Abstract

Self Stabilising Track

Abstract

India is having the second largest network of railway in the world. It is the most likely transportation medium compare to other, therefore important of railway is increasing day by day, because of which the responsibility of this sector is more compare to other. The responsibility comprises of convenience, comfort and safety, therefore the proper attention should be given to these aspects.

The traditional technique and method of construction are not enough to avoid the problem like severe accident due to derailment, rail-failure, vibration and shocks from rail-wheel coaches-passengers.

One new technique brought forward by konkan railway corporation to minimize the above mention problem to some extent, that new technique is call self-stabilizing track (s. s. t.).Introduction

In the technique of SST the basic focus is given on the foundation where in the ballast which was to be use below sleeper traditionally is pre-compacted and firmly comfort wire mesh cage of specific shape arrange in a particular manner, combined with each other to provide vertical support to the sleeper as well as improve later resistance to the track where it is possible to make the response of track under running train to stabilize the track rather than be de-stabilizing the track which was resulting to severe accidents.

History of railway

In accident times Romans were first to try in the running of animal-drawn vehicles over two parallel lines of stone and bricks embedded in the ground. In the 15th century wooden planks and beams were used in place of stone in Europe and England and such type of roads were known as tramways. Good speeds were obtain on such tramways by horse-drawn vehicles. But such wooden rails had short life because they wore out quickly and caused many difficulties. To increase the life of wooden rails, these were covered with iron plates and such covered plates were known as pathways. After some time a new idea, for preventing the lateral movement of wheels by using angle irons in place of plane iron sheets development of the modern railways. Later on these angel irons replaced by cast iron rails with raised flanges on outer side, because those raised flanged were more useful in preventing the lateral movement of vehicles.

When it was observed that the animals can draw the vehicles on C.I.rails at good speed than on roads, the people of the 17th century started thinking about some mechanical device which could replace the animals. It is understood that in France Nicholas Cugnot was first to get success in 1771, in the construction of a steam locomotive. In Britain in 111786 William Murdock, a Scotsman, also get success in the preparation of steam locomotive model. In 1797 a Cirnish Engineer Trevithick also did a lot of work on steam locomotive and got success in 1804 in the design and construction of a steam locomotive. In this way history tells us that a number of engineers tried to build a locomotive in the early days, but actually George Stephenson (1781-1848) was the first man to get complete success in this field.

George Stephenson completely designed, planned, construction and got success in the running the first train of the world on 27th September 1825 in England between Stockton and Darlington in the country of Durham.

After this the development of railway was started rapidly in all the parts of the world.

Development of railways in India

Before the introduction of railways the communication means in India were extremely poor in ninetieth century. Actually it was only Lord Dalhousie, who insisted for the development of railway in India. Mr. M. Stephenson to east India Company put up the first proposal for the construction off railways in 1844. East India Company undertook the construction of experiment line from Calcutta to Mirzapur in 1849. Similarly another contract to construct a railway line from Bombay to Kalyan was given was given in 1850 to India Peninsula railway.

The first train in India was run at 3.30 p. m. on 16th April 1853 between Bombay and thane. It carried about 400 people in 14 coaches and was driven by three engines.

Component of permanent way

1) BALLAST: -The ballast is the crushed stone made up of hard kind of granite, quartz, basalt, sand, stone and lime with an ultimate crushing strength of at least 700Kg/cm2. the stone and lime stone with an ultimate crushing strength of the railway and therefore upon the traffic intensity, the quality of ballast as well ass upon the soil used for the formation.

According to difficulty of working them, the difficult kind of ballast are classified as soft(sand), medium(gravel and shell) and heavy(crushed stone and ballast France slag).

Following material are used as ballast

Quartz sand with grains ranging from 0.1to 3mm, graded gravel with fraction from 3to 60in size, hard kind of crushed stone from 25to 70 mm in size, acidic metallurgical slag with a fine crystalloid, compact structure in formation from 25ro 70 mm (normal) or 7to 25mm(fine),as well as whole or broken sea shells with fraction from 0.5mm or made in size amounting to least 50% of the total weight.

Function of ballast

1) to uniformly distribute the load from sleepers over a large area of formation.

2) To hold the sleeper in position by acting as their foundation and preventing their lateral and longitudinal movement.

3) To provide elasticity and resilience it the track.

4) To provide an easy method for traffic adjustment such ass alignment and gradient without any disturbance to formation.

5) To prevent the growth of weed inside the track.

2)SLEEPER: -following different types off sleepers are uses in railway construction

a) wooden sleepers.

b) Steel sleepers.

c) Cast iron sleepers.

d) RCC sleepers.

e) Wooden sleepers: - Prestressed concrete sleeper.

a) Wooden sleepers:-

These sleepers satisfy all the requirement and are only suitable for track circuiting. In India ass the climate changes from place to place, it difficult to choose best wood for sleepering. The life of the wooden sleeper depend on the quality of timber used and its ability to were wood for sleepiring purpose, but due to its heavy cost it is used only in girder grider for sleepering. Sal wood is harder and strong than teak wood as well as cheaper in cost. But now a days, the use of wooden sleeper is avoided.

b)steel sleeper:-

these consist of steel through made out of about 6mm thick steel sheets with its both ends bent down to check thee running out of ballast. The main disadvantage of steel sleeper is that they get rushed very quickly and sometime get cracked or even broken and cause much difficulties.

c)cast iron sleeper: -

these are generally of following types.

i.pot sleepers.

ii.Plate sleepers.

iii.Box sleepers.

iv.C. S. T. 9 sleeper.

v.Duplex sleepers.

The main disadvantage of cast iron sleepers is that they are liable to crack and break but broken pots have a salvage value and be melted further for casting new one.

d) RCC sleepers: -

there are two types of RCC sleepers. First type is like a wooden sleeper, i.e. one-piece sleepers. Second type, two RCC slab are joining together by mean of tie bar generally of a T-section. To avoid disintegration off concrete, sleeper under heavy traffic, metal-bearing plates are provided at the rail seat with a shock-absorbing pad. The concrete sleepers are not affected by natural decay or insects etc. hence they have long life of 40 to 60 years under normal condition. They are not affected by chemical action of the cinder, ballast and soil salt.

Concrete sleepers have some disadvantages

Their heavy weight (2.5to3 times than wooden sleepers) possesses great difficulty in transportation, laying and handling. Pads and plugs are require for fixing the spikes. During packing, the bottom edge are damage. If concrete sleeper is cracked or broken, the scrap value is almost nil.

e) prestressed concrete sleeper:-

these sleepers are costly initially, but are very cheap in the long run.

There are two types of prestressed concrete sleepers.

i. Pre-tensioned concrete sleepers.

ii. Post tensioned sleepers.

Most of the disadvantages of concrete sleepers, but even then these have so many disadvantages. in case of train derailment, these are totally damage and require replacement. Special ballast bed is require for the laying of these sleepers. Due to their heavy cost, these are uneconomical. They require costly maintains. The design and manufacturing of these sleepers is difficult and even then the require strength is not developed in these sleepers. They also require special rail fastening.

Function of sleepers: -

i. Sleeper holds the rail in proper gauge, exact on straight track and loose at curve as per standard.

ii. Sleeper transfers the load of the train from rail to the ballast or girder of the bridge.

iii. Sleeper provides stability to the track.

iv. Sleeper acts ass the elastic medium between the rail and ballast.

v. Sleepers hold the rail in proper level or transverse tilt on curve.

vi. Sleeper also hold the each rail in 1in 20 tilt i.e. the slop of the wheel cone.

3) RAIL: -originally dumb-belt or double headed section were designed in which both thee heads were provided with the same cross section. The main object in designing such a section was that when the one top section his worn out due to moving wheel, it could be inverted and reuse with lower section at the top. But such rail were practically used, it was found that due to the impact of wheel, the lower tread become dented and could not be used for the smooth riding, therefore the rail section was originally designed and only require quantity of steel to keep the stresses within the safe limit was kept in bottom and more metal was used in the bull headed rails and are held in position by mean of chairs fixed to sleepers. These rails are made up of 9.144m to 18.288m in length and 29.77 to 49.62 Kg/m in weight.

At the same time, when bull a headed rail was designed, vignole inverted other type off rail known as flat footed rails section. Vignoles made idea of developing such a rail was that this rail can be used directly on sleeper with small fastening. In India both bull headed and flat footed rails are used which are rolled to B.S. section. When the flat footed rails are directly laid on wooden sleepers, it is found that heavy rail load sunk the rail in the sleeper, therefore to avoid this sinking and for distributing the load on wider area, steel bearing plates are used between sleeper and rail. The main advantage of flat footed rail is its lateral rigidity due to which it is mostly used in Indian Railway.

Functions: -

i. For heavy and concentrated moving load of train, rail provides hard, smooth and even surface with lowest fraction between rail and steel wheel.

ii. Rail transfer the load of the train form the wheel to the sleeper, ballast and the formation within the safe limit.

iii. Rails have to bear the thermal stress due to change in temperature as well as breaking force caused while stooping the train.

iv. Rails have to bear the vertical and lateral forces of the train moving at high speed.

v. Rail are made of such high carbon steel which has minimum were even in worst possible condition of atmosphere and fraction between the rail and the wheel.

Objects: -Following are the main objects of railway

1) to connect together existing line or opening up a new communication for treat between two centers for through traffic.

2) To serve political or military purpose e.g. the Khyber Pass Railway of world was two.

3) To shorten or improve the existing through rout e.g. Miraj-Panddaarpur railway.

4) To relive connect of traffic by opening up an alternative route between two terminal e.g. between San-Francisco and New-York, there are number of railways routs.

5) To spread feeder lines to open up undeveloped track, of the network of railway in Saurashtra.

6) To relive over crowing of passengers traffic in suburban areas of capital cities for which in addition to one or more surface railway, underground railway and some times elevated railway are provided.

Self stabilizing track

The railway use rails fitted on sleepers with double elastic fastening and concrete sleepers, ballast providing necessary self-draining load distributing, as well ass geometry correction medium. The ballast under the action of moving trains get subjected to disturbing vibrations and geometry is disturbed as ballast loses its compactness and yields.

The new construction propose is based on a new concept propose in New theory for rail-wheel interaction. By suitable control of the inertia of mass of ballast that vibrates in track, it is possible to make the response of track under running trains to stabilize rather than be de-stabilizing the track.

In the propose track, predetermined quantities of ballast are precompacted and firmly confirmed, so that the gross mass that vibrates is enhanced to cause inertia damping of many orders higher than, compared to free unrestrained ballast. Further an elastic medium in the form a reinforced rubber or polyethylene layer of the order of a few milli-meters thick, inserted between the sleeper bottom and the top of the confined ballast block, modified the coefficient of restitution and also helps in controlling the vibration profile below the sleeper.

The over all effect is to reduce frequency and amplitude of vibrations being transmitted below the sleeper because of moving train-with ballast not getting disturbed, and formation protected from destabilizing vibrations. The confined ballast in performed wire mesh cages of specific shapes arranged in a particular manner, combine with each other to provide elastic vertical support to the sleeper ass well ass improved lateral resistance to the track.

There are three types of performed cages, which hold ballast:1) shaped with a rectangular long caged ballast element or T shaped ones.

2) Flat squarish caged ballast element for support under sleeper and distribute load on formation.

3) Additional vibriable thickness element comprising off a bottom plate of metal or fiber reinforced material below the sandwiched elastic element which allows insertion of fine quarry chips of measured amount to correct track geometry within 5 to 110mm.

The ballast duty packed firmly in the cage and subjected to preloading of defined value will be the building element in the shaped shown, to support the sleeper and rail in track, replacing the conventionally used loose ballast, which is compacted in situ by tie-tamping machines working on tracks.

By using these modular ballast filled cages, we also achieve saving of material in ballast used for conventional track, which could of the order of 70%, because in the middle one-third of sleeper no ballast will be needed, in additional to eliminating of shoulder ballast.

The lateral strength of track also considerably augmented because of positive interlocking of the modular cages containing well compacted ballast coupled with the L-shaped/T-shaped cages firmly butting against the ends, provide many orders more resistance as compared to loose ballast, enhance the lateral as well as longitudinal resistance. This improves the safety of track against buckling under thermal loads. Particularly the trapezoidal modular element of cage with shorter side below and the larger side up, resisting on the sleepers longitudinal sides, expert positive vertical load to add to resistance of the track to lift, which is essential to prevent buckling.

The cage may be made of galvanized wires of sufficient strength to hold the ballast with edges reinforced with thicker diameter steel roads to keep the desire shape for the module.

BASIC SPECIFICATION

The sleeper vibrating at 150 to 250 Hz pound the ballast bed in normal conventional track. As the mass of ballast now is materially modified into modules of 80Kg+, Response frequency 0.39Hz is achieve at the foundation level.

So instead of starting with having to respond to 100Hz plus frequency at sleeper/ballast interface the first module of caged ballast will damp the frequency down to less than 0.5 Hz by the time it reaches the ballast modulus over which it is resting.

ADVANTAGES

1) The weight of each modular element is kept about 65 to 80 Kg each and the inertia of this mass will be enough to damp the vibrations, and every train which passes on track will only be stabilizing rather than de-stabilize the track.

2) Owing to the two above conditions, once the track is given proper geometry in line and level, running of trains will not disturb the track but it gets self-stabilized requiring no major maintenance of the nature required for loss ballast supported conventional track.

3) Both safety and economy to society are thus achieved, when better geometry to track is maintained without getting disturbed under traffic, without getting disturbed under traffic, without require the heavy track tamping machines.

4) The modular steel cages holding ballast precomppacted, will also provide better stability to track in the lateral direction as well ass in thee vertical direction, because of positive interlocking between the modules having the wire meshes, ass compared to losses ballast, and so track safety against buckling also tremendously improves.

5) If ballast gets dirty with dust and drainage is likely to be affected, a simple industrial grade portable vacuum cleaner will be suck out and clean the ballast, because the cage will prevent ballast being sucked out, allowing only the dust to be removed.

6) In case of accident restoring of track, the modular cages help in very quick construction of track and opening of track for traffic.

7) The ballast which is now expensive, will be saved to the extent of 70% in initial construction of track, as the middle one third of track will not require ballast as well ass the shoulders also will require less ballast. This also has further savings that annual recoupment for crushed and damaged ballast, of the order of 5% recurring will also be drastically reduced.

8) Because of the flexible construction using the modular cages, allowing for geometry correction for track, the self stabilizing track ass proposed, will be adaptable on all types of formations with considerable recurring saving in maintenance costs and improve safety.

9) For maintenance of SS track, the blocks stopping train movement, will be not required, thus releasing almost 10% of the line capacity earlier being lost in track maintenance.

CONCLUSION

From the above discussion, it is cleared that the new technique which is developed by Konkan Railway, is realy very effective. It not only serves the economy problem but also saving the ballast value and it prevents the serious accident problems, which is worst in railway transportation. The new trend in the railway construction is realy praiseworthy.

REFERENCES

1.Konkan railway corporation LTD: patented application, 900/MOM/2001 Dt. 118/09/2001.

2.Railway construction: N. Shadrin, S.Ulrikh, L.Perelman, A. Reoryeeev, I.Smagin, G.Leib.

3.Railway track: K. F. Antia.

4.Railroad construction: W.L.Waable.

5.Permanent way material: W. H. Cole.

6.a text book of railway engineering:R. S. Deshpande.

7.Railway: T. D. Ahuja, and G.S. Birdi.

8.Indian railway standard track management:- Indian railway board.

9. Indian Govt. railway coad for the engineering department.

CONTENTS

S. No.

Description

Pg. No.1. Abstract

1

2. Introduction

2

3. History of Railway

3

4. Development of railways in India

4

5. Component of permanent way

5

6. Self Stabilizing Track

11

7. Basic specification

15

8. Advantages

16

9. Conclusion

1810. References

19

CONTENT

1. Introduction

2. History of Railway.

3. Development of Railway in India.

4. Components of permanent way.

A. Ballast

B.Sleepers

IWooden sleepers

IISteel sleepers

IIICast iron sleepers

IVRCC sleepers

VPrestressed concrete sleepers

C. Rails

5. Self Stabilizing Track

6. Basic specification

7. Advantages

8. Conclusion

9. Reference

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