UNIT I – RAILWAY PLANNING

PERMANENT WAY A System of rails fitted on sleepers which rest on ballast and everything supported by a sub- grade is known as permanent way It is a rail road on which train run. It primarily consist of 2 rails running parallel at specified distance depending upon gauge of track.

COMPONENTS OF RAILWAY TRACK

The railway track has the following component, – Rails – Sleeper – Ballast – Formation

1. RAILS Rails are members of the track laid in two parallel lines to provide on our continuous and land surface for the movement of Trains. They are unsymmetrical I Section made up of steel which is fitted by fishplate or welding Function of rails (a)Provide a continuous and level surface (b) Provide a pathway which is smooth and less friction (c) Lateral guide for the wheels (d) Bear changes due to vertical loads etc. (e) Transfers to formation through sleepers on wider area.

LENGTH OF RAILS Longer rails are economic & give greater strength. Therefore longer rails are preferred than shorter rails Indian railways adopt a std rail length 13m for BG (Std Gauge) & 12m for MG Joint are the weakest point in railways track Therefore welding of joints are done by pressure or melting together. It may be SWR- Short welded rails LWR- Long welded rails CWR- Continuous welded rails

Length of Rails On Indian Railways the standard lengths are the following: Length = m. (42 ft.) for BG (say 13 m) and Length = m. (39 ft.) for MG (say 12 m)

TYPES OF RAILS

RAIL GAUGE The gauge of a railway track is defined as the clear minimum perpendicular distance between the inner faces of the two rails.

Dimension of gauges 1. Broad Gauge(BG) 1676mm(5’6”) 2. Standard Gauge(SG) 1435mm 3. Meter Gauge(MG) 1000mm 4. Narrow Gauge(NG) 762mm(2’6”) 5. Light Gauge 610mm

CREEP OF RAILS Creep is defined as the longitudinal movement of the rail with respect to the sleepers.

Defects of Creep (i) Sleepers move out of position thereby the rail gauge. (ii) Position of points and crossings are disturbed. (iii) Interlocking mechanism gets disturbed.

Remedies or Prevention of Creep Pulling back of rails Provision of Anchors or Anticreepers. Use of steel sleepers. Anticreeper

Kinks In Rails When the ends of adjoining rails move slightly out of position, “shoulders” or “kinks” are formed. Measures taken to rectify kinks in rails: 1.By correcting alignment at joints and at curved locations. 2.Proper packing of joints. 3.Proper maintenance of the track periodically in repect of cross levels, gauge, alignment, welding of worn out portions etc.

Buckling of Rails Buckling means the track has gone out of its original position or alignment due to prevention of expansion of rails in hot weather on account of temperature variations.

CONING OF WHEELS It is art of providing a inward slope of 1 in 20 to the wheel treads of rolling stock. To prevent lateral movement the treads of wheel are given a slope 1 in 20 which is known as coning of wheel If tread of wheels are kept flat there will be lateral movement of wheel axle & wheels will damage the inside edge of rails

Coning of Wheel on Level-track

CONING OF WHEELS

CANTING OF RAILS In order to minimize eccentric loading at inner edge to coning, rails are tilted inwards. This is called canting of rails

Rail Fixtures & Fastening A rail fastening system is a means of fixing rails to rail road ties The term rail anchors, tie mates, chairs & track fasteners are used Requirement of Ideal fastening 1) It should be easy to fix & to adjust 2) it should be cheap 3) it should be non-corrosive 4) it should be capable of absorbing shocks and vibrations

Track Fittings & Fastenings Fish plates Spikes – Dog spikes – Screw spikes – Round spikes – Standard spikes – Elastic spikes Bolts – Dog or Hook bolt – Fish bolt – Rag bolt – Fang nut and bolt Keys – Wooden key for C.I. Chair – M.S. key and steel trough sleepers – Stuart’s key – Morgan key – Cotter and tie bars Chairs – Cast steel chairs – Mild steel and Cast Iron Slide Chairs

Blocks – Heel blocks – Distance blocks – Crossing blocks – Check blocks Plates – Bearing Plates – Saddle Plates Track Fittings & Fastenings contd..

Fish Plate

Dog Spike

Screw spikes

Chair

Bearing Plate

TRACK STRESS Stresses in the railway truck are produced due to many causes listed below, – The wheel load – The hammer blow – Stresses due to irregularities in the track – Additional stresses on curves – The pressures by the flanges of heel on sides of rails

Defects in Rails/Damaged Rails These are the rails which should be removed on account of their becoming unsafe for a railway track.

Rail Features Crushed Heads Split Heads / Split Web Flowing Metal in Heads Horizontal Fissures & Transverse Fissures Horizontal Cracks Square or Angular Break Head & web separation Foot & web separation Bolt hole crack Rail corrosion

Crushed Head

Split Heads

Horizontal and Transverse Fissures

Flowing Metal in Heads

Rail joints & Fastenings Two rails are connected by a joint which forms the weakest part of the track Different fastening are used based on the following, – Depending on position of joints Square joint Staggered joints – Depending on position of sleepers Suspended joint Supported joint Bridge joint

Depnding on position of sleepers

Rail Joint

Insulated Joint

ii) SLEEPER

III) BALLAST

IV)SUB-GRADE Or FORMATION Sub grade Is naturally occurring soil prepared to support components of railways track- ballast, sleepers & rail Sometimes natural ground may not meet the requirement as per bearing capacity. In such case raised bank is constructed over natural ground which is called embankment Sometimes formation may be below the natural ground in that case is called cutting

REQUIREMENT OF SUB-GRADE / FORMATION Uniform transmission of load over a larger area Effective drainage of water entering from top Support ballast & rails from beneath & provides a graded surface from them to rest PATTERN OF FAILURE OF EMBANKMENT: i) Toe failure ii) Base failure iii) Slope failure

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