railway engg1.2

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

RAILWAY TRACK CROSS-SECTION


Railway Engineering

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:


Railway Engineering

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.


Railway Engineering

TYPES OF RAILS

In Indian Railways, rails are of following three types:

Double headed

Bull headed

Flat footed


Railway Engineering

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.


Railway Engineering

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


Railway Engineering

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


Railway Engineering

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


Railway Engineering

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


Railway Engineering

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


Railway Engineering

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)


Railway Engineering

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


Railway Engineering

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


Railway Engineering

RAIL JOINTS

1. Supported joints 2. Suspended Joints


Railway Engineering

RAIL JOINTS

3. Bridge rail joints 4. Welded Rail Joints


Railway Engineering

RAIL JOINTS5. Square or even rail joint

6. Staggered joint


Railway Engineering

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.


Railway Engineering

image

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.


Railway Engineering

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


Railway Engineering

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


Railway Engineering

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.


Railway Engineering

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.


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


Railway Engineering

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


Railway Engineering

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


Railway Engineering

Anti creep device

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


Railway Engineering

Types of fastenings1. Fish plates

Provide full expansionand contraction

Bear vertical and lateralstresses withoutdistortion and resistwear

Provide easy renewaland replacement


Railway Engineering

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


Railway Engineering

Types of fastenings

3. Chairs

These are driven for holding DH and BH rails in the required position.


Railway Engineering

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.


Railway Engineering

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.


Railway Engineering

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.


Railway Engineering

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

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


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


Railway Engineering

Methods of welding rails

Chemical or thermit welding

Flash butt welding

Oxy acetylene welding

Electric arc welding


Railway Engineering

railway engg1.2

Documents

railway engineering

flat footed rails

railthese rails

crossingsnamesh killemsetty

flat footednamesh killemsetty

headed railthe head

double headed bull

suitable track