Transportation engineering lecture notes: -

Modes of transportation: - Human being has always remained surrounded by the

three basic mediums known as land, water and air. Thus the modes of

transportation are also connected with these three mediums. Land has given

scope for the development of road and rail transport while water and air have

developed waterways and airways respectively. Thus there are four different

modes of transportation as follows:

1. Road ways / highway

2. Railways

3. Airways

4. Waterways/ sea ways

1. Roadways/ highways: It is the basic mode of transportation and the only

mode which give door to door service to people and goods. It plays a very

important role in the development of economy of the country. Basic need

of roads arose thousands years back when only earthen roads were used

for transportation only. They only increase time of the journey but also

affects the comfort of the passengers and also their safety, beside the life

of earthen roads was never consistent because of these problems, the

concept of firm roads were develop which later on took the shape of

bitumen or concrete road. Roadways do not only increase the modern

highway system but also the city streets, feeder road and village roads.

Every highway can be a road but every road can’t be highway.

2. Railways: - After highway it is the second most common mode of

transportation and it is considered to be cheapest mode among all the

movement of equal and good load is possible because of railways. It is very

useful when you are travelling long distances within a country or from one

country to another country. Another important advantage of railway is that

if the system is manage properly there is no disturbance in the movement

of train which save a lot of time and other resources, also because of

railway lines are fixed the chances of accidents are minimum because the

trains have only to move on the railway line.

3. Airways: - In old times when air ways were not yet develop; the time of

travelling was normally very high especially when you move from one

country to another country because of the lesser speed of vehicles and

several obstructions like seas and oceans from a mountain, from protocol

of different countries etc. Therefore with the development of aero plane,

the distances were reduced to a great extent because of the higher speed

of aero plane and also because it could by pass any type of obstruction.

Besides saving time, it has got relative amount of safety due to the

fixed routes, heights and timings of the aero plane but whenever the accidents

occurs the chances of survival are minimum. Its major drawback is that it can only

be used by elide class of the people.

4. Seaways: - Seaways are broadly classified into two types as:

(a) Inland waterways

(b) Docks, harbours and ports

(a) Inland waterways: - Inland waterways were mainly used in accidents times

for the movement of people when other modes of transportation were not

yet developed. They were used whenever seas, rivers or any other form of

water channel was available. Nowadays it is rarely used because of the long

time it takes in order to reach from one place to another. Mostly people

use it for recreation purpose.

(b) Docks, harbours and ports: - On the other hand docks, harbours and ports

are extensively used for the transportation of heavy machinery and huge

quantity of goods and cargo from one country to another having

developed. Ports and harbours can not only fulfils their requirements but

also can earn huge amount revenue by transportation the goods of other

neighboring land locked countries. The biggest advantage of docks and

harbours is that the material at a cheaper cost besides taking proper

measures the safety of this mode can be ensured.

Minor modes of transportation: - Apart from these four systems of

transportation some other minor modes used are

(a) Pipeline

(b) Cables, ropes and elevators

(a) Pipeline: - Pipelines are used for the transportation of liquids and gases

from the source of generation to the houses and other commercial places.

(b) Cables, ropes and elevators: - This mode of transportation is used for

mainly for small groups or parts of buildings just like in a mountainous

region when you have to reach from one place to another and no road is

available. Cables are used to carry people while in multipurpose buildings

elevators are used in order to carry people from one story to another story

of the building.

Need and scope of comprehensive plan: - Following points should be kept in

mind in order to prepare a comprehensive plan for the transportation plan:

1. Straight route

2. Early grades and curves

3. Availability of land

4. Availability of material

5. Geometric design

1. Straight route: - The road, highway and railway should be aligning as

straight as possible because the construction cost is greatly decreased if the

road is constructed as straight as possible. Straight route also makes the

journey of the passengers easy and comfortable which is one of the major

prerequisite of any transportation system. Also from safety point of view

straight route is considered to be the best as chances of accidents are

minimum if you follow the rules of traffic. Another important aspect of the

keeping the route straight is to ensure less wear and tear on vehicles,

hence increasing the life of the vehicles.

2. Easy grades and curves: - Another important point of planning of transport

system is provision of easy gradients and proper curves by providing them

comfort and safety of the journey and also the vehicle life can be

maximized just like it is essential to avoid curves as much as possible and it

becomes absolutely necessary then transition curves should be provided

because the change in duration is gradual in it. In the same way proper

filling and cutting is done in order to have easy gradients along the routes

besides blasting is also done in mountainous region to prepare proper

gradients.

3. Availability of land: - Another important point to prepare a comprehensive

plan is to make sure that adequate land is available for the construction of

our proposed transportation system. Availability of land mainly indicates

that after acquiring the land, the proposed alignment should be free from

any type of dispute. It also indicates that enough space is also spread for

the future development. This rarely is one important aspect of planning

because the needs in the future will surely increase and the transportation

system will ultimately fail if the adequate land is not acquired.

4. Availability of material: - The cost of project greatly depends on the easy

and cheap access to the materials therefore in the planning stage it is kept

in mind the near by resources of material and the proposed alignment can

be changed in order to have an easy access towards material as the

construction of any transportation system highways, railways etc involve a

lot of money therefore this factor is also consider very important.

5. Geometric design: - In the planning phase it is also very important to have

proper design of the road so the life of road could be maximized certain

features which come under design are various site distances, thickness of

road and all its layers, design of embankments, design of bridges, flyovers

under passes, drainage consideration, camber, super elevations etc. All

these factors are important too much to be properly design in order to

have a safe movement of vehicles and also for the durability of the road.

Sites for bridges and tunnels: - In the construction of tunnels and bridges it is

always kept in mind that the access to the machinery and material is easy and

safe and it is also kept in mind such a site should be selected where cost is

minimum for this purpose the whole region along the proposed route is surveyed

and determine that which particular route has minimum distances for the

construction of tunnels and bridges it would greatly affect the cost of bridges and

tunnels. Similarly care should be taken in order to finalize the site for bridge so

that access to materials and machinery is safe and easy.

Free from frost and rain: - It is important to select or finalize the route according

to various weather conditions like as much as possible areas of resistant, snowfall

and rain fall should be avoided in order to increase the road life as well as safety

of the journey, therefore while finalizing the alignment such areas should by pass

and the route finalized should be made free from frost and rain.

Principles of planning: - Following points should be kept in mind while planning a

new transportation system:

A transportation system should provide a safe, efficient, comfortable,

speedy movement of people and goods.

There should be adequate amount of funds available for construction of the

transportation system because if the funds are not available then not only

the quantity of work compromised but also huge financial losses will be

suffered.

Future expansion should be kept in mind while planning a new

transportation system, therefore adequate amount of length should be

reserved and continuous monitoring should be done so that any illegal

settlement and encroachment take place. Foe that purpose trained people

or population growth and increased in the movement of vehicles moving

per year should be determined.

Available resources should be utilized up to a maximum benefit so as to

save the economy of the project.

A basic principle of planning a new transportation system is to give

maximum utility to the people.

A transportation system should be planned in such a way that it contributes

the development of the area.

Maintenance is also an important factor because transportation system

gets deteriorated if proper maintenance is not done with passage of time.

Therefore availability of funds and labors should be kept in mind for the

maintenance purpose.

Although principle of planning is to ensure the safety of passengers and

vehicles for that purpose detail traffic study should be carried out and the

network should be designed properly.

Phases of planning:

1. Economy: - The first phase of planning is the economy of project and when

we talk about the economy the first thing that comes in mind is how much

the purposed transportation system will benefit the people of that area.

For this purpose a detail survey is carried out to see how many towns,

villages and localities and cities are along the purposed alignment beside

that past train of bucklation growth are studied and future trains are

estimated. According to that transportation system is planned. Another

important thing in the economy is the development of industrial and

agricultural sectors of the area because with the construction of a new

road, railway, port or harbour will definitely facilitate the development of

the area and the country. Existing facilities are studied to see whether it is

important to enhance them or kept them at their level.

2. Finance: - After the economy is studied the second phase of planning is

finance, which actually indicates how much funds are available for the

construction of the transportation system. The funds could be in the shape

of funds generated by NGO or by international NGO donor agency, funds

donated by wealthy people with and outside the country. Estimating all

those funds and rough cost of project, affezibiliy report is prepared beside

that after the completion of the project how much revenue could be

generated from vehicle registration, different types of taxes, construction

along the highway etc are also estimated in the finance phase another

important thing is the allocation of funds for the maintenance purpose.

3. Survey: - Once a purposed project is considered feasible then the next

phase is survey. There are very stages of surveying starting with map study,

which could easily be carried out in the office and root could be purposed

after which reconnaissance is done and thing which are not mentioned in

the map are noted and slight adjacements could be made in the purposed

root after wards preliminary survey is carried out with the help of minor

instruments it gives you some more detail of the area after detail survey is

done in order to fix the alignment of the road.

4. Design: - Once a report I finalized various components of the transportation

system are design and construction becomes easy. Generally the things

which are design can be thickness of various layers of a road or highway,

the estimated vehicle load, design of pre stress bridges and tunnels,

different site distances, curves and super elevations, camber, embankment,

shoulders etc.

Railway track: -

The railway track is a structure consisting of parallel lines of rails with their

sleepers, fittings and fastenings, ballast etc to provide a road for the movement of

locomotive or coaches.

Or

Railway track is also known as permanent way. The name of permanent way is

given to the track to distinguish the final track constructed for the movements of

trains from the temporary track laid for transporting the construction materials

such as sleepers, rails, ballast etc.

The track is the rail road on which two trains run. Basically a track consists

of two parallel rails having a specified distance between them known as

gauge and fastened to the sleepers. These sleepers are embedded in a layer

of ballast of specified thickness spread over the formation. The rails are

joined to each other by fish plates and bolts and the rails are fastened to

the sleepers with the help of various fittings such as spikes and keys. The

sleepers are spaced at a specified distance and are held in position by

embedding in ballast.

Methods of Construction of railway track: -

1. Old method 2. Modern method

1. Old method: - In this method the construction work was done with the help

of labor. Mostly the machinery was not used for the transportation of

passengers and goods.

2. Modern method: - In this method the work of construction is done with the

help of machines and modern techniques and equipments are used for

construction.

Steps for construction of railway track (old method)

1. Planning: - In this initial stage we discuss the following points:-

Route of track

Advantages of track

Disadvantages of track

Contractor details

Budget

2. Survey: - In the survey we collect the data about the following points: -

Soil

Routes advantages and disadvantages

Best position of station and yards

Best track type

Best route

3. Designing: - in designing a designer finalize the following points: -

Route of track

Length of track

No of tracks

Position of stations

Type of gauge

Width of formation

Depth of ballast

Type of material which is used in construction

Every detail about the field work will be given in designing

Requirements of an ideal track: A good track should provide comfortable and

safe journey at the maximum permissible speed with minimum maintenance cost.

To achieve these objectives the track should meet the following requirements.

o The gauge of the track should be correct and uniform.

o The alignment of the track should be correct having no kinks or

irregularities.

o In straight portion of the track whenever a curve is required transition

curve should be provided which should be as straight as possible.

o Super elevation should be provided on the curve portion of the track to

sustain the effects of the centrifugal force.

o The gradients should be uniform and as gentle as possible. The change of

gradients should be followed by a vertical curve to give smooth ride.

o In order to absorb shocks and vibrations of the moving train the track

should resilient and elastic.

o The drainage system of the track should be perfect so that stability of the

track is not affected by water logging or drainage water.

o The track should be design in such a way that the load of the train should

be distributed uniformly.

o The friction between the wheels of the locomotives and the rails should be

minimum so as to avoid extra heat which could generate fire.

o Adequate provision of repair and replacement and renewal of damaged

portion should be provided.

o The track should possess high resistance to damage at the time of

derailment.

o The track should be stiff and tough in order to sustain variation in

temperature, centrifugal force and lateral trust.

o Joints, points and crossings should be designed and maintain properly.

o The track should possess antitheft and sabotage qualities.

o The track structure should be such that initial and maintenance cost is

minimum.

Components of railway track: - The track or permanent way is consisted of the

following components:

(a) Formation

(b) Sleepers

(c) Rails

(d) Ballast

(e) Fittings and fastenings

(a) Formation: - Formation is the base or foundation of the railway track. It

gives a surface where ballast rests. It takes the total load of track and the

trains moving over it. It is prepared over various layers and is of highly

importance for a proper railway track.

OR

The formation is the surface on which the track (including ballast) is laid.

Traditionally, it was the finished surface of the earthworks. It includes sub grades

and earth work and sub ballast.

Purpose of track formation: -

To make regular bed to put the ballast section.

To support the load coming for ballast and train.

To provide good drainage

Steps for construction of track foundation: -

Preparing of natural ground surface by releasing of trees.

Adding a layer of soil of 15-20cm.

Compaction of layers according to the type of soil.

The soil of good properties to be put at the top and slopes while the soil of

low properties to be put at the middle.

It must be compact well for the surface soil and gently finished without any

excavation to prevent bad drainage.

Disadvantages of track foundation: -

Unstable foundation leads to increasing of maintenance cost

Low speed of train

May cause accidents

May find soft spots filled with water which are at last caused sliding or

failure

These spots increase by increasing the movement

Sliding will happen as a result of rain. It is dangerous type of unstable soil.

Treatment of track foundation: -

Drainage of water must be away from the track

Bitumen coating should prevent the soil from water table

Releasing of trees by burning, mechanically or manually and chemically

Chemical materials to be mixed with soil to improve its properties

(b) Sleepers: - The sleepers hold the rail together in proper position and help in

providing and maintaining a proper gauge with the help of fittings and

fastenings. Besides it also transfer the load of the locomotives to the ballast

below.

Or

Railway sleeper is a rectangular support for the rails in railway tracks. Generally

laid perpendicular to the rails, ties transfer loads to the track ballast and sub

grades, hold the rails upright, keep them spaced to the correct gauge.

Purposes of sleeper: -

Keeping of rails at constant distance.

Insure elastic layer between the rail and the ballast section.

Distribute and transfer the load on layer area of the ballast section.

To resist the extension of rail due to change of temperature

Placing of sleepers: -

After the ballast section the sleepers are placed at suitable locations. 1st

alignment is also made before fixing of rails. Sleepers placed should be :

According to design

Same level

Uniform size

© Rails: - Rails are the steel girders over which train or locomotive moves and

transfer the wheel load of train to the sleepers below. After the placing of

sleepers rails are fixed on the sleepers.

Or

Rails are steel girders over which the train moves and give smooth

movement to the wheels of the locomotives. It also transmits the wheel

load to the sleepers below.

Function of rails: - Following are the function of rails:

The rails distribute heavy load of the locomotives, their wheels, axels,

goods and passengers over a large area of formation through sleepers and

ballast.

The rails provide a level and continuous surface for the smooth movement

of the trains.

The rails bear the stresses developed due to vertical loads transmitted to it

through axles and wheels of the rolling stock due to breaking forces and

thermal stresses etc.

The rails serve as a lateral guide for the running of wheels.

The pathway of a railway track has a very less friction which is about 20% of

the friction of the normal road making it safer for the movements of the

rails.

Types of rails: - Rails can be classified into the following three categories:

1. Double headed rail

2. Bull headed rail

3. Flat footed rail

1. Double headed rail: - Originally the rails used were double headed made of

I-section or dumb bell section. The idea behind the developing this type of

rail was that once the top head was worn out, during its service life the rail

could be inverted and reused without any further expenditure. Such rails

have to be supported on chairs which rest on sleepers. But later it was

found that during continuous movement of trains after the service life of

the top head was over the head had already been dented and could not be

reused.

2. Bull headed rail: - It was almost similar to the double headed rail the only

difference being more amount of metal used in the head of the bull headed

rail allow greater wear and tear. This rail also require chairs for fixings it to

the sleeper which proved to be greater drawback.

3. Flat footed rail: - To remove the drawback of other two types of rails

Charles Vignoles developed an inverted T-Shaped section known as flat

footed rail in 1836. It is also known as Vignole rail.

Advantages of flat footed rails:

For fixing the sleepers in flat footed rails no chairs are needed.

For the same weight, the rail is stronger vertically and laterally better

than bull headed rails.

It is cheaper than bull headed rails.

It requires less fastenings than bull headed rails.

Flat footed rails give stability to the track as these rails distribute rolling

stock load over number of sleepers.

Flat footed rails develop fewer kinks and maintain a more regular top

surface than bull headed rails.

Flat footed rails give longer life to the track and reduce maintenance

cost.

Flat footed rails have been widely accepted through out the world.

Requirements of an ideal rail section: - Following are the requirements of an

ideal rail section:

The rail should possess adequate lateral and vertical stiffness.

The shape of the bottom of the head and top of the foot should be such

that fish plates could be fixed easily.

The depth of the rail head should be sufficient margin for the vertical wear.

The rail should be shaped suitably.

The metal distribution in head, web and foot of the rail should be properly

balanced.

The surfaces and gauge faces should be hard and capable to resist water.

The width of the foot of the rail should be sufficient to spread the rolling

stock load in a larger area of the sleeper.

The centre of the gravity of the rail section should be located very near the

centre of the height of the rail so that maximum compressive and tensile

stresses are equal.

The contact area between the rail and wheel should be sufficient to

minimize the contact spaces.

Generally we can say that the rail should have economical section

consistent with strength, stiffness and durability.

Points of comparison between double headed and bull headed rails with flat

footed rail: -

Comparison points Double headed and bull headed rails

Flat footed rails

Initial cost These require more cost fastening so their initial cost is more.

These rails require less and cheaper fastenings so their initial cost is less.

Strength and stiffness These rails have less strength and stiffness.

These rails have more strength and stiffness.

Rigid These rails are less rigid. These rails are more rigid.

Arrangements Arrangements at these places are complicated.

These arrangements are simple.

Maintenance These rails require heavy maintenance.

These rails require less maintenance.

Suitability These rails are more suitable for tracks when lateral loads are important than vertical load.

These rails are more suitable due to more strength, stiffness and better stability and economy.

Rail gauges: - The gauge is defined as the minimum distance between the running

inner faces of the rail. In some countries gauge measured between the runnings

faces of the rails. Due to historical consideration gauges have been adopted on

the railways in the world. Actually it is very difficult to spell out the reasons for

adopting different gauges in different countries.

Factors affecting the choice of the gauge: - Practically it is quite impossible to a

particular type of gauge because whatever type of locomotives is available in the

country. The gauge has to be according to its size but incase of the future

planning following features or factors are kept in while choosing a type of gauge:

1. Traffic consideration

2. Cost consideration

3. Physical features

4. Development of poor areas

5. Speed of movement

6. Cost of the track

7. Uniformity of gauge

Defects of rail: - Due to the continuous loading of the locomotives, abrasive

forces, temperature changes, quality and alignment of the track, friction etc may

cost various types of defects in rail which ultimately leads to the repair or

replacement of the rail. Out of these effects wear is considered to be a major one

which is actually changes in the dimensions of the rail.

Wear of the rail can be classified into three categories:

(a) Rail wear on head

(b) Rail end batter or wear at the end of the rail

(c) Wear on the sides of the rail

(a) Rail wear on head or rail wear on the top: - Due to the impact of different

types of forces coming on the top of the rail. The rail top flows and assumes

the shape like forming projections on the side. These projections beyond

the original section of the rail are known as burns.

Cause of wear development on the top of a rail: - Following are the causes for

the development of wear on the top of a rail:

The main factor or cause of rail wear of head is movement of heavy loads of

the locomotives over a small area of rail resulting in high amount of

stresses which exerted the elastic limit and produces wear.

The head of the rail worn out due to abrasion forces of the wheels.

The grinding action of sand particles between the wheels and rail also help

to produce wear of a rail.

Corrosion of rail also helps in the wear of top of a rail.

Measurement of wear: The wear on rails can be measured by any of the

following methods:

By weighing the rail

By profiling the rail section with the help of lead strips and needles

By specific instruments designed to measure profile of rail and to record it

simultaneously on the graph paper

(b) Rail end batter or wear at the end of a rail: - The hammering action of

moving loads at the rail joints cause the rail end batter in course of time.

We can say that at the end of the rail if there is slight change in the height

of the rail it means the rail has gone worn out at the end.

It is measured as the difference between the vertical height of rail and at a

point 30 cm away from the end. If the batter is up to 2mm it is considered as

average or tolerable bit if it exceeds 2mm it is considered to be serve and

needs to be replaced or properly repaired.

Effects of end wear of a rail: - Due to the hammering action of moving loads at

the rail joints following side effects are produced:

The contact surfaces between the rails and sleepers get worn out.

Fish bolts and fish plates become loose

Due to the vibrations at the joints the settlement of ballast takes place

resulting in depression of sleepers

These factors further worsen the situation by increasing the rail end batter

due to the following reasons:

Due to heavy loads and large joint openings

Due to poor maintenance of the track

Due to bad condition of vehicle springs

(c) Wear on the sides of a rail: - This is the most destructive type of wear and

occurs when the track is on the curves and dimensions of the rails from

outer as well as inner rail changes due to this wear.

Causes of wear on the side of a rail: - It is caused by following reasons:

On the curve portion of the track, the centrifugal force causes thrust of the

wheel flanges against the side of the outer rail head which results in the

grinding of the rail flanges producing side wear on the outer rail.

Unlike the road vehicles the trains do not bent to the shape of the

curvature resulting in the biting of the inner rail of the outer rail by wheel

flanges due to the rigidity of wheel base.

Wear also takes place on the inner rail on a curved section due to the

skidding and slipping action of the wheels on the curve.

Measures to minimize wear of rails: - Following measures could be taken to

minimize wear of the rails:

By conning of the wheels

By providing super elevation on the tracks

By the use of special alloy steel for rails

By adopting good maintenance of the track

Regular tightening of fish bolts and packing of ballast will reduce wear

By reducing number of joints and expansion gaps

When the wear exceeds 5 % of the total weight of the section the rail must

be replaced

By lubricating the gauge face of the outer rails

By adopting exchange of inner and outer rails

By introducing check rails on the curves

Creep: - Second major effect in the rail is creep which is longitudinal

movement of the rail in the direction of movement of locomotives. It could be

either in the forward direction and backward direction. Its values ranges from

the absolutely nothing to 6 inch.

Causes of the creep: - Following are the causes of the creep:

Application of brakes and applying acceleration to generate a lot of force

which may move the rail and cause creep. By the application of brakes

creep takes place in the forward direction and acceleration causes creep in

the backward direction.

Second major cause of creep is when the locomotives move on a track it

generate a wave action in the rails due to the elasticity of the track that

wave action would also generate creep.

The unequal contraction and expansion due to the various temperature

changes may also cause creep.

Minor causes of rail defects: Following are the minor causes of rail defects:

Improper fixing of rails with sleepers

Bad quality of sleepers used

Improper maintenance of the track and joints

Loosing of fittings and fastenings

Improper super elevation of curve portion

Bad drainage of the ballast

Inferior quality of rails used

Other minor causes of defects of rails:

1. Wheel burns: - Due to the acceleration and breaking activity high amount

of abrasive forces are generated which may cause a lot of heat and hence

wheel burns takes place which are docks spots on the rail and if not repair

in time will ultimately caused the parts of metals to flow which may causes

depression of the rail table and serve consequences may be witnessed.

2. Scabbing of the rails: - The scabbing of the rails is due to the falling off

patches of metal from the rail table. It is generally seen in the form of

depression and the surface shows fracture with numerous cracks around it.

3. Hogging of the rails: - The rails bent vertically at the ends are known as

hogged rails. The hogging of the rails is one of the serious defects which

develop due to poor maintenance of rail joints, yielding formation, loose

and faulty fastenings etc. it causes deterioration to the running quality of

the track. The hogged rails must be replaced or repair in time to avoid

derailment.

Sleepers: - Sleepers are transverse support to a railway track which provides

stiffness to it. It is used universally accepted throughout the world and were

introduced for the first time in 1835.

Railway sleeper is a rectangular support for the rails in railway tracks. Generally

laid perpendicular to the rails, ties transfer loads to the track ballast and sub

grades, hold the rails upright, keep them spaced to the correct gauge.

Purposes of sleeper: -

To hold the rails to correct gauge and alignment

To give a firm and even support to the rails

To provide proper grade, longitudinal and lateral stability to the track

To provide insulation for the electrified track

Keeping of rails at constant distance.

Insure elastic layer between the rail and the ballast section.

Distribute and transfer the load on layer area of the ballast section.

To resist the extension of rail due to change of temperature

To provide easy mean of replacement of rails without disturbing the whole

traffic

Placing of sleepers: -

After the ballast section the sleepers are placed at suitable locations. 1st

alignment is also made before fixing of rails. Sleepers placed should be:

According to design

Same level

Uniform size

Requirements of an ideal sleeper: - An ideal sleeper should meet the following

requirements:

The initial as well as maintenance cost should be minimum

The weight of the sleeper should be moderate so that it can be handled

easily so that gauge may be adjusted easily and maintained costly

It should be shock and vibration absorbent which developed due to passage

of fast moving trains

The design and material of the sleeper should be such that it may possible

to be used on a circular track

The sleeper should have sufficient bearing area

It should be antitheft and anti sabotage qualities

The sleeper should hold its position and not get disturbs by the moving

traffic

Sleeper density: - The number of sleeper used per rail length is known as sleeper

density. Generally one sleeper is used for every one meter length of the rail. It is

specified as N+x or M+x where N or M is the length of the rail and x is the

mathematical number which varies according to the following factors:

Axle load and speed of the train

Type and section of the rail

Type and strength of sleeper

Depth of ballast cushion

Nature of formation

Naturally in railways the sleeper density for broad gauge is N+7 where length of

the rail is normally 12 or 13 meter.

Classification of sleepers: - In railways mostly following four types of sleepers are

used. In other words sleepers can be divided in to the following four categories:

1. Wooden sleepers

2. Cast iron sleepers

3. Steel sleepers

4. Concrete sleepers

1. Wooden sleepers: - Wooden sleeper is the ideal type of sleeper hence they

are universally used. The utility of timber sleeper has not decreased due to

passage of time. However due to the low service life about 15 years and

high maintenance cost the use of wooden sleepers on main lines has been

completely stopped by the year 1999.

Advantages of wooden sleepers: - Wooden sleepers have the following

advantages:

They are cheap and easy to manufacture

They are ideal for track of circular section

They are more useful for heavy loads and high speed

They are easy to handle without damage

They absorb shocks and have good capacity to dampen the vibrations

They are more useful for yielding formation

Alignment can be corrected easily

They are more suitable for modern methods of maintenance

They can be used with or without stone ballast

They can be used on bridges

They can be used for gauntleted track also

Disadvantages of wooden sleepers: - Wooden sleepers have the following

disadvantages:

They are easily liable to attack by vermin and weather

Their service life is shorter than any other type of sleeper

It is difficult to maintain gauge with their use

They are susceptible to fire

Scrap value is negligible

Their maintenance cost is higher than any other type of sleeper

They are liable to mechanical wear

2. Steel sleepers: - The increasing shortage of good timber in the country and

other economical factors are mainly responsible for the use of steel

sleepers. About 27% of the track on railway is laid on steel sleepers

Advantages of steel sleepers: - Steel sleepers have the following advantages:

It is more durable

Its service life is about 50 years

It is easy to maintain gauge and lesser maintenance problems

It gives better lateral rigidity

Lesser damage during handling and transport

Its manufacturing process is easy

It is not susceptible to vermin attack and fire hazards

Its scrap value is very good

Disadvantages of steel sleepers: - - Steel sleepers have the following

disadvantages:

It is liable to corrosion

It is unsuitable for electrified tracks

Due to slopes at two ends it is liable to become centre bound

It require more fittings in numbers

More ballast is required than other types of sleepers

During service it develops cracks at rail seats

It can be used only for rails which it is manufactured

3. Cast iron sleepers: - They are used extensively all over the world at

present45% of the total tracks are being laid with cast iron sleepers.

Advantages of Cast iron sleepers: - Cast iron sleepers have the following

advantages:

They are easy to manufacture

They are lesser liable to cracks at rail seats

Their service life is up to 50 to 60 years

They provide high lateral and longitudinal stability to the tracks

They are lesser liable to corrosion

Their scrap value is very good

Disadvantages of Cast iron sleepers: - Cast iron sleepers have the following

advantages:

Gauge maintenance is difficult as tie bars get bent up

They are not suitable for electrified tracks

They need large number of fittings

They are more liable to breakage and damage if handled roughly

The rail seat wear out quickly resulting in loosening keys

Heavy intensities of traffic and greater speed more than 110 km/hour

will cause loosening of keys, packing and development of high creep etc

resulting in replacement of sleeper

The cantilever ends of rails are long which results in hogging of the rail

ends and deterioration of ballast under the joint which results in the

replacement of sleeper

4. Concrete sleepers: - The development of the concrete sleeper took place in

the year 1877 due to shortage of timber but most of the work was carried

out on it after the World War II.

Advantages of Concrete sleepers: - Concrete sleepers have the following

advantages:

Concrete sleeper being very heavy give more elastic modulus, strength

and stability to the track

They are specially suitable for long welded rail track due to great

resistance to the buckling of the track

Concrete sleepers with elastic fastenings maintain better gauge, cross

level and alignment. It also retain very well.

Concrete sleepers can also be used in tracks circulated areas as concrete

is poor conductor of elasticity

Concrete sleepers neither are susceptible to attack by vermin nor they

are to corrosion

They are susceptible to fire hazards

The service of concrete is very long about 50 to 60 years

Concrete sleepers can be manufactured from local material also

Disadvantages of Concrete sleepers: - Concrete sleepers have the following

disadvantages:

Being heavy their handling and lying is very difficult and costly.

Mechanical devices have to be used which involve heavy expenditure

At the time of derailment of the concrete sleepers are damaged heavily

There is no scrap value of the concrete sleeper

The concrete sleepers should be maintained by heavy “ON TRACK”

tampers

Rail joints: - A rail joint is the weakest part of the track. In order to provide

provision for expansion and contraction of rails due to variation in temperature

certain gap is provided at each joint. This gap cause breaks in continuity of rails

forming the weakest part of the track. This gap also causes serve blows to the

passengers due to the moving of wheels over this gap. It also loose in compaction

of ballast under the sleeper bed and make the maintenance of joints difficult. It

also causes loosing of fittings and fastenings therefore it is very important to

regular maintenance the rail joints.

Requirements of an ideal rail joints: - An ideal rail joint should possess the

following characteristics:

The rail joint should be capable of holding the two ends of rails as near as

possible

The rails on both parts at the joints should be at a same level and in a

straight line

An ideal rail joint should have the same strength and stiffness as the rails

which have been joined together

The rail joint should provide space for expansion and contraction due to the

variation in temperature

The initial cost of the joint and its maintenance should be minimum

The joint should be such that any rail could be replaced without disturbing

the whole track

Types of rail joints: - Depending upon the position of joints and sleepers rail joints

may be classified as follows:

1. According to position of joints

2. According to position of sleepers

1. According to position of joints: - In this group following two joints may be

classified:

(a) Square joints

(b) Staggered joints

(a) Square joints: - When a joint in one rail is exactly opposite to the joint in

the other parallel rail it is called square joint. It is very common in straight

roads.

(b) Staggered joints: - When a joint in one rail is not exactly opposite to the

joint in the other parallel rail it is called staggered joint. It is used in the

curve section.

2. According to position of sleepers: - In this group following three joints may

be classified:

(a) Suspended joint

(b) Supported joint

(c) Bridge joint

(a) Suspended joint: - When the rails are placed at the centre of two

consecutive sleepers the joint is known as suspended joint. In this

joint load is equally distributed on two sleepers therefore it is widely

used.

(b) Supported joint: - When the sleeper is placed exactly below the rail

joint the joint is called supported joint. The running of this type of

joint is hard and the joint tends to be high. There is heavy wear and

tear of the sleeper supporting the joint and maintenance of the joint

is very difficult.

(c) Bridge joint: - This joint is similar to the suspended joint with the

difference that a length of metal is used to connect the ends of two rails

so that bending stresses may not develop in the rails.

Alignment:-Making the position of centre line on the ground and giving

direction to the railway track is known as alignment of the railway track.

The alignment or location of the railway track comprises of the following two

components:

(a) Horizontal components

(b) Vertical components

(a) Horizontal components: - It includes the straight path its width, curves and

deviations in width and curves.

(b) Vertical components: - It includes changes in vertical curves and gradients.

Importance of the alignment: - Both these components play a vital role in

determine the alignment of a railway track. The alignment of a new railway track

should be done after careful study of the area. The improper alignment would

either prove uneconomical in initial cost of construction or in the maintenance of

the track aligned and construction it becomes impossible to change it due to

increase in cost of adjoining land and high cost of the construction etc.

Factors controlling the alignment: - The various factors which control the

alignment of a railway track are as follows:

1. Obligatory points

2. Traffic

3. Geometric design

4. Topography of the area

5. Economics

6. Other considerations

1. Obligatory points: - These are the points which control the alignment of

the railway track and can be further classified into two groups:

(i) Points through which track must pass like tunnel, a mountain pass, a

bridge or an intermediate town.

(ii) Points through which track not pass should like religious places as

mosques, temples, expensive structure, a fertile land or an area under

consistent water logging or flooding.

2. Traffic: - The alignment should suit traffic growth and its impact should be

studied carefully and as much as possible the alignment should pass

through thickly populated area so as to benefit maximum amount of

people.

3. Geometric design: - To get the maximum benefit of a railway alignment

geometric design standards should be strictly followed. Design features

such as gradients, curves, radius of curves, site distances and the thickness

of foundation and ballast layer should be properly constructed.

4. Topography of the area: - It is general outlook of any area therefore it

should be properly studied carefully in order to study a new alignment. In

topography various features are considered like type and nature of soil,

slope of the ground, any type of water channel like river, pound or stream,

mountain etc.

5. Economics: - Beside other factors the alignment to be finalized should be

economical. The factors like initial cost, cost of the maintenance and cost of

vehicle operation must be taken into account.

6. Other considerations: - Following points should also be consider beside

above mention factors:

(i) Drainage considerations

(ii) Water logging

(iii) Right angles

Requirements of a good alignment: -

It should be feasible and easy to construct and maintain.

It should be economical

It should be safe for traffic

It should be free from any type of the deviation

Yards: - A yard is a system of various number of tracks laid with definite limit for

various purposes such as sorting out vehicles, making up trains, loading,

unloading of cargo and passengers etc.

Types of yards: - Railway yards can be classified into the following categories:

(a) Passenger yards

(b) Goods yards

(c) Marshalling yards

(d) Locomotive yards

Siding: - When a branch line from a main line terminates at a dead end with a

buffer stop is called a siding. The basic function of a siding is to provide temporary

storage for wagons, locomotives etc.

Jetties and groins: - Jetties and groins are structures designed to modify or

control sand movement. A jetty is generally employed at inlets for the purpose of

navigation improvements. When sand being transported along the shoreline by

waves and currents arrives at inlets. Groins are barrier type structures extending

from the backshore seaward across the beach. The basic purpose of a groin is to

interrupt the sand movement along a shore.

Construction: - A jetty is usually constructed of steel, concrete or rock. The type

depends on foundation conditions and wave, climate and economic

considerations. A groin can be constructed in many ways using timber, steel,

concrete or rock but can be classified into basic physical categories as high or low.

Long or short and permeable.

Wharves and breakwaters: - Wharves, breakwaters are marine structures used

for various recreational and commercial purposes. Wharves (docks and piers) are

structures located on the shore and can be used for swimming, fishing or for

securing boats. Breakwater protects the shore line from wave action and coastal

erosion.

Ballast: -

Track ballast forms the track bed upon which railway sleepers or railroad

ties are laid. It is packed between, below and around the ties.

The ballast section is important for the track. It means incase of no of

ballast section the sleepers will implant in the foundation.

Ballast holds the sleepers in position and provides a uniform level surface.

They also provide drainage to the track and transfer the train load to a

larger area of formation.

Purpose of ballast section:

Transfer the load of train to the roadbed.

Stability of sleepers at its position.

Allowing of water to drain.

To provide easy operation and maintenance.

Prevent growing of herbs.

Absorption of impacts.

Design of ballast section: -

Thickness of ballast section must be adequate under the sleepers to

distribute the pressure on the foundation.

The bearing capacity on the foundation is less than the allowable pressure

at least.

Regular pressure distribution.

Placing of ballast

(f) fitting and fastening:

The fitting and fastening are the devices used to connect and provide a grip

between rails and sleepers in order to keep the track in a stable position.

The fitting and fastening are used to keep the rail and sleepers in a compact form.

Rails and sleepers without any joint become loose and cause heavy wear and tear

of the track materials. It should be kept in the mind that joints need about 30%

extra maintenance than the plan track. They provide a grip between rails and

sleepers. The rails are fastened with the sleepers by fittings and fastenings.

Types of fittings and fastenings:

1. Fish plates

2. Bolts

3. Chairs

4. Keys

5. Bearing plates

6. Spikes and screws

1. Fish plates: The function of fish plate is to hold two rails together both

in horizontal as well as vertical planes, at each joint the pair of fish

plates is used; holes are drilled in the fish plate for inserting the bolts.

The rails are fixed together by tighten fish bolts with help of nuts.

Requirements of fish plates:

1. They must be capable to hold the under side of rail and top of foot.

2. There shape should be such that free movement of trains is not disturbed

at any joint.

3. They should be able to absorb shocks develops by jumping wheels over the

expansion gapes of the rail.

4. They should be capable to holds the ends of rail both laterally and

vertically.

5. They should be capable to with stand weir due to impact, expansion or

compaction.

Composition: Carbon, Manganese, Silicon, Sulphur and Phosphorus

2. Bolts:

Types of bolts: a) Fang bolts b) Hook bolts

A) Fang bolts: - This is an alternative to round spikes, fang bolts have proved

more effective, but their fixing and removal is difficult. They are used in

location where gauge is to be preserved.

B) Hook bolts: Hook bolts are used to fix sleepers to girders of bridges. Foe

each sleepers usually have two hook bolts are quite adequate.

3. Chairs: Chairs are used to hold the double headed and bull headed rails

in position. They help in distributing the load from rails to sleepers. The

chairs are fixed with sleepers by means of spikes. Chairs are an

important part of fixing and fastening as they hold the rail tightly in its

position.

Requirements: - chairs are made of cast iron. The shape of chairs depends upon

the type of rail used. The weight of each chair is approximately 20.4 kg.

4. Keys: - They keep the rail in proper position. Wooden keys are cheaper,

but liable to be attacked by vermin’s, therefore a number of metal keys

have been devised, and nowadays Stewart metal key is popular. Another

key were patented by Morgan hence known as Morgan keys.

Requirements: - They were wedge shape wooden or metal pieces.

5. Bearing plates: - Bearing plates are used for fixing or distributing the

load of vehicles from rail to sleeper.

Advantages of bearing plates: -

1. They increase the bearing area on the sleeper and thus decrease loading

intensity.

2. They prevent the rail cutting because the rail cuts the sleepers surface due

to abrasion.

3. They increase the overall stability of the track.

4. They decrease the wear and tear of the spikes.

5. Bearing plates help to maintain the gauge of the track better.

6. The rail cutting on curves is reduced by the use of bearing plates.

6. Spikes and screws: -

The device used to hold the rails with the sleepers are known as the spike. They

can be used with or without chairs and bearing plates.

The rail spike is a large nail with an offset head that is used to secure rails and

base plates to rail load ties in the track.

A rail spike is roughly chisel shaped and with a flat edge point.

Function: - The main function is to keep the rail in gauge.

Requirements of good spikes: -

1. It should be cheep.

2. It should be such that it could be fixed or removed easily.

3. It should be able to hold the rail in proper position and should have enough

resistance again moving loads.

4. It should be able to resist corrosion for a longer period of time.

Requirements of an ideal fastening: -

1. It should be cheap and durable.

2. It should be easy to fix and adjust.

3. It should be capable to absorb shocks and vibration.

4. It should be capable to give sufficient insulation to the electric track.

5. It should be capable to resist creep.

6. It should contain less number of components.

7. It should be able to resist corrosion.

Ports, docks and harbours:-

Port: - A port is a harbour having terminal facilities like landing and picking

passengers and cargo etc. In general it can be said that a port includes a harbour

along with other facilities. In other words we can say that every port is harbour

but inverse is not true.

Docks: - Docks are necessary for discharging of cargo as ships require number of

days for discharging cargo during which period they need a uniform water level. If

ship is subjected to vertical moment by tides great inconvenience will be felt in

lifting the cargo from the ship and special arrangement will be needed for lifting

cargo. Docks are the enclosed required for berthing ships to keep them to float in

uniform level.

Harbour: - A harbour is a sheltered area of the sea where facilities for loading,

unloading of cargo and passengers are provided. A harbor is a body of water

where ships, boats and barges can seek shelter from stormy weather or else are

stored for future use. Harbor can be natural or artificial. An artificial harbor has

deliberately constructed breakwaters, sea walls, jetties or otherwise they could

have been constructed by dredging and these require maintenance by further

periodic dredging.

Classification of harbour: - The harbours are classified as under:

1. Classification depending upon the protection needed

2. Classification depending upon the utility

3. Classification based upon the location

1. Classification depending upon the protection needed: Depending upon the

protection needed, harbours are broadly classified as:

(a) Natural harbour

(b) Semi-harbour

(a) Natural harbour: - Natural formations affording safe discharge facilities for

ships on sea coasts, in the form of creeks and basins are called natural

harbours. The factor such as local geographical features, growth of

population, development of the area etc have made the natural harbour

big and attractive. In other words natural harbour is an inlet protected from

storm and waves by natural configuration of land.

(b) Semi-natural harbour: - This type of harbor is protected on sides by

headlands and it requires man made protection only at the entrance.

Classification depending upon the utility: - Depending upon their utility, harbours

are classified into five major types:

(a) Harbour of refuge

(b) Commercial Harbours

(c) Fishery Harbours

(d) Military Harbours

(e) Marina Harbours

(a) Harbour of refuge: - On dangerous coast-lines, disabled or damaged ships,

under stress of weather conditions will need quick shelters and immediate

repairs.

Requirement of harbour of refugee:

Ready accessible from high seas

Safe and convenient anchorage against sea

Facilities for obtaining supplies and repairs

All type of naval craft, small and big, will need refugee in an emergency and hence

such refugee harbour should provide commodious accommodation. Modern big

ships will require a lot of elbow room for purpose of manoeuving or turning

about.

(b) Commercial harbour: - commercial harbor could be situated on coasts,

estuaries, big rivers on inland river coasts. They do not normally have any

emergency demand like a harbour of refugee and practically the size and

number of ships using such harbours are known factors.

Basic requirement of commercial harbour are: -

Special accommodation for the mercantile marine.

Storage sheds for cargo

Good and quick repairs facilities to avoid delay

More sheltered condition as loading and unloading could be done with

advantage in calmer waters

(c) Fishery harbour: - Harbour should be constantly open for departure and

arrival of fishing ships. Preliminary requirement are loading and unloading

facilities for the perishable fish catch like railway sidings, roads and

refrigerated stores with ample storing space for preserving the catch.

(d) Military harbour: - These harbours are the naval vessels bases which are

meant to accommodate the naval vessels. They serve as supply depot also.

(e) Marina harbour: - This is harbour providing facilities of fuel, washing

machine, telephone etc for small boat owners having temporary or

permanent berths. In other words marina as a small harbour or boat basin

providing dockage, supply and services small pleasure crafts.

Classification based upon the location: - The harbor entrance should be designed

and located for quick easy negotiation by ships overtaken by storms. It should be

narrow enough not to expose. The layout of a harbour is greatly influenced by its

location and based on the location. Harbours are further classified into following

four major types:

(a) Canal harbour

(b) Lake harbour

(c) River harbour

(d) Sea or ocean harbor

(a) Canal harbour: - The harbour located along the canals for sea navigation

and inland is known as canal harbour. It is found that maintenance

dredging of canal basin is generally negligible.

(b) Lake harbour: - The harbour constructed along the shore of lake is known

as lake harbour. If the lake is large then the conditions are similar to those

in ocean expect that ideal action does not occur.

(c) River harbour: - The harbour constructed along the bank of river is known

as river harbour. River creates the main transportation route to join the

hinterland and the sea.

(d) Sea or ocean harbour:- The harbour located on the coast of a sea or an

ocean is called the sea harbour. They are intended for sea going vessels.

Requirements of an ideal harbour: -

For harbour of refugee:

Facilities of obtaining repairs and refugee

Safe and convenient anchorage against the sea

Ready accessibility from the high seas

For commercial harbour:-

Storage shads for cargo

To avoid delay, good and quick repair facilities

Ample space for loading and unloading cargo, and facilities for

transporting loading and unloading cargo

For fishing harbour:-

it should be constantly open for arrival and departure of fishing ships

loading and unloading facilities along with quick dispatch for the

perishable fish catch such as railway sidings and roads should be

there

refrigerated stores with sufficient storing for preserving the fish

Site selection of harbour:-

Availability of cheap land and construction material

Natural protection from waves and winds

Transport and communication facilities

Industrial development of the locality

Sea bed, sub soil and foundation conditions

Availability of fresh water and electrical energy

Favorable marine conditions

Traffic potentiality of the harbour