Railway Engg1.2
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Transcript of Railway Engg1.2
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UNIT 1-RAILWAY ENGINEERING
sleepers, various types, spacing and density, ballasts.
Namesh Killemsetty ^ Transportation Engineering II: Railway Engineering^ Sem 5 (2014) ,Civil @ OPJIT
Railway Engineering
TRANSPORTATION ENGINEERING II
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RAILWAY TRACK CROSS-SECTION
Namesh Killemsetty ^ Transportation Engineering II: Railway Engineering^ Sem 5 (2014) ,Civil @ OPJIT
Railway Engineering
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RAILWAY TRACK CROSS-SECTION
Shown below is a diagram (not to scale) of a typical track formation. Dimensions shown are indicative for a typical BG single line track:
Namesh Killemsetty ^ Transportation Engineering II: Railway Engineering^ Sem 5 (2014) ,Civil @ OPJIT
Railway Engineering
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RAILS
Rails are steel sections laid along two parallel lines over sleepers.
They form a suitable track for the train and should be strong enough to bear the stress developed by the track due to wheel loads, lateral and other forces as well as variations due to temperature changes.
Namesh Killemsetty ^ Transportation Engineering II: Railway Engineering^ Sem 5 (2014) ,Civil @ OPJIT
Railway Engineering
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TYPES OF RAILS
In Indian Railways, rails are of following three types:
Double headed
Bull headed
Flat footed
Namesh Killemsetty ^ Transportation Engineering II: Railway Engineering^ Sem 5 (2014) ,Civil @ OPJIT
Railway Engineering
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TYPES OF RAILS
Double headed rail
The head and foot of the rail were of the same section. The purpose of having head and foot of the same section was to use the foot as head when the head got torn out.
Such rails were supported on chairs which rested on sleepers.
Namesh Killemsetty ^ Transportation Engineering II: Railway Engineering^ Sem 5 (2014) ,Civil @ OPJIT
Railway Engineering
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TYPES OF RAILS Bull headed rail
These rails consist of head, web and foot and are made of steel. The head is larger than the foot and the foot is designed only to properly hold the wooden keys with which the rails are secured to chairs.
They are Easier to manufacture Long life Maintain better alignment Can be removed and replaced easily
Disadvantages: Reduced strength Costly fittings Costly maintenance
Namesh Killemsetty ^ Transportation Engineering II: Railway Engineering^ Sem 5 (2014) ,Civil @ OPJIT
Railway Engineering
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TYPES OF RAILS Flat footed railIn this type of rail, the foot is spread out to form a base. Also known as vignoles rail as invented by Charles Vignoles in 1836.Advantages:
Are strong enough and do no require any chair
Less fittings and hence economical maintenance
Disadvantages Fastenings get loose Difficult to maintain points and
crossings
Namesh Killemsetty ^ Transportation Engineering II: Railway Engineering^ Sem 5 (2014) ,Civil @ OPJIT
Railway Engineering
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Difference between bull headed rail and flat footed railS.No. BULL HEADED RAIL FLAT FOOTED RAIL
1 Weaker for the same cross section
Stronger for the same cross section
2 Fastening to wooden sleepers costlier
Fastening to wooden sleepers less costly
3 Fittings are difficult Fittings are simpler
4 Maintenance of points andcrossings is difficult
Maintenance of points and crossings is simpler
5 Daily inspection of rails is required
Daily inspection not necessary
6 High initial cost Lower initial cost
7 More maintenance cost Less maintenance cost
8 Better suited where lateral loads are more important
More suitable for both lateral and vertical loads
Namesh Killemsetty ^ Transportation Engineering II: Railway Engineering^ Sem 5 (2014) ,Civil @ OPJIT
Railway Engineering
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STANDARD RAIL SECTIONS FOR B.GS.No SPECIFICATION 90R 52kg/m 60kg/m
1 Weight (kg/m) 44.69 52 60
2 Traffic density Upto 10 GMT 20-30 GMT 35 GMT
3 Speed Upto 100 kmph
Upto 130 Kmph
Upto 160kmph
4 Service life 20-25 years 20-25 years 20-25 years
Advantages for heavy sections: Suitable for diesel and electrical engines Lower sleeper density Stronger Smaller deflection under load
Weight of rail section in kg/m = 1/510 X weight of locomotive in tonnes
Namesh Killemsetty ^ Transportation Engineering II: Railway Engineering^ Sem 5 (2014) ,Civil @ OPJIT
Railway Engineering
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LENGTH OF RAILS
Maximum possible length is advisable as it would reduce the number of joints.
Less number of joints would result in stronger track, less number of fittings and fixtures and economical maintenance.
The factors which decide the length of rails are:
Ease of transportation
Reasonable cost of manufacture
Ease in loading into the available wagons
Namesh Killemsetty ^ Transportation Engineering II: Railway Engineering^ Sem 5 (2014) ,Civil @ OPJIT
Railway Engineering
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LENGTH OF RAILS
Indian Railways have adopted the following length of rails:
For Broad Gauge tracks : 13m (42)
For Middle Gauge and Narrow Gauge tracks: 12m (39)
Namesh Killemsetty ^ Transportation Engineering II: Railway Engineering^ Sem 5 (2014) ,Civil @ OPJIT
Railway Engineering
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RAIL JOINTS
Rail joints should satisfy the following requirements:
Ends to remain true
Should be strong and stiff
Provide for expansion
Perfectly elastic (laterally and vertically)
Ends should not get battered
Provide facility for removal and replacement
Economical in cost
Namesh Killemsetty ^ Transportation Engineering II: Railway Engineering^ Sem 5 (2014) ,Civil @ OPJIT
Railway Engineering
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RAIL JOINTS
Various types of rail joints:
1. Supported joints
2. Suspended joints
3. Bridge rail joints
4. Welded rail joints
5. Square or even rail joint
6. Staggered joint
Namesh Killemsetty ^ Transportation Engineering II: Railway Engineering^ Sem 5 (2014) ,Civil @ OPJIT
Railway Engineering
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RAIL JOINTS
1. Supported joints 2. Suspended Joints
Namesh Killemsetty ^ Transportation Engineering II: Railway Engineering^ Sem 5 (2014) ,Civil @ OPJIT
Railway Engineering
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RAIL JOINTS
3. Bridge rail joints 4. Welded Rail Joints
Namesh Killemsetty ^ Transportation Engineering II: Railway Engineering^ Sem 5 (2014) ,Civil @ OPJIT
Railway Engineering
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RAIL JOINTS5. Square or even rail joint
6. Staggered joint
Namesh Killemsetty ^ Transportation Engineering II: Railway Engineering^ Sem 5 (2014) ,Civil @ OPJIT
Railway Engineering
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Coning of wheels
The art of providing an outward slope of 1:20 to the treads of wheel is known as coning of wheels.
Advantages of coning of wheels
Uniform wear of the head of rail
Maintenance of proper gauge
Increased life of sleeper
Disadvantages of coning of wheels
Horizontal thrust may sometimes increase gauge distance
Sleepers under outer edges of the rail are likely to be damaged.
Namesh Killemsetty ^ Transportation Engineering II: Railway Engineering^ Sem 5 (2014) ,Civil @ OPJIT
Railway Engineering
image
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Tilting of railsPlacing the rails of the track at an inward slope of 1 in 20 is known as tilting of the rails.
The main purpose of this treatment is to reduce the wear on the inside edges of the rail in a track.
Namesh Killemsetty ^ Transportation Engineering II: Railway Engineering^ Sem 5 (2014) ,Civil @ OPJIT
Railway Engineering
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Wear of rails
Wear of rails may take place as follows:
At top of rails due to direct impact of the load from the wheel due to
abrasion,
grounding and corrosion resulting in grinding of sand particles getting deposited at head of the rails
Flowing of metal due to heavy concentrated loads.
Corrosion of exposed area on being subjected to humid conditions or burning of metal during starting on account of slipping of wheels and on stopping during braking action
Namesh Killemsetty ^ Transportation Engineering II: Railway Engineering^ Sem 5 (2014) ,Civil @ OPJIT
Railway Engineering
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Wear of rails
At the end of the rails due to Impact of the blow
Greater pressure on sleeper and ballast causing depression on the end
Settlement of the ballast
Sleeper getting worn out due to pressure at the joint
Wear on the side of the head of the rail taking place along the curved track when the vehicle does no bend to the shape of the curvature
Namesh Killemsetty ^ Transportation Engineering II: Railway Engineering^ Sem 5 (2014) ,Civil @ OPJIT
Railway Engineering
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Creep of railsCreep in rails denoteslongitudinal movement ofrails in the track. Principalcauses of creep are:
Percussion theory
Impact of wheels at the endof facing rail at each fishplate joint results in thedepression of the trailing railwhich results creep in theforward direction.
Namesh Killemsetty ^ Transportation Engineering II: Railway Engineering^ Sem 5 (2014) ,Civil @ OPJIT
Railway Engineering
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Creep of rails Wave theory
The train wheels cause depression under themselves forming lifts or crests immediately at the rear and in the front. This action pushes the rail forward resulting creep in the forward direction.
Namesh Killemsetty ^ Transportation Engineering II: Railway Engineering^ Sem 5 (2014) ,Civil @ OPJIT
Railway Engineering
-
Causes of creep in rails
Due to uneven expansion, due to expansion and contraction of rails
The braking action tends to push the rail forward resulting creep in the forward direction.
Creep is greater in the curved portion than in the straight portion
Creep is more on a track with a steep gradient
In a single line track, creep results in the direction of traffic
Namesh Killemsetty ^ Transportation Engineering II: Railway Engineering^ Sem 5 (2014) ,Civil @ OPJIT
Railway Engineering
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Effects of creep
Difficulty in refixing of rail
Operation of switches becomes difficult
Points and crossings get pulled or pushed
Rail joints get opened
Surface of the track gets disturbed
Alignment of the track gets disturbed
Ballast is forced out of the plate
Namesh Killemsetty ^ Transportation Engineering II: Railway Engineering^ Sem 5 (2014) ,Civil @ OPJIT
Railway Engineering
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Prevention of creep
Introduction of anti creep devices
By pulling back the rails
By increasing number of sleepers per rail
By improved drainage
By using steel sleepers
By using good quality ballast
Namesh Killemsetty ^ Transportation Engineering II: Railway Engineering^ Sem 5 (2014) ,Civil @ OPJIT
Railway Engineering
Anti creep device
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Rail fastenings
Fastenings are required to keep the rails in their position by connecting the rails and
to allow for expansion and contraction,
maintain required tilt of the rails
Maintain points and crossings, and
Correct the track alignment vertically and laterally
Namesh Killemsetty ^ Transportation Engineering II: Railway Engineering^ Sem 5 (2014) ,Civil @ OPJIT
Railway Engineering
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Types of fastenings1. Fish plates
Provide full expansionand contraction
Bear vertical and lateralstresses withoutdistortion and resistwear
Provide easy renewaland replacement
Namesh Killemsetty ^ Transportation Engineering II: Railway Engineering^ Sem 5 (2014) ,Civil @ OPJIT
Railway Engineering
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Types of fastenings2. Bearing plates
Flat footed rails do not provide adequate bearing area on the timber sleeper and hence bearing plates are used to distribute the load over larger area.
Not required for B.H and F.F rail
Namesh Killemsetty ^ Transportation Engineering II: Railway Engineering^ Sem 5 (2014) ,Civil @ OPJIT
Railway Engineering
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Types of fastenings
3. Chairs
These are driven for holding DH and BH rails in the required position.
Namesh Killemsetty ^ Transportation Engineering II: Railway Engineering^ Sem 5 (2014) ,Civil @ OPJIT
Railway Engineering
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Types of fastenings
4. Spikes
4.1. Dog Spike: These are named due to the shape of their heads. Used for holding flat footed rails to wooden sleepers.
Namesh Killemsetty ^ Transportation Engineering II: Railway Engineering^ Sem 5 (2014) ,Civil @ OPJIT
Railway Engineering
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Types of fastenings
4. Spikes
4.2. Screw Spike: They are tapered screws with V ends. For BG tracks, 165 mm long spike is used.
Namesh Killemsetty ^ Transportation Engineering II: Railway Engineering^ Sem 5 (2014) ,Civil @ OPJIT
Railway Engineering
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Types of fastenings
5. Bolts: Fish plates are connected to rails with the help of Fish bolts. Four to six fish bolts are used with each pair of fish plate.
Namesh Killemsetty ^ Transportation Engineering II: Railway Engineering^ Sem 5 (2014) ,Civil @ OPJIT
Railway Engineering
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Types of fastenings
6. Keys : Keys are used for making different rail connections. They can be classified as metal keys and wooden keys.
Some common types of metal keys include stuartskey and morgan keys
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Welding of rails
The theory of keeping gaps in joints proportional to the length of the rails followed previously no longer holds good.
In a conventional jointing of rails a 13 m rail, 8mm of expansion joint is provided
Namesh Killemsetty ^ Transportation Engineering II: Railway Engineering^ Sem 5 (2014) ,Civil @ OPJIT
Railway Engineering
-
Advantages of welded rail
Saving of upto 25% in the cost of maintenance
Knocking effects at the joints is eliminated
Considerable reduction in creep
Due to reduced wear at the ends, the life of the rail is increased
Decrease in construction and maintenance cost due to the reduction in the number of joints.
Welding increases length of the rail by welding two joints
Saving of fuel by reduction of tractive effort
Namesh Killemsetty ^ Transportation Engineering II: Railway Engineering^ Sem 5 (2014) ,Civil @ OPJIT
Railway Engineering
-
Methods of welding rails
Chemical or thermit welding
Flash butt welding
Oxy acetylene welding
Electric arc welding
Namesh Killemsetty ^ Transportation Engineering II: Railway Engineering^ Sem 5 (2014) ,Civil @ OPJIT
Railway Engineering