20. This is known as coning of wheels.
The rim or flanges of the wheels are never made flat but they are in the shape of a cone with a
slope of about 1 to 20. This is known as coning of wheels. The coning of wheels is manly done
to maintain the vehicle in the central position with respect to the track. When the vehicle is
moving on leveled track then the flanges of wheels have equal circumference.
But when the vehicle is moving along a curved path then in this case the outer wheel has to
cover a greater distance then that of inner wheel. Also as the vehicle has a tendency to move
sideways towards the outer rail, the circumferences of the flanges of the inner wheel and this
will help the outer wheel to cover a longer distance than the inner wheel. In this ways smooth
riding is produced by means of coning of wheels.
The distance between the inside edges of wheel flanges is generally kept less than the gauge.
Gap is about 38 mm on Either side. Normally the tyre is absolutely ahead centre on the head of
the rail, as the wheel is coned to keep it in this central position automatically. These wheel are
coned at a slope
• Theory of coning:- On a level track, as soon as the axle moves towards one rail, the diameter
of the wheel tread over the rail increases, while It decreases over the other rail. This prevents
to further movement And axle retreats back to its original position (with equal dia or both rails
and equal pressure on both rails).
Coning of wheels on level-track
Coning Wheels Disadvantages: Coning wheels has the following disadvantages:

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1. In order to minimize the above below disadvantages the tilting of rails is done. i.e. the rails
are not laid flat but tilted inwards by using inclined base plates sloped at 1 in 20 which is also
the slope of coned surface of wheels.
2. The pressure of the horizontal component near the inner edge of the rail has a tendency to
wear the rail quickly.
3. The horizontal components tend to turn the rail outwardly and hence the gauge is widened
sometimes.
4. If no base plates are provided, sleepers under the outer edge of the rails are damaged.
5. In order to minimize the above mentioned disadvantages the tilting of rails is done. i.e. the
rails are not laid flat but tilted inwards by using inclined base plates sloped at 1 in 20 which is
also the slope of coned surface of wheels.
Advantages of Tilting of Rails
 It maintains the gauge properly.  The wear at the head of rail is uniform.
 It increases the life of sleepers and the rails.
Railway Gauges - Types of Railway Gauges
Gauge is the measure of distance between the railroad rails. The distance is usually measured
from the inside top edge of the parallel rails.
The clear horizontal distance between the inner (running) faces of the two rails forming a
track is known as Gauge. (see in fig given below). This gauge of 1435 mm has been universally
used in Great Britain, France, Germany, U.S.A., Canada and most other countries of Europe and
is thus known as the world standard gauge. In India broad gauge used which has standard size
1676 mm.
The different gauges prevalent in India are of the following these types :-
1. Broad gauge (1676),
2. Metre gauge (1000),
3. Narrow gauge (762 mm & 610 mm).

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Broad Gauge (5 ft to 5 ft 6 inches): Broad gauges are useful for heavy loads and higher rates of
speed. Broad-gauge railways are standard in Russia, Finland, Ireland, India, Sri Lanka, Pakistan,
Nepal, Bangladesh, Portugal, and Spain.
When different gauges adjoin, for example at a nation's border, a break of gauge occurs. Some
lines solve the problem by building dual gauge lines, which contain several different rails on a
single rail bed for different gauges. Dual-gauge railways are in use in Australia, Argentina, Brazil,
Vietnam, and Switzerland. Some locomotives and rail cars are built with adjustable wheels that
can adapt to different gauge sizes.
When the clear horizontal distance between the inner faces of two parallel rails forming a
track is 1676mm the gauge is called Broad Gauge (B.G)
This gauge is also known as standard gauge of India and is the broadest gauge of the world.
The Other countries using the Broad Gauge are Pakistan, Bangladesh, SriLanka, Brazil,
Argentine,etc.50% India’s railway tracks have been laid to this gauge.
Suitability for Broad Gauge:-
Broad gauge is suitable under the following Conditions :-
(i) When sufficient funds are available for the railway project.
(ii) When the prospects of revenue are very bright. This gauge is, therefore, used for tracks in
plain areas which are densely populated i.e. for routes of maximum traffic, intensities and at
places which are centers of industry and commerce.
Meter Gauge: This type is 3 ft 6 inches or 1.069 meter, mostly used in Japan, South Africa and
New Zealand.
When the clear horizontal distance between the inner faces of twoparallel rails forming a
track is 1000mm, the gauge is known as Metre Gauge (M.G)
The other countries using Metre gauge are France, Switzerland, Argentine, etc. 40% of
India’s railway tracks have been laid to this gauge.
Suitability for Metre Gauge:-
Metre Gauge is suitable under the following conditions:-
(i) When the funds available for the railway project are inadequate.
(ii) When the prospects of revenue are not very bright.
Narrow Gauge (2 ft to 2 ft 6 inches): Some railroads use smaller distances, known as narrow
gauge railroads. Narrow-gauge railways are cheaper to build and better adapted to
mountainous terrain. Some narrow gauges are in use in mining operations, and in short-run
railroads that must account for sharp curves and steep slopes. However, narrow-gauge railways
are limited in their weight capacity and operating speed.
When the clear horizontal distance between the inner faces of two parallel rails forming a track
is either 762mm or 610mm, the gauge is known as narrow gauge (n.g) the other countries using
narrow gauge are britain, south africa, etc. 10% of india’s railway tracks have been laid to this
gauge.
Suitability for Narrow Gauge:-
Narrow gauge is suitable under the following conditions :-
( i) When the construction of a track with wider gauge is prohibited due to the provision of
sharp curves, steep gradients, narrow bridges and tunnels etc.
(ii) This gauge is, therefore, used in hilly and very thinly populated areas. The feeder gauge is

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commonly used for feeding raw materials to big government manufacturing concerns as well as
to private factories such as steel plants, oil refineries, sugar factories, etc.
Standard Gauge: Standard gauge probably in many countries of the world is 1435 mm. This
measurement was developed by George Stephenson, a British railway engineer, using the width
of coal wagons that were in use before the invention of the steam locomotive. In the United
States, gauge can vary slightly between 4 feet, 8.5 inches to 4 feet, 9.5 inches (1,460 mm).
All rail cars and locomotives built to this specification can use any standard gauge railroad line
in the world. However, not all railroads have been built to standard gauge.
Advantages of Breaking the Gauge :-
i). The most effective advantage of breaking the gauge is to render the railway an economical
and profitable concern.
ii). It facilitates the provision of a steeper gradient, sharp curves and narrow tunnels by
adopting a less wide gauge in hilly and rocky areas.
DisAdvantages of Breaking the Gauge :-
Difference in Gauges: Gauge should be uniform otherwise it will cause problem for passengers
as they have to change train where there are two different gauges
 No suitable for commercial goods. There will be load and unload of goods and will
increase the cost of goods imported or exported
 Will require wagons of different gauges, thus create shortage or over crowed of wagons
 Difficult in an emergency or in war if it is needed to transfer army or people from one
corner of the country to the other
 For different gauges, there will require a station consist of duplicate facilities such as
platform, siding etc.
Following are the factors affecting the choice of a gauge:

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1. Traffic Condition: If the intensity of traffic on the track is likely to be more, a gauge
wider than the standard gauge is suitable.
2. Development of Poor Areas: The narrow gauges are laid in certain parts of the world to
develop a poor area and thus link the poor area with the outside developed world.
3. Cost of Track: The cost of railway track is directly proportional to the width of its gauge.
a) If the fund available is not sufficient to construct a standard gauge, a metre gauge or a
narrow gauge is preferred rather than to have no railways at all.
4. Speed of Movement: The speed of a train is a function of the diameter of wheel which
in turn is limited by the gauge.
a) The wheel diameter is usually about 0.75 times the gauge width and thus, the speed of a
train is almost proportional to the gauge.
b) If higher speeds are to be attained, the broad gauge track is preferred to the metre
gauge or narrow gauge track.
5. Nature of Country: In mountainous country, it is advisable to have a narrow gauge of
the track since it is more flexible and can be laid to a smaller radius on the curves.
a) This is the main reason why some important railways, covering thousands of kilometers,
are laid with a gauge as narrow as 610 mm.
Advantages and disadvantages of different track gauges
Narrow gauge railways usually cost less to build because they are usually lighter in construction,
using smaller cars and locomotives (smaller loading gauge), as well as smaller bridges, smaller
tunnels (smaller structure gauge) and tighter curves. Narrow gauge is thus often used in
mountainous terrain, where the savings in civil engineering work can be substantial. It is also
used in sparsely populated areas, with low potential demand, and for temporary railways that
will be removed after short-term use, such as for construction, the logging industry, the mining
industry, or large-scale construction projects, especially in confined spaces.
Broader gauge railways are generally more expensive to build, but are able to handle heavier
and faster traffic.

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Chapter No 04
BALLAST
Ballast in railroad terminology is durable granular material placed between
the crosstie and the sub ballast to hold the track in line and grade. Railway Ballast is the
foundation of railway track and provide just below the sleepers. The loads from the wheels of
trains ultimately come on the ballast through rails and sleepers.
It is a layer of broken stone, gravel, moorum or any other gritty (sand) material placed & packed
below & around sleepers for distributing the load from the sleepers to the formation & for
providing drainage as well as giving longitudinal & lateral stability to the track.
Functions of Ballast
Some of the important functions of railway ballast are:
 To provide firm and level bed for the sleepers to rest on
 To allow for maintaining correct track level without disturbing the rail road bed
 To drain off the water quickly and to keep the sleepers in dry conditions
 To discourage the growth of vegetation
 To protect the surface of formation and to form an elastic bed
 To hold the sleepers in position during the passage of trains
 To transmit and distribute the loads from the sleepers to the formation
 To provide lateral stability to the track as a whole
 Provides a hard and level bed for the sleepers and hold the sleepers in place during the
passage of train,
 It transmits and distributes the load from the sleepers to the formation,
 Ballast allows for maintaining correct track levels without disturbing the rail road bed,
 It protect the surface of formation,
 Drain the water immediately, and
 Keeps the sleepers in dry condition and discourage the growth of vegetation
 On curves the ballast quantity will be slightly more to cover super-elevation

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 Ballast maximum size is 1.9 to 5.0 cm with some reasonable proportion of intermediate
sizes. It should be spread up to the top of the sleepers and not on top of sleepers
 The slope will be 1:1 or 1.5:1
 The depth/thickness of ballast should be 6 inch to 24 inches. The depth is measured
from top of sub grade to bottom of sleepers
 The ballast top should be 0.5 to 1.0 inch below the rail bottom to allow rain water flow.
 Provide level & hard bed for sleepers.
 Hold Sleepers in position.
 Transfer & distribute load to wide area.
 Provide elasticity & resilience to track.
 Provide longitudinal & lateral stability.
 Provide effective drainage.
 Maintain level & alignment of track.
Requirements for Ideal Ballast
The ideal material for ballast should fulfill the following requirements.
 It should be possible to maintain the required depth of the material in order to
distribute the load of passing train on the formation ground
 The material to be used for ballast should not be too rigid but it should be elastic in
nature
 The material for ballast should be of such nature that it grips the sleepers in position
and prevent their horizontal movement during passage of train
 It should not allow the rain water to accumulate but should be able to drain off the
water immediately without percolating
 It should be strong enough a resistance to abrasion.
 It should be tough and should not crumble under heavy loads.
 It should be cubical shape & angular shape with sharp edges.
 It should be able to non-porous & non-water absorbent particles of ballast are usually
more durable due to better resistance .
 It should not make the track dusty or muddy.
 It should offer resistance to abrasion and weathering.
 It should not produce any chemical reaction with rails and sleepers.
 It should provide good drainage system.
 The size of stone ballast should be 5cm for wooden sleepers, 4cm for metal sleepers &
2.5 cm for turnouts & crossovers.
 It should be cheep & economical or the ballast should be available in nearest quarries.
 In short, the ballast should be such which fulfils the characteristics of strength, clean
ability, durability, economy & stability.
Materials for Ballast: The following materials are used for ballast on the railway track.
 Broken Stone,  Gravel,  Cinders / Ashes,  Sand,  Kankar,  Moorum,
 Brick Ballast,  Selected Earth.

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Tests on ballast: Ballast material quality is defined by its particle characteristics. Therefore
testing of ballast material is required to define these characteristics.
Tests for ballast material:
Durability tests: Three abrasion tests are mainly using:
Los Angeles abrasion: it’s a dry test to measure toughness or tendency for breakage of
aggregate. It consists 12 steel balls in a large steel drum for 1000 revolutions. Impact of steel
balls cause crushing on ballast. Material from the test should sieve with 1.7 mm sieve.
The LAA value =((w₁-w₂)/ w₁)×100, Here, w₁= total weight of specimen
w₂= weight of material retained on the 1.7 mm sieve.
Crushing test: To test resistance of an aggregate to crushing under wheel loads.
• The aggregate passing 12.5 mm IS sieve and retained on 10 mm IS sieve is selected for
standard test. Material is placed in a steel mould of 150 ×180 mm deep.
• Load is applied through the plunger at a uniform rate of 4 tonnes per minute until the total
load is 40 tonnes, and then the load is released. Aggregate crushing value = (w₂/ w₁) ×100,
Here, Total weight of dry sample taken = w₁
Weight of the material passing through 2.36mm sieve = w₂.
Impact test: It measures the toughness to sudden shocks and impact loads.
Aggregate size of passing through 12.5mm sieve and retained on 10 mm sieve placed in a steel
mould. Subjected to 15 blows with 14 kg weight of hammer at a height of 380mm.
Aggregate impact value = (w₂/ w₁) ×100, Here, Total weight of dry sample taken = w₁
Weight of the material passing through 2.36mm sieve = w₂.
Shape tests: Flakiness index: The flakiness index of aggregates is the percentages by weight of
particles whose least dimension(thickness) is less than 0.6 of their mean dimension.
Elongation index: The elongation index of an aggregate is the percentage by weight of particles
whose greatest dimension (length) is greater than 1.8 times of their mean dimension. The
elongation test is not applicable to sizes smaller than 6.3 mm.
SLEEPERS
Sleepers are members generally laid transverse to the rails, on which the rails are supported &
fixed, to transfer the loads from the rails to the ballast and the sub grade.
It is a component of permanent way laid transversely under the rails and performing the
following functions.
1. To support the rails firmly and evenly
2. To maintain the gauge of the back correctly
3. To distribute the weight common on the rails over a sufficiently large areas of the ballast
4. To act as an elastic medium between the rail and the ballast and to absorb the vibrations of
the trains.
5. To maintain the track at proper grads
6. To align the rail properly
Sleepers - Functions
 Holding rails to correct gauge and alignment.
 Firm and even support to rails.
 Transferring the load evenly from rails to wider area of ballast.

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 Elastic medium between rails and ballast.
 Providing longitudinal and lateral stability
Sleepers - Requirements
 The sleepers to be used should be economical, i.e they should have minimum possible initial
& maintenance cost.
 Moderate weight – easy to handle.
 Fixing & removing of fastenings should be easy.
 Sufficient bearing area.
 Easy maintenance & gauge adjustment.
 Track circuiting (electric insulation) must be possible.
 Able to resist shocks & vibrations.
Characteristics of Ideal Railway Sleepers
1. Initial cost and maintenance cost should be low
2. They should resist weathering, corrosion, decay and other deterioration
3. They should bear the wheel load efficiently and satisfactorily
4. They should maintain the correct gauge
5. They should absorb shocks or vibrations due to moving vehicles
6. It should distribute the load properly and uniformly over the ballast
7. Fastenings of rail with sleepers should be strong and simple
8. They should not break while packing of ballast
9. Weight should not be low or high
Types of sleepers:
1. Wooden Sleepers
These are commonly 254mm wide by 127mm thick in cross section by 2600 mm long. The
sleepers are first seasoned (drying for up to 12 months so that to remove the juice/sap) and
treated with preservative. Creosote is an oil generally used/ sprayed on the surface. They are
either hard wood or soft wood type.
Wooden sleepers are the ideal type of sleeper. Hence they are universally used. The utility of
timber sleepers has not diminished due to the passage of time.
Switch Ties: The primary use for switch ties is to transfer load (as from the name) and are made
of hard wood. This type is preferably used in bridge approaches, heavily traveled, railway
crossovers and as transition ties.
Softwood Ties: softwood timber is more rot (decay) resistant than hardwood, but does not
offered resistance to spike hole enlargement, gauge spreading, also are not as effective in
transmitting the load to the ballast section as the hardwood tie. Softwood ties and hardwood
ties should not be mixed on the main track. Softwood ties are typically used in open deck
bridges.
Concrete Ties: Concrete ties are rapidly gaining acceptance for heavy haul mainline use as well
as for curvature greater than 2 degree. They are made of RCC or pre-stressed
concrete containing reinforcing steel wires.
An insulator plate is placed between rail and tie to isolate the tie electrically.

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Advantages of Wooden Sleepers: They are cheap and easy to manufacture.  They are easy to
handle without damage.  They are more suitable for all types of ballast.  They absorb shocks
and vibrations better than other types of sleepers.  Ideal for track circuited sections.  Fittings
are few and simple in design.  Good resilience.  Ease of handling.  Adaptability to non
standard situation.  Electrical insulation.
Disadvantages of Wooden Sleepers: They are easily liable to attack by vermin and weather. 
They are susceptible to fire.  It is difficult to maintain gauge in case of wooden sleepers. 
Scrap value is negligible.  Their useful life is short about 12 to 15 years.
2. Steel Sleepers:
Steel ties are used where wood or concrete is not favorable, for example in tunnels with limited
headway clearance. They are also used in heavy curvature prone to gage widening. This type of
steel ties can cause problem to signals control system. Some problem of fatigue cracking have
also experienced. Due to the increasing shortage of timber in the country and other economic
factors have led to the use of steel and concrete sleepers on railways.
In the design of Steel sleeper, the following are considered:  It should maintain perfect gauge.
 Can fix the rail and there should be no movement longitudinally.  Should have sufficient
effective area to transfer load from rail to ballast.  The metal of sleepers should be strong
enough to resist bending.  The design life should be 35 years.
Advantages of Steel Sleepers: It is more durable. Its life is about 35 years.  Lesser damage
during handling and transport.  It is not susceptible to vermin attack.  It is not susceptible to
fire.  Its scrap value is very good.
Disadvantages of Steel Sleepers: It is liable to corrosion.  Not suitable for track circuiting.
 It can be used only for rails for which it is manufactured.  Cracks at rail seats develop during
the service.  Fittings required are greater in number.
3. Cast Iron Railway Sleepers:
They are further divided into two categories:
 Cast iron pot type sleepers.  Cast iron plate type sleepers.
Advantages of Cast Iron Sleepers: Service life is very long.  Less liable to corrosion.  Form
good track for light traffic up to 110 kmph as they form rigid track subjected to vibrations under
moving loads without any damping.  Scrap value is high.
Disadvantages of Cast Iron Sleepers: Gauge maintenance is difficult as tie bars get bent up.
 Not suitable for circuited track.  Need large number of fittings.  Suitable only for stone
ballast.  Heavy traffic and high speeds (>110kmph) will cause loosening of keys and
development of high creep.
4. Concrete Railway Sleepers:
They have design life of up to 40 years. They can easily be moulded into the required/design
shape to withstand stresses induced by fast and heavy traffic. The added weight helps the rail
to resist the forces produced due to thermal expansion and which can buckle the track. The
weight of concrete sleepers is about 2.5 to 3 time the wooden sleepers. Pre-tensioned concrete
sleepers are usually preferred now days

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Reinforced Concrete and prestressed concrete sleepers are now replacing other types of
sleepers except in some special circumstances like bridges etc. where wooden sleepers are
used. Concrete sleepers may be of two types:
 Mono Block Concrete Sleepers.  TWIN BLOCK Concrete sleepers.
Characteristics/Requirements of an ideal sleeper:
An ideal sleeper should possess the following characteristics.
• Sleeper should be economical i.e, minimum initial and maintenance cost.
• Fitting of the sleepers should be easily adjustable during maintenance operations.
Such as: ✓Lifting, ✓Packing, ✓Removal and replacements.
The weight of the sleeper should not be too heavy or excessively light i.e. with moderate
weight they should be for ease of handling.
✓Design of sleepers should be such a way that the gauge and alignment of track and levels of
the rails can easily adjusted and maintained.
✓The bearing area of sleepers below the rail seat and over the ballast should be enough to
resist the crushing due to rail seat and crushing of ballast under sleepers.
✓Design and spacing such a way to facilitate easy removal and replacement of ballast.
Sleepers should be capable of resisting shocks and vibrations due to passage of heavy loads of
high speed trains.
• Sleepers design should be such a way they are not damaged during packing process.
• Design should be strong enough so that they are not pushed out easily due to the moving
trains especially in case of steel sleepers with rounded ends.
• An ideal sleeper should be anti-sabotage and anti-theft qualities.
Treatment of Wooden Sleepers
Untreated railway sleepers are prone to attack by decay and vermin. The life of untreated
wooden sleepers is thus very less. The life of untreated sleepers can be prolonged considerably
b treatment. An extra life of 30-50% is estimated for treated railway sleepers over untreated
railway sleepers.
The fibers of wood contain millions of minute cells containing juices. When these juices
ferment, they lead to decay of timber. In the treatment process these juices are removed as
much as cells are filled with some preserving solution. The preserving solutions may be oil or
some salt solution.
The treatment processes can be categories:
1. Treatment by creosote oil
2. Treatment by salt solutions
3. Treatment heating under pressure
4. Painting
Treatment by Creosote Oil
It is also known as creosoting. In this process the railway sleepers are placed in a cylinder of
about 90" length and 6" diameter and are heated upto 175oF. A vacuum juices, afterwards,
creosote oil can be applied in two ways:
Full cell process In this process without destroying the vacuum, creosote oil is pumped into the
cylinder at a pressure of 75-150psi. all the cells are thus filled with the oil thus giving the name

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full cell process to the treatment. About 10-15 lbs of oil per cubic foot is required in this
process.
Empty cell process in this process, air is first forced into the cells followed by oil under pressure.
Less oil is used in this process. When the pressure is released some oil is forced out by the
entrapped air. In this method sleeper does not ooze oil. The railway sleepers treated with this
method are widely used in Pakistan. It resists the vermin and decay attack throughout its life
and the life is considerably increased.
Treatment by Salt Solution
In this process not pressure is employed but a sleeper is soaked in the salt solution over a long
period two types of salts are generally used i.e. Zinc Chloride. The process is called burnetising
process if the former salt solution is used and is called kyanisizing process if the later salt
solution is used.
The salt solution treated railway sleepers are cheaper and does not require expensive plants
but the solutions are likely to be washed away from sleepers by rain water. Moreover the salts
are poisonous and have greater danger towards labor handling them.
Heating under Pressure
In this process sleepers are subjected to high temperatures and pressures. The natural juices
are rendered harmless by this method.
Painting
Sometimes untreated sleepers are painted. It pressures timber by preventing the entrance of
moisture into the wood as long as the paint is intact. The ends should not be painted as it leads
to decay known as dry rot. It is not an efficient process of treating sleepers.

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Chapter No 05
RAIL CREEP
Creep in rail is defined as the longitudinal movement of the rails in the track in the direction of
motion of locomotives. Creep is common to all railways and its value varies from almost
nothing to about 6 inches or 16 cm.
Causes of Creep
The causes of rail creep can be broadly classified into two categories
 Major Causes o Creep,  Minor Causes of Creep.
Major Causes of Creep: Major causes of creep also known as principal causes of creep. Follows
are the major causes of creep in rail
1. Creep may be developed due to forces that come into operation when the train is starting
or stopping by application of brakes. Increase of starting the wheels pushes the rail backward
and hence the direction of creep is in backward direction.
When brakes are applied then the wheels of the vehicles push the rails in forward direction and
hence the creep is in forward direction.
2. Creep is also developed due to wave motions. When the wheels of the vehicles strikes the
crests, creep is developed.
3. Another reason creep develops because of unequal expansion and contraction owing to
change in temperature.
Minor Causes Creep: Some of the minor causes of creep in rail are below:

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 Rails not properly fixed to sleepers,  Bad drainage of ballast,  Bad quality of sleepers used,
 Improper consolidation of formation bed,  Gauge fixed too tight or too slack,  Rails fixed too
tight to carry the traffic,  Incorrect adjustment of super elevation on outer rails at curves,
 Incorrect allowance for rails expansion,  Rail joints maintained in bad condition.
Magnitude and Direction of Creep: Creep is not constant over a given period, it is not continue
in one direction or at uniform rate. Both the rails of the track may creep in same direction,
perhaps both the rails reverse the direction of creep or one rail creep in opposite direction to
that of other. In other words, the direction and magnitude of creep cannot be predicted.
Following are some of the items governing the direction and magnitude of creep
1. Alignment of Track: Creep is found to be greater on curves than on straights.
2. Grade of Track: Rails normally creep in the direction of downgrade through the creep in
reverse direction i.e. upgrade is also possible.
3. Direction of Heavy Traffic: If heavy or loaded vehicles run in one direction and the empty
train move in opposite direction then the creep is founded to be in the direction of loaded
trains.
Results and Consequences of Creep: Following are some of the undesirable consequences of
creep:  The most serious effect of creep is the buckling of track in lateral directions. If
unattended and not properly removed then it causes derailments which leads to accidents.
 Sleepers do not remain at fixed position and then gauges of the track are disturbed. The
alignment and rail level is also disturbed. This causes bad running of trains.  It becomes
difficult to fix the rails with creep. It is found either too short or too long due to creep.  The
gaps are widened at some places while closer at some places. This causes undue stresses.  The
location of points and crossings is disturbed and it is difficult to keep correct gauge and the
alignment.  The interlocking mechanism is also disturbed due to creep in rails.
Methods for Correction of Creep:
There are two methods used for the correction of creep. These are:
 Pulling back Method,  Use of Creep Anchors / Anti Creepers.
1. Pulling Back Method: In pulling back method the effects of creep are observed during
ordinary maintenance of track. Then the rails are pulled back equal to the amount of creep,
either by manpower or by the use of jacks. For this purpose, the sleeper fittings are made loose,
the fish bolts at one end of the rail are removed while at the other end they are made loose.
The liner of required size is interested in the gap and the rails are pushed or pulled as required.
Pushing is done by inserting short length of rod through bolt hole and then pushing the rail
forward by means of a crow bar. Pulling is done by inserting hook through the bolt hole and
then hauling the bolt hole by means of a rope attained to it.
Following points should be kept in mind in correction of creep:
 The track below sleepers should be properly packed after pulling and pushing operations.
 The small pieces of rails should always be kept ready during progress of work to allow passage
of trains at low restricted speeds.  The number of labours required depend upon the nature of
creep, number of sleepers affected due to creep.  All the fish bolts should be removed,
cleaned and oiled and then refixed and tightened up after the rails are brought to their proper

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positions by pushing or pulling.  The anchors, if to be installed, should be fixed after this
process.
2. Use of Creep Anchors OR Anti Creepers: In this method, specially constructed device known
as creep anchors or anti creepers are used. It consists of cast iron pieces used to grip the rails.
Creep anchors are provided behind the sleepers for every third or fourth sleepers.
This arrangement prevents the movement of rails because the sleepers which are embedded in
the ballast will also have to move if the creep has to take place. This method of reducing creep
is quite efficient and economical as it reduces the cost to the extent of about 75% to that of
pulling back method.
Various types and makes of patented creep anchors have been constructed and are in use and
most of them are found considerably effective.
The following points should be kept in mind in case of creep anchors:
 The creep anchors should be strong enough to resist the stresses produced due to creep.
 The number of creep anchors per rail length should be determined by intensity of creep.
 The creep anchors should be provided at a place where creep originates and not alone where
the results of creep anchors are most apparent.  It should be remembered that the creep
anchors should not be provided over railway bridges as far as possible.  It is better to provide
sufficient number of creep anchors to arrest the creep before it reaches a bridge.OR
Remedies of creep:
1. Pulling back the rails: pull back the rail to its original position. By means of
crow bars and hooks provided through the fish bolts wholes of rails.
By considering the position of joints relative to sleepers and both rails should be in respective
position.
2. Provision of anchors : By use of anchors and sufficient crib ballast. For creep 7.5 cm-15 cm 4
anchors per rail. For creep 22.5 to 25 cm 6 anchors.
3. Use of steel sleepers: Sleepers should be made up of good material with proper fitting.
Sleepers should provide good grip with ballast to resist the movement of sleepers. Increase in
no. of sleepers.
Site Selection for Railway Station
The following factors are considered when selecting a site for a railway station.
A railway station is that place on a railway line where traffic is booked and dealt with and
where trains are given the authority to proceed forward. Sometimes only one of these
functions is carried out at a station and accordingly it is classified as a flag station or a block
station. In the case of a flag station, there are arrangements for dealing with traffic but none for
controlling the movement of the trains. In the case of a block station, a train cannot proceed
further without obtaining permission from the next station and traffic may or may not be dealt
with. However, most railway stations perform both the functions indicated above.
supply is available for passengers and operational needs.
A railway station is defined as any place on a railway line where traffic is booked and dealt with
and where an authority to proceed is given to the trains. Following factors should be
considered while site selection for railway station:
Selection of Site for a Railway Station

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The following factors are considered when selecting a site for a railway station.
Adequate land: There should be adequate land available for the station building, not only for
the proposed line but also for any future expansion. The proposed area should also be without
any religious buildings.
Level area with good drainage: The proposed site should preferably be on a fairly level ground
with good drainage arrangements. It should be possible to provide the maximum permissible
gradient in the yard. In India, the maximum permissible gradient adopted is 1 in 400, but a
gradient of 1 in 1000 is desirable.
Alignment: The station site should preferably have a straight alignment so that the various
signals are clearly visible. The proximity of the station site to a curve presents a number of
operational problems.
Easy accessibility: The station site should be easily accessible. The site should be near villages
and towns. Nearby villages should be connected to the station by means of approach roads for
the convenience of passengers.
Water supply arrangement: When selecting the site, it should be verified that adequate water
1. Drainage: The proposed railway station site should be on a fairly leveled ground and it should
be well drained.
2. Water Supply: There should be plentiful supply for water at the site of station.
3. Future Allowances: There should be sufficient land available for the purpose of future
extensions along both sides
4. Gradient: The site should be such that permissible maximum gradients can be obtained
without much difficulty. The vehicles may start moving with wind which is very hazardous.
5. Location or Horizontal Alignment: The location of station yards should be such that it is
neither located near a curve nor on a curve.
6. Vertical Alignment: The train should not be situated in a sag but it should be on a summit.
7. Accessibility: The station yards should be such that it is easily accessible from city or town.
There should be well developed and efficient transportation system which leads the people and
their goods to station with much ease.
8. Visibility: The environment around the site selected for a station should be such that their
exists clear and improved visibility for the drivers of trains. There should be certain enough
arrangements made which improvements made which improves the visibility of a station.
9. Facilities: The site selected for the station should be such that for the passengers of trains,
machinery works, garages, workshops etc.
Soil Stabilization and Railway Track
Sometimes it becomes unavoidable to lay tracks on a very poor (or undesirable) soil. In such
cases it becomes necessary to improve and strengthen the nature of soil by some suitable
methods. Under such circumstances, the following methods are used.
 Layer of Moorum,  Cement Grouting,  Sand Piles,  Use of Chemicals.
1. Layer of Moorum: This method is widely used and is adopted if a poor quality soil comes
across a track such as black cotton soil which is a fine black loomy soil. This soil has the
tendency of expanding (or swelling) when moist and of caking and cracking heavily when dry.

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Tracks laid on formation of maintain. In rainy season, the soil fills up ballast interest less, the
track in the worst places gets sodden and spongy track is reduced. In hot weather, the cracks
are formed and the ballast is lost in filling up these cracks. Thus, the alignment as well as level is
disturbed and with mud filling the interstices, the track loses. Its resiliency, therefore, for these
very reasons, a layer of moorum varying in thickness from 12" to 24" is laid under the ballast.
This layer distributes the pressure of the load and prevents the ballast from being lost in the
cracks of the soil. Instead of moorum, other materials such as ashes, concrete, slabs, rubber,
unserviceable sleepers etc are also used and are found quite satisfactorily.
2. Cement Grouting: In this method, steel tubes of 1 1/4 " in diameter and 5ft long are driven
into the formation at every alternate sleeper and near their ends as shown in figure. The tubes
are driven into the foundation at an angle such that the end of tube is nearly under the rail. The
cement grout is forced under a pressure of 100 psi through these tubes. The proportion of
cement grout depends on the type and condition of formation. The concert grout spreads
through the poor soil and consolidates it. The steel tubes are then gradually taken out.
3. Sand Piles: This method of strengthening the track laid on poor is most widely used in
development countries like America. In this method, a vertical bore about 12" diameter is made
in the ground by driving a wooden pile. The wooden pile is then withdrawn and the space is
filled with sand and is well rammed. The sand piles are driven in the pattern as shown.
It is also arranged that cross sectional area of the sand piles is about 20% of the formation area.
Thus, the top section of the formation is covered with sand which makes the track stable on
poor soil.
4. Use of Chemicals: In this method, chemicals are used in place of cement grout to consolidate
the soil. For example, silicate of soda followed by calcium chloride is effective for sandy soils
containing less than 25% of silt and clay.
What is the main factor affecting the landing strip length of airplanes?
To begin with, pilots tent to choose airports with enough runway length for the aircraft to land
without much concern. That’s not necessarily true for “Bush Planes” that operate from off
airport terrain.
The typical things that pilots consider are:
 The type of aircraft. Some aircraft are designed to land at slower airspeeds and some
faster airspeeds. That helps determine the required runway lengths.
 The aircraft’s landing weight. The heavier the aircraft the longer the required runway.
 The aircraft’s approach speed. The faster the approach speed, the longer the required
runway.
 The aircraft’s flap setting. Landing with full flaps vs less than full flaps shortens the
required runway.
 The aircraft’s use of speed brakes or engine reversing capability. If the aircraft has
these capabilities, then less runway is required.
 The airport/runway MSL altitude. The higher the runway is above sea level, the longer
the required runway.
 The airport/runway Outside Air Temperature / Pressure Altitude. Hotter than
standard temperatures will make any runway seem like it’s higher than it actually is
and that requires longer runways.

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 Headwind component. The more headwind component the shorter the required
runway.
 Runway Slope. Landing uphill means a shorter runway and vice versa.
 Surface type. Smooth concrete requires more runway than grass, for example.
Pilots take all of this into account when planning landings, especially at runways that are
considered shorter.
Track Fittings and Fastenings
Track fittings and rail fastenings are used to keep the rails in the proper position and to set the
points and crossings properly. They link the rails endwise and fix the rails either on chairs fixed
to sleepers or directly on to the sleepers. The important fittings commonly used are:
1. Fish plates, 2. Spikes, 3. Bolts, 4. Chairs, 5. Blocks, 6. Keys, 7. Plates.
Pandrol clip or elastic rail clip: The Pandrol PR 401 clip is standard type of fastening used in
I.R.(Indian Railway). • Earlier manufactured by Messrs and Guest, Keens and Williams.
• Require very less maintenance. • Spring steel bar with a dia of 20.6 mm and is heat treated.
• It exerts a toe load of 710 kg for a nominal deflection of 11.4 mm. • Can be fitted to wooden,
steel, cast iron and concrete sleepers. • Disadvantage is that it can be taken out using ordinary
hammer so does not provide enough safeguard.
Fish plates: These are used in rail joints to maintain the continuity of the rails and to allow
expansion and contraction.
Requirements of fish plates: Fish plates should maintain the correct alignment both
horizontally and vertically. • They should support the underside of the rail and top of the foot.
• Provide proper space for the expansion and contraction. • They should be made up of such a
section to withstand shocks and heavy stresses due to lateral and vertical B.M
Sections of fish plates: Various sections have been designed to bear the stresses due to lateral
vertical bending. Standard section is bone shaped. Design of fish plate section is depends up on
the various stresses due to lateral and vertical bendings. The strength of fish plate can be
increased by means of increase in the depth but the c/s of fish plate is constant through out the
length. Ex: Bone shaped plate for F.F rails, Increased depth fish plate for B.H rail.
Spikes: For holding the rails to the wooden sleepers, spikes of various types are used.
Requirements of spikes: Spikes should be strong enough to hold the rail in position and it
should have enough resistance against motion to retain its original position. The spikes should
be deep for better holding power. It should be easy in fixing and removal from the sleepers.
The spikes should cheap in cost and it should capable of maintaining the gauge.
Various types of spikes:
1. Dog spikes: For holding F.F rail to wooden sleeper. These are stout nails to hold rail flanges
with timber sleepers. The only disadvantage of these spikes is that due to wave motion of rail
the spike is driven out of the sleepers which reduce the pressure on the foot of F.F rails,
resulting in creep occurrence.
2. Screw spikes: these are tapered screws with V threads used to fasten the rails with timber
sleepers. These are more stronger than dog spikes in holding power. These are costly and the
gauge maintenance is more difficult than earlier one.
3. Round spikes: The head shape is either cylindrical or hemi spherical. These are used for fixing
chairs of B.H. rails to wooden sleepers and also fixing slide chairs of points and crossing.

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4. Standard spikes: These are used for cast iron chairs only to fix them with timber sleepers.
5. Elastic spikes: The disadvantages of dog spikes can be eliminated by this. The advantages of
this spikes is its head absorbs the wave motion without getting loose.
Chairs: These are used for different types of rails C.I Chairs: For holding D.H and B.H rails, chairs
are used. B.H rails are supported on C.I Chairs fixed to the sleepers by round spikes.
Slide chairs: These are plates of special shape on which the stock and tongue rails rest.
Blocks: when two rails run very close as in case of check rails, etc. small blocks are inserted in
between the two rails and bolted to maintain the required distance.
Bolts: used for fixing various track components in position.
Dog or hook bolt: when sleepers rest directly on girder they are fastened to top flange top
flange of the girder by bolts called dog bolts.
Fish bolt: made up of medium or high carbon steel. For a 44.7 kg rail, a bolt of 2.5 cm. dia. and
12.7 cm length is used. With each fish plate standard practice is to use four bolts. Generally, a
projection of 6 mm of the shank is left out after the nut is tightened.
Keys: Keys are small tapered pieces of timber on steel to fix rails to chairs on metal sleepers.
Morgan key: This is about 18 cm long and tapered 1 in 32. these are suit the C.I chair, plate
sleepers and steel sleepers with the rail. The advantages of morgan keys are: • They can be
used as left hand or right hand keys. • They are light in weight due to double recess on either
side. • They are versatile in nature.
Bearing plates: Bearing plates are rectangular plates of mild steel or cast iron used below F.F
rails to distribute the load on larger area of timber sleeper.
Advantages: To distribute the load coming on rails to the sleepers over a larger area and to
prevent skidding of the rail in the soft wooden sleepers. • Prevent the destruction of the
sleeper due to rubbing action of the rail. • Adzing of sleeper can be avoided by bearing plates.

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