Solved Question papers Transportation Engineering II

1. Explain the role of rail Transportation in the development of country (8 Marks) Since its creation Indian Railways has successfully played the role of the prime carrier of goods and passengers in the Indian Subcontinent. As the principal constituent of the nation’s transport infrastructure, the railway has important role to play.

1. Railways provide the cheapest and most convenient mode of passenger transport both for long distance and suburban traffic.

2. Railways have played a significant role in development and growth of industries. Growth of textile industry in Mumbai, jute industry in areas surrounding Kolkata, coal industry in Jharkhand, etc is largely due to the development of railway network in these areas. Railways help in supplying raw materials and other facilities to the factory sites and finished goods to the market.

3. Agriculture also owes its growth to railways to a great extent. Now farmers can sell their agricultural produce to distant places and even sell them in the world market at remunerative prices.

4. Railways are also helpful in removing isolation between cities and countryside and have played a significant role in disseminating innovations and new ideas.

5. Railways are particularly suited to long distance journey and provide a strong medium of national integration.

6. Railways play a vital role in mitigating the sufferings of the people in the event of natural calamities like droughts, floods, famines, earthquakes, etc. This is done by carrying relief and rescue teams and essential items to the affected areas and save people from sufferings and starvation.

7. Railways also help in facing man-made calamities like social, political, religious disturbances, insurgency, etc. It facilitates easy movement of police, troops, defence equipment, etc. The importance of railways to save the country’s freedom and integrity from external aggression has been proved at several occasions.

8. Railways carry the British legacy and connect major ports, thereby lending a helping hand to the overall prosperity of the coastal areas.

9. Introduction of superfast trains and container services in major cities of India have ensured quick movement of men and material.

10. Railways are especially suited to long haulage of bulky materials like coal, petroleum and ores.

2. What are the different types of rails used in Indian railways? Mention their advantages.

There are mainly three types of rails used1. Double headed2. Bull headed

3. Flat footed

The first rails used were double headed (DH) and made of an I or dumb-bell section (Fig. 6.1). The idea was that once the head wore out during service, the rail could be inverted and reused. Experience, however, showed that while in service the bottom table of the rail was dented to such an extent because of long and continuous contact with the chairs that it was not possible to reuse it. This led to the development of the bull headed (BH) rail, which had an almost similar shape but with more metal in the head to better withstand wear and tear (Fig. 6.2). This rail section had the major drawback that chairs were required for fixing it to the sleepers.

A flat-footed rail, (Fig. 6.3), with an inverted T-type cross section of inverted T- type was, therefore, developed, which could be fixed directly to the sleepers with the help of spikes. Another advantage of the flat-footed rail is that it is a more economical design, giving greater strength and lateral stability to the track as compared to a BH rail for a given cross-sectional area. The flatfooted (FF) Rail has been standardized for adoption on Indian Railways.Double HeadedThey mainly have 3 components

1. Uppertable2. Wed3. Lower table

Both Upper and lower tables are identical in shape and they were introduced with the hope of doubling the life of the rails. i.e when the upper table is wornout then the rail can be inverted and reused by fixing the upside down. But the idea soon turned out to be wrong as due to continuous contact of the rail with the chair made the surface of the lower table rough and hence the smooth running of the train was impossible

Bull headedIt is similar in shape to double head rail. The only difference between double headed and bull headed rail is that in bullheaded rail more metal is added to the head to allow the greater wear and tear. The lower head or table was kept of just sufficient size to be able to withstand the stresses to be induced by moving loads. This rail also required chair for fixing it to the sleeper. This proved the greatest drawback of this rail

The advantages and disadvantages are given in the other question

3. Mention the requirements of Ideal Permanent way.

Permanent track is regarded to be semi elastic in nature. There is possibility of track getting disturbed by the moving wheel loads. The track should, therefore, be constructed and maintained keeping the requirements of the permanent way.

1. The gauge should be correct and uniform2. The rails should be in proper level, in a straight track, two rails must be at the same level. On

curves, the outer rail should have proper superelevation and there should be proper transition at the junction of the straight and a curve

3. The alignment should be correct. i.e it should be free from kinks or irregularities.4. The gradient should be uniform and as gentle as possible. Any change of gradient should be

followed by a smooth vertical curve, to give smooth riding quality

5. The track should be resilient and elastic in order to absorb shocks and vibrations of running track.

6. The track should have enough lateral strength, so that alignment is maintained even due to effects of

a. Side thrust on tangent lengths and centrifugal force on curvesb. Lateral forces due to expansion of rails, particularly in case of welded rails

7. The radii and superelevation on curves should be properly designed and maintained8. Drainage system must be perfect for enhancing safety and durability of track9. Joints, including points and crossings which are regarded to be weakest points of railway

track, should be properly designed and maintained10. If there is trouble from the creep, the preventionary measures should be to prevent it11. The various components of track, i.e the rails, fittings, sleepers, ballast and formation must

fully satisfy the requirements for which they have been provided12. There should be adequate provision for easy renewals and replacements.13. The track structure should be strong, low in initial cost as well as maintenance cost.

4. Draw neatly the cross section of a straight Broad Gauge Railway Track in Cutting for Double Lane and Single Lane in Embankment

5. Define creep. What are the possible causes and effect of creep?

Creep of railsCreep is defined as the longitudinal movement of rails with respect to the sleepers in a trackIndications of creep

1. Closing of successive expansion spaces at rail joints in the direction of creep and opening out of joints at the point from where the creep starts

2. Marks on flanges and webs of rails made by spike heads, by scraping or scratching as the rail slide

The main factors responsible for the development of creep are as follows.

Ironing effect of the wheel The ironing effect of moving wheels on the waves formed in the rail tends to cause the rail to move in the direction of traffic, resulting in creep.Starting and stopping operations When a train starts or accelerates, the backward thrust of its wheels tends to push the rail backwards. Similarly, when the train slows down or comes to a halt, the effect of the applied brakes tends to push the rail forward. This in turn causes creep in one direction or the other.Changes in temperature Creep can also develop due to variations in temperature resulting in the expansion and contraction of the rail. Creep occurs frequently during hot weather conditions.Unbalanced traffic In a double-line section, trains move only in one direction, i.e., each track is unidirectional. Creep, therefore, develops in the direction of traffic. In a single-line section, even though traffic moves in both directions, the volume of the traffic in each direction is normally variable. Creep, therefore, develops in the direction of predominant traffic.Poor maintenance of track Some minor factors, mostly relating to the poor maintenance of the track, also contribute to the development of creep. These are as follows.(a) Improper securing of rails to sleepers(b) Limited quantities of ballast resulting in inadequate ballast resistance to the movement of sleepers(c) Improper expansion gaps(d) Badly maintained rail joints(e) Rail seat wear in metal sleeper track(f) Rails too light for the traffic carried on them(g) Yielding formations that result in uneven cross levels(h) Other miscellaneous factors such as lack of drainage, and loose packing, uneven spacing of sleepers.

Effects of CreepThe following are the common effects of creep.Sleepers out of square The sleepers move out of their position as a result of creep and become out of square. This in turn affects the gauge and alignment of the track, which finally results in unpleasant rides.Disturbance in gaps. Due to creep, the expansion gaps widen at some places and close at others. This results in the joints getting jammed. Undue stresses are created in the fish plates and bolts, which affects the smooth working of the switch expansion joints in the case of long welded rails.Distortion of points and crossings Due to excessive creep, it becomes difficult to maintain the correct gauge and alignment of the rails at points and crossings.

Difficulty in changing rails If, due to operational reasons, it is required that the rail be changed, the same becomes difficult as the new rail is found to be either too short or too long because of creep.Effect on interlocking The interlocking mechanism of the points and crossings gets disturbed by creep.Possible buckling of track If the creep is excessive and there is negligence in the maintenance of the track, the possibility of buckling of the track cannot be ruled out.Other effects There are other miscellaneous effects of creep such as breaking of bolts and kinks in the alignment, which occur in various situations.

6. Mention the advantage of having uniform gauge in the country

Gauge to be used in a particular country should be uniform throughout as far as possible, because it will avoid many difficulties experienced in a non uniform system. The uniformity of gauges results in the following advantages.

1. The delay, cost and hardship in transhipping passangers and goods from the vehicles of one gauge to another is avoided.

2. As the transhipping is not required there is no breakage of goods.3. Difficulties in loading and unloading are avoided and labour expenses are saved.4. Possibility of thefts and misplacement, while changing from one vehicle to another, is

eliminated5. Large sheds to store goods are not required6. Labour strikes etc. do not affect the service and operation of trains 7. Surplus wagons of one gauge cannot be used on another gauge. This problem with not arise if

gauge is uniform8. Locomotives can be effectively used on all the tracks of a uniform type of gauge is adopted.9. Duplication of equipment such as platforms, sanitary arrangements, clocks etc,. is avoided.

This saves a lot of extra expenditure10. During military movement, no time is wasted in changing personnel and equipment from one

vehicle to another if gauge is uniform11. It is quite expensive to convert one gauge into another at a later stage as it may require new

rolling stock, fresh construction and widening of bridges and tunnels.12. Due to late arrival of trains at the junction, where change of gauge is involved, the missing

links results in number of difficulties.

7. Draw a neat sketch of double line B.G track Cross section in curves. Mention various component parts.

8. What are the different types of welding of rails? Explain any two of them

Types of welded rails

Short Welded Rails (SWR). A short welded rail is one which con tracts and expands throughout its entire length due to temperature variations. These rails are welded into 3, 5 or 10 rail lengths to make Short Welded Rails. The Short Welded Rails of 3 rail length ha v e be e n s t a nd e r d i z e d on I nd i a n r a i l w a y s .

Long Welded Rai ls (LWR). Long Welded Rail is one whose-central part does not undergo any longitudinal movement and only end portions are affected due to temperature variations. The minimum length of more than 200 m in ease of B .G. and 300 m for M.G. will function as Long Welded Rail. The maximum length of LWR is prescribed as one kilometre (1000 m) under Indian conditions.

Continuous Welded Rails (CWR). The Welded Rails longer than one kilometre and extending from one station to other with switch expansion joint are called C.W.R.

9. Compare between bull headed, double headed and flat footed rails

Points of comparision

Flat-footed rail Bull-headed rails na double headed rails

Strength and stiffness they have more strength and stiffness for same weight

They have less strength and stiffness for same weight

Laying and relaying Fitting of these rails is simpler and so can be easily laid and re-laid

The fitting of these rail is difficult and time consuming as they are supported on chairs

Arrangement at points, crossings and at sharp curves

The arrangements are simpler and easy

The arrangements are complicated and difficult

Alignment and stability of track

In this impact of rolling wheels affect the fittings

These rails when fitted on chairs, provide a more solid, smooth track

Initial Cost Lesser cost More cost is required because of costly fastening

Rigidity More rigid They are less rigidInspection Daily inspection is not necessary Daily inspection of wooden

keys is necessaryMaintenance cost Is less MoreSuitability More suitable because of better

stability, economy, strength and stiffness

More suitable at places where lateral loads are more important rather than vertical loads

F.F railsMerits

1. They have more strength and stiffness, both vertically and laterally, than B.H rails2. Fitting of rails with sleepers is simpler, so they can be easily laid and relaid3. No chairs or keys are required as in case of B.H. Rails4. In points and crossings, the arrangements are simpler than B.H. rails

Demerits1. The fitting get loosened more frequently than in case of B.H rails2. The straightening of rails, replacing of rails and dehogginf of battered rails are difficult

B.H railsMerits

1. They keep better alignment and give more solid and smoother connection with the latter2. The heavy chairs with larger bearing on sleepers give longer life to wodden sleepers and

greater stabilityDemerits

They require additional cost of iron chairs They have less strength and stiffness They require heavy maintenance cost

Double .HeadedAs in double headed rails does not have any advantages as the main concept of using a double head in the rail failed due to the damages caused on the lower end or the rails due to fasteningDemerits

They require additional cost of iron chairs They have less strength and stiffness They require heavy maintenance cost

10. What is coning of wheel? What are the advantages of coning of wheels

The head of the wheels of railway vehicle are not flat but made sloped, and this sloping of surface along the circumference forms a part of a cone. On straight tracks, the coning of the wheels keep them centrally, thereby reducing the wear of wheel flanges. If at any movement the wheels go out of the central portion, then they have to travel unequal distance due to the change in diameter of inner and outer wheel thus forcing it back to the central position and hence the ride will be smoother.

The problem, however, arises in the case of a curve, when the outer wheel has to negotiate more distance on the curve as compared to the inner wheel. Due to the action of centrifugal force on a curve, the vehicle tends to move out. Hence the conning of wheel helps in outer wheel to travel larger distance since it has larger diameter of the wheel and the inner wheel will travel smaller distance because it has smaller diameter of wheel. The wheels of a railway vehicle are connected by an axle, which in turn is fixed on a rigid frame. Due to the rigidity of the frame, the rear axle has a tendency to move inward, which does not permit the leading axle to take full advantage of the coning. The rigidity of the frame, however, helps to bring the vehicle back into central alignment and thus works as a balancing factor. On rails laid flat, conning of the wheels will subject the rails to eccentric loading at the inner edge. This would create problem in both rail design and maintenance. To avoid this rails are not laid flat but they are instead tilted inwards at a slope of 1:20. Which is the slope of wheel cone. This is called as canting of rails.

Coning of wheels causes wear and tear due to the slipping action. It is, however, useful as(a) It helps the vehicle to negotiate a curve smoothly,(b) It provides a smooth ride, and(c) It reduces the wear and tear of the wheel flanges.

11. Sketch the rail sections with dimensions. Discuss the criteria for deciding the cross section and length of rails.

a) 52 kg rail b) 60 kg rail

The length of rail depends upon the maximum length- size that manufacturers can produce at a reasonable cost. Longer rails lengths require expensive arrangements at the rail mills for their controlled cooling, stacking and handeling. Another limiting factor is the problem of transport. Theoretically, the longer the rail, the lesser the number of joints and fittings required and the lesser the cost of construction and maintenance. Longer rails are economical and provide smooth and comfortable rides. However, the length of rail is governed by the following considerations

1. The length of rail which can be manufactured at the reasonable cost2. The rails should be of such length that they may be carried in the largest wagon

available3. The length of rail is also limited by the facilities available for lifting or handling the

rail4. The length of shortest rail should be larger than largest rigid wheel base of wagon

The length of a rail is, however, restricted due to the following factors.

(a) Lack of facilities for transport of longer rails, particularly on curves.(b) Difficulties in manufacturing very long rails.(c) Difficulties in acquiring bigger expansion joints for long rails.(d) Heavy internal thermal stresses in long rails.Taking the above factors into consideration, Indian Railways has standardized a rail length of 13 m (previously 42 ft) for broad gauge and 12 m (previously 39 ft) for MG and NG tracks.

But, Rail weld or rail joint is the know zone of weakness in track structure hence should avoided to the extent that is possible. The rolling of rails in longer length is therefore encouraged. The new rail rolling set up by zindal steel and power lmd in india, is rolling rails upto length of 120 m each.

Weight of rail

Though the weights of a rail and its section depend upon various considerations, the heaviest axle load that the rail has to carry plays the most important role. The following is the thumb rule for defining the maximum axle load with relation to the rail section:

Maximum axle load = 560 × sectional weight of rail in lbs per yard or kg per metre

12. What is meant by wear of rails? How do you classify the wear? Discuss the various causes of wear?

Type of Wear on RailsClassification based on location

1. On sharp curves2. On gradient3. On approaches to stations, where brakes are frequently applied4. In tunnels

a. Where sand is used on rails to produce more friction on damp rails but on the contrary it gives more wear

b. In tunnels, the gases emitting from the engine being confined attack the metal and results in wear.

5. In coastal area, due to action of sea breeze, the corrosion of metal takes place6. On weak foundation- sinking of rails due to heavy loads gives uneven surface which results

in wearOn bases of portion of wear

1. Wear on top of head of rail2. Wear at the ends of rails3. Wear on the sides of head

Wear on top of rails

1. Due to flow of metal- this is because the heavy loads concentrated on small area produce the stresses which exceed the elastic limit and hence plastic flow of metal takes palce and burrs are formed, which later get chipped off by moving wheel flanges

2. and its recurring impact causes the wear at the top pf rails3. Due to abrasion of rolling wheels, the rails generally get worn out at the top of rails4. Due to constant brakes application, which results in skidding and burning of the rail head.

This finally results in excessive wear and abression5. Due to use of sand which is spread to produce friction in case of dampness in tunnels. The grinding

action of sand particles with rails gives rise to wear.6. Due to fluctuations in gradients.7. Due to corrosion of rails by the action of sea breeze, which also gives rise to wear on top of rails.8. Due to weak tracks viz., loose packing of ballast or loose fitting of rails and sleepers increase,

war.On curves. The wear on top of rails at curves is die to the following causes

1. Due to slipping or skidding of wheels2. Due to effect of centrifugal force and improper superelevation, load on one rail is greater than

the other. If superelevation is more or less for a given speed, the load will be more on inner or outer rail respectively

3. Due to adzing of sleepers: on curves the sleepers have to be laid at a slope for the purpose of superelevation, but when the rail is laid at a slope of 1 in 20 on sloping sleeper, the resulting slope or tilts s different from the slope of wheel cone, giving lesser a of contact between the wheel and the rail, resulting in more wear due to heavy concentration of stresses

Wear at ends of rails

This type of wear is encouraged due to following factors:1. Due to loose fish plates and fish bolts2. Due to heavy loads and larger joint openings3. Difference in rail levels at joints4. Small wheels5. Bad condition of the vehicle springs6. Poor maintenance of the track

Wear on sides of the rail head: This type of wear is only prominent when the rails are laid at curves. This type of wear is more than first two types of wear and is most distructive in nature. This wear occurs due to following causes

1. At curves, there is greater thrust on inner rail, when trains run at lesser speed than equilibrium speed2. due to rigidity of the wheel base3. slipping and skidding of wheels at curves.

13. Draw a neat sketch showing the details of double line B.G. track with electrical traction

14. Draw a typical Cross section of a permanent way. Discuss in brief the basic functions of various components of railway track.

Fig : Typical Cross section of a permanent way on embankment

The combination of rails, fitted on sleepers and resting on ballast and subgrade is called the railway track or permanent way. Sometimes temporary tracks are also laid for conveyance of earth and materials during construction works. In a permanent way, the rails are joined in series by fish plates and bolts and then theya are fixed to sleepers by different types of fastening. The sleepers properly spaced, resting on ballast, are suitably packed and boxed with ballast. The layer of ballast rests on the prepared sub grade called the formation.

The component of permanent way include1. Rails2. Sleepers

3. Fasteners4. Ballast 5. Subgrade

The rails act as girders to transmit the wheel load to the sleepers and also it provides level surface for train movement.

The sleepers hold the rails in proper position with respect to the proper position with respect to the proper tilt, gauge and level, and transmit the load from rails to the ballast.

In a permanent way, the rails are joined in series by fish plates and bolts and then they are fixed to sleepers by different types of fastening.

The ballast distributes the load over the formation and holds the sleepers in position.

Subgrade transfers and distributes load to soil layer

On curved tracks, super elevation is maintained by ballast and the formation is levelled. Minimum ballast cushion is maintained at the inner rail, while the outer rail gets more ballast cushion. Additional quantity of ballast is provided on the outer edge of the track for which the base width of the ballast is kept more than for a straight track.

15. Mention the Economic, political and social significance Of Railways

Economic Significance

Indian railways is the backbone of the country’s economy. Its role as a service provider and the nation builder is all penetrating. It has unfailingly ensured that fruits of development are distributed far and wide within the country. It facilitates large scale production by increasing mobility of raw materials, workers, consumption of heavy, bulky and perishable commodities by cheap and speedy transportation. Railway have contributed to time- distance convergence. It has introduced competition, and bring stability and uniformity in prices. Since the railway ownership is within the control of union government, it may be better utilised in accordance with developmental needs, public, welfare, national security and defence.

Political significance

1. There is a strong link amoung various parts of the country with a good network of rails. Today, India is held together by the railways, which roll day and night, cutting across racial and regional barriers. It has forged bonds of unity and brings different cultures an people together

2. It contributes for national defence through provision of logistic support3. Development of railways and the colonising activities has gone hand in hand4. Railways help maintenance of internal security, law and administration

Social significance

Railways have greatly influenced social life and brought revolutionary changes in social values, beliefs, contacts and way of living. Before development of railways, social life was local in character. It has promoted social mobility of people. Frequent mixing of people,

break short sighted social values and new social values has emerged based on reason and scientific thinking. Persons of different caste, creed, colour, language and religion come into contact which strengthens brotherhood and social mingling

Unit 2

1. Explain with a neat sketch the important features of cast iron sleepers

CST-9 Sleeper has got following features1. The tie bar is fastened to the plate by means of four standard cotters. Small variation

in gauge can be corrected by these four cotters2. The shape of cost iron support os such as to give a stable base for the rail, and high

lateral and longitudinal stability to the track3. The sleeper may be used in sections of track in corrosive conditions such as saline

soil, industrial waste etc4. The bearing area is approximately equal to the effective bearing area of a wooden

sleeper5. This sleeper forms the rigid track subjected to vibrations under moving loads without

any damage or absorption6. The cantilever ends of the rails are long which lead to battering, and ultimately

hogging of the rail end and deterioration of ballast under the joint which finally need the replacement of sleeper.

7. This type of sleeper is suitable for speeds upto 110 KMPH8. If used for tracks above speed of 110 kmph, due to the shallow depth of the bowl,

packing becomes loose under vibrations at high speedAs the sleeper does not have a flat bottom, it is not quite suitable for mechanical maintenance with tie tamers.

1. The suitability of a CST-9 sleeper on Long Welded Rails (LWRs), particularly on the breathing lengths, is doubtful because of rigid fastenings and the inability of the fastenings to hold the rail with a constant toe load.

2. The rail seat wears out quickly causing the keys to come loose.

3. The sleeper has only limited longitudinal and lateral strength to hold LWRs particularly in the breathing length.

4. Due to the use of less metal under rail seat, the shocks and vibrations are directly transmitted to the ballast, resulting in poor retention of packing (loose packing) and hence an increased frequency of attention.

2. With neat sketches explain the various types of spikes and also mention the requirements of good spike

The requirements of a good spike are1. First of all, the spike should be strong enough to hold the rail in position and it should

have enough resistance against motion to retain its original position so that it does not lead to creep

2. The spike should be as deep as possible, for better holding power3. The spike should be easy in fixing and removal from the sleepers4. The spike should be cheap in cost5. It should be capable of maintaining the gauge

Dog spikes

For holding the F.F. Rails to a wooden sleeper, dog spikes are commonly used. These are simply stout nails to hold rail flanges with timber sleepers. The shape of head of spike resembles with ear of the dog and hence its nomenclature as dog spike. The section of the spike is square-shape and bottom part is either pointed,blunt or chisel shaped. They are cheapest, easy in fixing and removing from sleepers and maintain a better gauge than scre spikes.

Screw spikes

These are tapered screws with V threads used to fasten the rails with timber sleepers. The head is circular with square projection

Screw spike has double the holding power as that of dog spike an can also resist lateral thrust in a better way as compared to dog spikes. However, the screw spikes are costly and with that their use, the gauge maintenance become difficult

Round spikes

Round spikes with a head either cylindrical or hemispherical are used for fixing chairs of B.H. Rails to wooden sleepers for fixing slide chairs of points and crossings. These have a blunt end and limited use

Standard spikes

These are used for cast iron chairs only to fix them with timber sleepers

Elastic spikes

Actually the main disadvantage with the dog head spikes is that due to wave motion the spike comes out hence the fastening will get loose. To over come this disadvantage elastic spikes are introduced which will absorb the wave motion without getting loose

Dog Spikes• It is used to hold flat footed rails to a wooden sleeper.• The shape of the top head resembles that of a dog, hence the name.• The section of the spike is square shaped and the bottom part is either pointed, blunted

or chisel shaped.• They are cheap and easy to install, but they move out of place due to wave motion,

resulting in creep.

SCREW SPIKE• These are tapered screws with V threads used to fasten rails with timber sleepers.• The head is circular with a square projection.• Screw spikes have more than double the holding power of dog spikes but they are

costly and maintenance is more difficult.

3. Briefly explain the advantages and disadvantages of any three types of ballast

Type of ballast Advantages Disadvantages SuitabilitySand ballast Good drainage

properties Cheap „

No noise produced „ on the track

Good packing „

material for CI sleepers

Causes excessive wear

Blows off easily Poor retentively

of packing Track cannot be

maintained to highstandards

Suitable for CI pot sleeper tracks

Not suitable for high-speed tracks

Moorumballast

Cheap, if locally available

Prevents water from percolating

Provides good aesthetics

Very soft and turns into dust

Maintenance of track the difficult

Quality of trackaverage

Used as a sub-ballast

Initial ballast for new

construction

Coal ash or

cinder

Easy availability on railways „ Very cheap „ Good drainage

Harmful for steel sleepers Corrodes rail

bottom and steel sleepers

Soft and easily pulverized

Maintenance is difficult

Normally used in

yards and sidings

Suitable for repairs

of formations floods andemergencies

Not fit for high-speed tracks

Broken stoneballast

Hard and durable when procured from hard rocks

Good drainage properties

Is stable, and resilient to the track

Economical inthe long run

Initial cost is high Difficulties in

procurement Angular shape

mayinjure woodensleepers

Suitable for high speedtracks

4. Draw the dimensional sketch of fish plate. Also state the requirements of Fish plate

Requirements of fish plates1. They must support the underside of the rail and top of the foot2. They should allow a free movement of rails for expansion and contraction for this

purpose, they should not touch web of the rail3. They must be of such a section as to bear the stresses due to lateral and vertical

bending moments without getting distorted and must absorb the shock caused by the jumping of wheel over the gap

4. They should hold the end of rail both laterally in line and vertically in level5. They should be provided against the wear of fish plate due to impact expansion and

contraction

6. Strength should be atleast 58 to 67 kg/cm2

7. Minimum Elongation required is 20%8. Sectional area of fish plate and rail section should be same9. Strength should approximately be of 55% of rail strength

5. Mention the various requirements of ballast. Mention different types of ballast used in permanent way

Ballast material should possess the following properties.1. It should be tough and wear resistant.2. It should be hard so that it does not get crushed under the moving loads.3. It should be generally cubical with sharp edges.4. It should be non-porous and should not absorb waterIt should resist both attrition and

abrasion.5. It should be durable and should not get pulverized or disintegrated under adverse

weather conditions.6. It should allow for good drainage of water.7. It should be cheap and economical.

Different types of ballast used in permanent way are as follows

1. Sand ballast2. Moorum ballast3. Coal ash or cinder4. Broken stone ballast5. Other types of ballast

6. Mention the requirement of ideal sleeper1. Holding the rails in their correct gauge and alignment2. Giving a firm and even support to the rails3. Transferring the load evenly from the rails to a wider area of the ballast4. Acting as an elastic medium between the rails and the ballast to absorb the blows and

vibrations caused by moving loads5. Providing longitudinal and lateral stability to the permanent way6. Providing the means to rectify the track geometry during their service life.7. To support the rails at proper level in straight tracks and at proper super elevation on

curves8. The initial as well as maintenance cost should be minimum.9. The weight of the sleeper should be moderate so that it is convenient to handle.10. The designs of the sleeper and the fastenings should be such that it is possible

to fix and remove the rails easily.11. The sleeper should have sufficient bearing area so that the ballast under it is

not crushed.12. The sleeper should be such that it is possible to maintain and adjust the gauge

properly.13. The material of the sleeper and its design should be such that it does not break

or get damaged during packing.14. The design of the sleeper should be such that it is possible to have track

circuiting.15. The sleeper should be capable of resisting vibrations and shocks caused by the

passage of fast moving trains.

16. The sleeper should have anti-sabotage and anti-theft features.17. Fittings of the sleepers should be such that they can be easily adjusted during

maintenance operations such as easy lifting, packing, removal and replacement.

7. Explain the basis for arriving at minimum depth of ballast section

Minimum depth of Ballast sectionThe load on the sleeper is transferred through the medium of the ballast to the formation. The pressure distribution in the ballast section depends upon the size and shape of the ballast and the degree of consolidation. Though the lines of equal pressure are in the shape of a bulb, yet for simplicity, the dispersion of load can be assumed to be roughly 45° to the vertical. In order to ensure that the load is transferred evenly on the formation, the depth of the ballast should be such that the dispersion lines do not overlap each other. For the even distribution of load on the formation, the depth of the ballast is determined by the following formula Sleeper spacing = width of the sleeper + 2 × depth of ballast If a BG track is laid with wooden sleepers with a sleeper density of N + 6, then the sleeper spacing would be 68.4 cm. If the width of the sleeper is 25.4 cm, then the depth of the ballast cushion would be

A minimum cushion of 15–20 cm of ballast below the sleeper bed is normally prescribed on Indian Railways

8. Explain the following 1) sleeper density 2) concrete sleeper

Sleeper Density and Spacing of SleepersSleeper density is the number of sleepers per rail length. It is specified as M + x or N + x, where M or N is the length of the rail in metres and x is a number that varies according to factors such as (a) axle load and speed, (b) type and section of rails, (c) type and strength of the sleepers, (d) type of ballast and ballast cushion, and (e) nature of formation. If the sleeper density is M + 7 on a broad gauge route and the length of the rail is 13 m, it means that 13 + 7 = 20 sleepers will be used per rail on that route. The number of sleepers in a track can also be specified by indicating the number of sleepers per kilometre of the track. For example, 1540 sleepers/km. This specification becomes more relevant particularly in cases where rails are welded and the length of the rail does not have much bearing on the number of sleepers required. This system of specifying the number of sleepers per kilometre exists in many

foreign countries and is now being adopted by Indian Railways as well. The spacing of sleepers is fixed depending upon the sleeper density. Spacing is not kept uniform throughout the rail length. It is closer near the joints because of the weakness of the joints and impact of moving loads on them. There is, however, a limitation to the close spacing of the sleepers, as enough space is required for working the beaters that are used to pack the joint sleepers.

Concrete SleepersThese types of sleepers were promoted because of shortage of good wooden sleepers and need for better design and economy of sleepers on sustainable basis.These sleepers are mainly of two types

1. Reinforced cement concrete sleepers2. Pre-stressed concrete sleepers

Experiments have shown that concrete sleepers are idela material for sleeper for the following reasons

1. They are made of a strong homogeneous material, impervious to effect of moisture and is unaffected by the chemical attack of atmospheric gases or sub –soil salts

2. It is easily moulded to size and shape required by scientific investigation, to withstand the stresses produced by fast and heavy traffic

Advantages and disadvantagesConcrete sleepers have the following advantages and disadvantages.Advantages

• Durable with life range from 40-50 years• They can be produced on large quantities locally by installing a plant• Heavier than all other types thus giving better lateral stability to the track• Good insulators and thus suitable for use in track circuited lines• Efficient in controlling creep - They are not attacked by corrosion• Free from attacks of vermin and decay, suitable for all types of soils• Most suitable for welded tracks- Prevent buckling more efficiently• Initial cost is high but proves to be economical in long run• Effectively and strongly hold the track to gauge• Inflammable and fire resistant

Disadvantages(a) Handling and laying concrete sleepers is difficult due to their large weights.Mechanical methods, which involve considerable initial expenditure, have to be adopted for handling them.(b) Concrete sleepers are heavily damaged at the time of derailment.(c) Concrete sleepers have no scrap value.(d) Concrete sleepers are not suitable for beater packing.(f) Concrete sleepers should preferably be maintained by heavy ‘on track’ tampers.