Chapter 5 Introduction to railway
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Transportation is regarded as an index of economic progress in a country. The key modes of transport are land, water, and air. Railways are a major form of land transport and have various economic, social, and strategic advantages. Railways have helped integrate people across religions and regions. They allow for efficient administration and rapid mobilization during emergencies. Railways also facilitate mass migration and have broadened social outlooks by enabling travel. Economically, railways increase mobility, transport goods, provide employment, and increase land values near stations. The essential components of a railway track include rails, sleepers, ballast, and other fixtures that work together to form a strong yet flexible surface for train movement.
Chapter 5 Introduction to railway
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- 2. Transportation is regarded as an index of economic, social and commercial progress of the country”. Modes of Transport • Land transport • Water transport • Air transport Two major means of land transport are Roads and railways. INTRODUCTION
- 3. Advantages of Railways • Railway have joined people of different castes, religions customs and traditions. • With adequate network of railway central administration has become easy and effective • Role of railway during emergencies in mobilising troops and war equipment has been very significant. • Railway have helped in mass migration of people.
- 4. Social Advantages • Feeling of isolation has been removed from the inhabitants of Indian villages. • The social outlook of the masses has been broadened through railway journeys. • Railway has made it easier to reach religious importance • Provide safe and convenient mode of transport for the country
- 5. Economic advantages • Mobility of people has increased. • Transport food and clothes during famines. • Transport raw material to the industries • Provide employment to millions of people. • Land values increased due to industrial development. • Price stabilisation is possible.
- 6. COMPONTENTS OF RAILWAY TRACK
- 7. The high carbon rolled steel sections, which are laid end-to-end. They are fixed to the sleepers by various fastening and rest on sleepers. To provide continuous and leveled surface for the trains to move For carrying axle loads of the rolling stock Materials of rails: Cast – iron Malleable iron Wrought iron steel Types of rails: •Double Headed Rail •Flat Footed Rails •Bull Headed Rails RAILS
- 8. SLEEPER The members laid transverse under the rails for supporting and fixing them the gauge distance known as “sleeper” Functions: Supports the rails firmly Maintains the uniform gauge on track Distributes the weight coming on the rails over a sufficiently large area of ballast Acts as an elastic medium between rails and ballast to absorb vibrations of trains Maintain alignment of the track Sleepers also add stability of the permanent way
- 9. BALLAST Layer of broken stones,gravel,moorum or any other granular material (20-60 mm size) packed below and around sleepers is known as ballast. Provided with side slope - 1.5 :1
- 10. Functions: To provide a hard and smooth surface for the ballast to rest on Hold the sleepers in place during the passage of trains To transmit and distribute the load from sleepers to formation Allow for maintaining correct track levels without disturbing the rail road bed. Protect the surface of formation from direct exposure to sun, frost or rain. To form an elastic bed To drain the water immediately and keep the sleepers in dry condition To discourage the growth of vegetation
- 11. SUB BALLAST A layer of moorum, gravel or small aggregate is provided between the ballast and the earth embankment to drain off the water immediately, its call sub ballast. EMBANKMENT It is also known as the formation, it is provided by levelling the ground & necessary cutting & filling. The embankment is provided side slope of 1:2.
- 15. Railway Gauge The clear horizontal distance between the inner (running) faces of the two rails forming a track is known as Gauge. (see in fig given below) This gauge of 1435 mm has been universally used in Great Britain, France, Germany, U.S.A., Canada and most other countries of Europe and is thus known as the world standard gauge. In India broad gauge used which has standard size 1676 mm.
- 16. RAIL GAUGES The different gauges can broadly be divided into the following four categories: 1) Broad Gauge: width 1676 mm to 1524 mm 2) Standard Gauge: width 1435 mm and 1451 mm 3) Metre Gauge: width 1067 mm, 1000 mm and 915 mm 4) Narrow Gauge: width 762 mm and 610 mm 7
- 17. RAIL GAUGES Following are the factors affecting the choice of a gauge: 1. Traffic Condition: If the intensity of traffic on the track is likely to be more, a gauge wider than the standard gauge is suitable. 2. Development of Poor Areas: The narrow gauges are laid in certain parts of the world to develop a poor area and thus link the poor area with the outside developed world. 1 7
- 18. RAIL GAUGES 4. Speed of Movement: The speed of a train is a function of the diameter of wheel which in turn is limited by the gauge. The wheel diameter is usually about 0.75 times the gauge width and thus, the speed of a train is almost proportional to the gauge. If higher speeds are to be attained, the B.G track is preferred to the M.G or N.G track. 1 8
- 19. RAIL GAUGES 3. Cost of Track: The cost of railway track is directly proportional to the width of its gauge. If the fund available is not sufficient to construct a standard gauge, a metre gauge or a narrow gauge is preferred rather than to have no railways at all. 1 9
- 20. RAIL GAUGES 5. Nature of Country: In mountainous country, it is advisable to have a narrow gauge of the track since it is more flexible and can be laid to a smaller radius on the curves. This is the main reason why some important railways, covering thousands of kilometers, are laid with a gauge as narrow as 610 mm. 2 0
- 21. Uniformity of Gauges Gauge to be used in a particular country should be uniform throughout as far as possible, because it will avoid many difficulties.
- 22. Advantage of uniformity of Gauges Delay cost and hardship in transferring passengers is avoided Transshipping is not require, so no breakage of goods Avoided difficulties in loading and unloading Possibilities of thefts and misplacement is eliminated Labour strikes do not affect the services and operation of train Large sheds are not require for storage Surplus wagons of one gauge can not be used on another gauge Duplication of equipment such as platforms, sanitary arrangements, etc is avoided During military movement, no time is wasting of changing equipment
- 23. REQUIREMENTS OF AN IDEAL PERMANENT WAY The following are the principal requirements of an ideal permanent way or of a good railway track :- i. The gauge of the permanent way should be correct and uniform. ii. The rail should be in proper level in straight portion. Proper amount of super elevation should be provided to the outer rail above the inner rail on curved portion of the track. iii. The permanent way should be sufficiently strong against lateral forces. iv. The curves, provided in the track, should be properly designed. v. An even and uniform gradient should be provided through out the length of the track. vi. The tractive resistance of the track should be minimum. vii. The design of the permanent way should be such that the load of the train is uniformly distributed on both the rails so as to prevent unequal settlement of the track.
- 24. viii. All the components parts such as rails, sleepers, ballast, fixtures and fastenings, etc. should satisfy the design requirements. ix. All the points and crossings, laid in the permanent way, should be properly designed and carefully constructed. x. It should be provided with proper drainage facilities so as to drain off the rain water quickly away from the track. xi. It should be provided with safe and strong bridges coming in the alignment of the track. xii. It should be so constructed that repairs and renewals of any of its portion can be carried out without any difficulty.
- 25. Rails The rails on the track can be considered as steel girders for the purpose carrying axle loads. Flat footed rails are mostly used in Indian railways. Functions of Rails • Provide hard, smooth and unchanging surface for the passage of heavy moving loads with minimum friction steel rails and steel wheels. • The rail material should be such that it gives minimum wear to avoid replacement and failure. • Rail transmit loads to the sleepers and consequently reduce pressure on ballast and formation below.
- 26. TYPES OF RAIL SECTIONS • Double headed rails(D.H Rails) • Bull headed rails(B.H rails) • Flat footed rails(F.F rails)
- 28. Weight & length of rails: Indian railways have standardized flat footed rails for their use on BG, MG, NG. the types of rail is defined by the weight of rail per meter length. 55 R means the weight of rail is 55 kg/m. The length of rails used in India are: BG – 12.80 m, MG – 11.89 m (for BG length is increase 19.2 to 25.6 m) Sr. No. Gauge Types of rail Weight in Kg/m 1 B.G. 55 R 55 45 R 45 35 R 35 2 M.G. 35 R 35 30 R 30 25 R 25 3 N.G. 25 R 25
- 29. SLEEPERS these are members laid transverse to the rails on which rails are supported and fixed to transfer the loads from rail to ballast and subgrade below. Functions of sleepers: ▪ To hold the rails to correct gauge. ▪ To act an elastic medium between the ballast and rail to absorb the blows and vibrations due to moving loads. ▪ To distribute load from the rail to the index area of ballast or to the girders in case of bridges. ▪ To support rails - at proper level in straight tracks - at proper super elevation on curves
- 30. Requirements of sleepers • Sleeper should be economical i.e, minimum initial and maintenance cost. • Fitting of the sleepers should be easily adjustable during maintenance operations. Such as ✓ Lifting ✓ Packing, ✓ Removal and replacements. ✓ The weight of the sleeper should not be too heavy or excessively light i.e. with moderate weight they should be for ease of handling. ✓ Design of sleepers should be such a way that the gauge and alignment of track and levels of the rails can easily adjusted and maintained. ✓ The bearing area of sleepers below the rail seat and over the ballast should be enough to resist the crushing due to rail seat and crushing of ballast under sleepers. ✓ Design and spacing such a way to facilitate easy removal and replacement of ballast.
- 31. • Sleepers should be capable of resisting shocks and vibrations due to passage of heavy loads of high speed trains. • Sleepers design should be such a way they are not damaged during packing process. • Design should be strong enough so that they are not pushed out easily due to the moving trains especially in case of steel sleepers with rounded ends. • An ideal sleeper should be anti-sabotage and anti-theft qualities.
- 32. Types of sleepers sleepers Wooden sleepers Iron sleepers C.I. sleepers Steel sleepers Concreter sleepers RCC sleepers Pre-stressed concrete sleepers
- 33. Sleeper density sleeper density is the number of sleepers per rail length It is specified as (n + x) where, n = length of rail in meter x = variable factor = 1, 2, 3,…..etc. For instance, If length of rail is 12.8 m, 17 sleepers are expressed as (n + 4) i.e. (13 m+ 4) This (n+ 4) is the density of sleepers. In India, sleeper density varies from (n + 4) to (n + 6). In Britain, sleeper density is (n + 4), In USA, sleeper density varies from (n + 9) to in (n + 11).
- 34. Factors governing sleeper density 1. Axle load and speed 2. Type and section of the rail 3. Type of ballast 4. Type of sleeper, i.e. bearing area of sleeper
- 35. 2. BALLAST Ballast is a layer of broken stone, gravel, or any other suitable material placed under and around the sleepers for distributing the load from the sleepers to the formation
- 37. Functions of Ballast It provides a suitable foundation for the sleepers. It transfer and distributes loads from the sleepers to a larger area of formation. it provides effective drainage to the track. It helps in protecting the top surface of the formation.
- 38. Physical Properties of Good Ballast It should be hard and tough. It should wear resistant and durable. It should be non-porous and non-absorbent of water. It should be cheaper and easily available. It should not be brittle. It should not allow rain water to accumulate
- 39. Types of ballast Following materials can be used as ballast: 1. Broken stone It is the best material to be used as ballast. Generally on all important tracks broken stone ballast has been used. Blast of Igneous rocks is the most suitable 2. Gravel It stands second in suitability as ballast. Used in large quantities in many countries. It is obtained from river beds
- 40. 3. Cinders The residue obtained from the coal used in locomotives is known as Cinder. 4. Sand It stands fourth in merits as ballast material. Coarse sand is better than fine sand. 5. Brick ballast Where stone or other suitable ballast is not available, over burnt brick ballast can be used. 6. Kankar It is found in the form of particles of varying sizes. Where stone is not easily and at reasonable price available, kankar can be used as road metal and ballast for railway tracks.
- 41. Volume of ballast For 1 meter length the quantity of ballast required as below B.G. – 1.036 mᶟ M.G. – 0.071 mᶟ N.G. – 0.053 mᶟ
- 43. Joints To hold together the adjoining ends of rails in the correct position to ensure continuity. It is weakest part of the track. It is only 50% of the strength of a rail Gap is 6 to 15 mm kept between to end of rails Sleeper are provided at closer at the end of rail joints Joints are eliminated up to 1 km of length of track for meeting higher speed.
- 44. Types of Joints Types according to position of joints Square joints Staggered joints Types according to position of sleepers Suspended joints Supported joints Bridge joints
- 45. Types of Joints Square joints When a joint in one rail is exactly opposite to the joint in the parallel rail it is called as square joint. Very common type of joint in straight track. Staggered joints When a joint in one rail is exactly opposite to the centre of the parallel rail length it is called as staggered joint.
- 47. Types of Joints Suspended rail joint: When rail ends are projected beyond sleepers it is termed as suspended joint. This type of joint is generally used with timber and steel through sleepers. Supported rail joints: When the rail ends rest on a single sleeper it is termed as supported joint. The duplex joint sleeper with other sleepers is an example of the supported joint.
- 48. Types of Joints Bridge joints: When the rail ends are projected beyond sleepers as in the case of suspended joint and they are connected by a flatter corrugated plate called as bridge plate it is termed as a bridge joint.
- 50. CONING OF WHEELS The distance between the inside edge of wheel flanges is kept less than the gauge.
- 51. CONING OF WHEELS The Surface of wheels are made in cone shape at an inclination of 1 in 20, and the same slope is provided in the rails (see fig), this is known as coning of wheels. The diameter of wheel is different at different cross section of the wheel, when the train running on the straight track try to move in any direction. Flat wheels of train would cause shock loads to the sides of the rails because of lateral movement between wheels and the rails. The coning of wheels is mainly done to maintain the vehicle in the central position with respect to the track.
- 52. CONING OF WHEELS whereas on a curved track, due to centrifugal force the train is forced in outward direction, the diameter on outer track increases and the distance on two tracks are adjusted. Purpose: To keep the train in its central position of the rails, coning does not allow any sidewise movement on a straight track. to allow the wheels to move different distances on a curved track and thereby reduce wear and tear.
- 53. Advantages of coning the wheels Coning the wheels reduces the depreciation of the wheel rims and rails. Depreciation is caused because of the friction action of rims with inner faces of the rail top. Coning also gives an option of lateral drift of the hinge with is wheels. Coning also prevents, to some extent, the slipping of the wheels.
- 54. ADZING OF SLEEPER To provide a cant (slope) of 1 in 20 in the rails, the wooden sleepers have to be cut to this slope at rail seat. This process of cutting the wooden sleeper at 1 in 20 is known as adzing of sleeper. For concrete or steel sleeper, the top surface of sleeper is provided with slope of 1 in 20.