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Modern Methods of Track Maintenance

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Mechanized Methods of TrackMaintenance• The need to switch over from manual to mechanmethods of track maintenance is progressively bfelt due to the following reasons.

• Beater packing is a very hard and strenuous job

• It is dicult to ensure the uniform uality of the comp

under the sleepers carried out by manual means•  The intensity of the pressure and shock that the ball

subjected to when the beater is being used is very hi

•  Trac densities! a"le loads! and speeds have increasconsiderably on Indian #ailways considerably in the rpast.

• The retention of the packing done via manual mainte

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•

 Manual maintenance is not much suited to the mode•  $ith the increase in trac density! the time availabl

between trains is becoming progressively short

• $hen a track is maintained manually! it takes considtime for it to get fully consolidated

•  Manual methods do not emphasize on the identi%catdefects and monitoring of the work being done

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•

&n railways! the mechanized maintenance of tranormally involves the use of mechanical tamperare used to tamp or pack the ballast. Mechanicatampers are generally of two types

• &'(track tamper

• &n(track tampers.

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&'(track tampers

•

&'(track tampers are portable and can be uickly taken o' thby just two people.

• These tampers work during the interval between the passageand do not reuire any trac blockage

• &'(track tampers are portable and can be uickly taken o' thby just two people.

•

 These tampers work during the interval between the passageand do not reuire any trac blockage.

• They consist of tools driven by compressed air! electricity! or

• There are generally two types of tampers

• )elf(contained tampers

• $orking from a common power unit.

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•

 Tampers may be vibratory or of the percussion tcombination of both.

• In the vibratory type! tamping is achieved by vibas well as by the weight of the tamper itself

• In percussion type. tamping is achieved by impa

blows.• The important o'(track tampers tried on Indian

#ailways are *obra tampers! +ackson tampers! )tampers! and ,ango tampers.

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-se of &'(track Tampers

•

&'(track tampers are placed diagonally under the rworked in pairs from the opposite sides of the sleeporder to ascertain the ma"imum consolidation of thballast.

•  -sing beaters! the ballast is %rst loosened around tseat in the crib for a length of /0 mm 12345 on eith

of the foot of the raft• The tamper is then inserted vertically and the tamp

blades are kept about 6/ to 200 mm away from theso that enough ballast is available between the two

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7imitations of &'(track Tampers

•  The maintenance of these tampers has been found to be e"tremely because of the non(availability of spare parts! which are mostly impo

• Transporting o'(track tampers along with their power units to the sitethe mid(section is uite problematic.89 #ailway :ngineering

• Tamping with o'(track tampers is very strenuous and a worker normafatigued after 80;0 minutes. The uality of work done after this duralikely to deteriorate.

• Intensive supervision is reuired to ensure the correct use of these tathat the work done is of the desired uality. This type of supervision bparticularly dicult in the mid(section.

• The uality of tracks maintained using tampers is not very high compthose maintained by manual methods.

• The use of o'(track tampers following deep screening and relaying wbeen found to be very unsuitable for the early restoration of normal s

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&n(track Tampers

•

&n(track tampers are self(propelled vehicles which facautomatic tamping of sleepers through the controls pin the operator0 to 80 t and cannot removed from the track. It is therefore vital that the wdone after putting up the necessary trac blocks.

• =owever! the tamper can be put o' the track using speuipment! provided that there are adeuate banke"tensions available.

• These tampers can automatically and simultaneousperform the tasks of lifting! aligning! levelling! and tam

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?rinciples of $orking of &n(trac Tampers•

 Tamping• @ligning the track

• 7evelling

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 Tamping

• Tamping is the most important application of tie tamping 1TT5

• Tamping consists of packing the ballast under the sleeper. Thisachieved by vibrating the ballast! thereby making it Auid! and compressing it by sueezing

• Tamping is done with the help of either 29 or 8> tamping toolsdepending upon whether single or double sleepers are to be ptime.

• Tamping is done by either the synchronous or the non(synchrosystem of vibration. In the synchronous system! the movementwo tamping tools on either side of a sleeper are similar andsimultaneous! synchronizing with each other. In the case of nosynchronous systems! the two tools work independently.

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@ligning the track

•

 The alignment of the track is corrected by the twsystem in the case of machines manufactured bMessrs ?lasser and Theurer. In this method! two of lengths > m and 2> m are taken and placed area between two rails! where they are stretchedparallel to the track and kept a certain distance

from each other.

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7evelling

•

7ongitudinal levels are corrected on the basis of principle of proportional levelling with the help otampers along with an infrared transmitter! a bophotocells.

• The distance between these three units is %"ed so arranged that any error in the longitudinal levreduced to one(%fth of its value

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uture of Track

Machines on Indian#ailways

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ICT#&D-TI&C

•

Indian #ailways is systematically introducing lowelded rails and concrete sleepers on high(speeand tie tamping machine is ideally suited for themaintenance of such tracks.

• =owever! the following points reuire specialconsideration for the successful implementationmechanical methods of maintenance on Indian#ailways.

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• Blocks @deuate time blocks of about 8 to hoursEday should be mavailable so as to make mechanized maintenance e'ective and eco

• Ballast cushion @ clean ballast cushion of a depth of about >0 cm be available below the sleeper bed of each track that is to be maintamechanically.

• Repair facilities @deuate facilities for repair and overhauling shouavailable at the site and in the workshop.

• Spare parts @ good stock of spares should be kept ready at hand tothat the machines are always in good working order.

• Training of sta The sta' employed for working the tie tamping mshould have thorough knowledge of the principles and method involworking. @ full(Aedged training school euipped with the necessary euipment should be made available to train the sta' hired for the mmaintenance of tracks.

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 Tier )ystem of Track Maintenan

•

$ith the introduction of concrete sleepers and otamping machines on Indian #ailways! three(tierof track maintenance is being adopted on all secnominated for mechanized maintenance. This syconsists of the following three tiers of trackmaintenance.

•  &n(track machines units 1&M-5

• Mobile maintenance units 1MM-5

• )ectional gang

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 Tier 2F &n(track machines unit

•

 The work of systematic mechanized maintenanctrack is done with help of heavy on(track machinwhich include tie tamping machines for plain trawell as points and crossings! shoulder ballast clemachines! ballast cleaning machines! ballastregulating machines! and dynamic track stab

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 Tier 2F &n(track machines unit

•

 These machines are used when the following tato be performed.• )ystematic tamping of plain track as well as of points

crossings

• Intermediate tamping of plain tracks as well as of poicrossings

• )houlder ballast cleaning! ballast pro%lingEredistributstabilization! periodical deep screening

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 Tier >F Mobile maintenance unit

• ?icking up of slacks and other related works are done wihelp of mobile maintenance units 1MM-5. The #ailways ukinds of MM-s whose functions are as listed below.

• MM-(2 1#ail(cum(road vehicle based5 &ne such unit is pto each ?$I in charge of a 0;/0 km long double line or km long single line with a view to carrying out the follow

•  Ceed(based spot tamping

• *asual renewal and repairs! e"cept planned renewalsH in situ r

• &verhauling of level crossings

• #eplacement of glued joints as well as rail cutting or drilling anchamfering

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 Tier >F Mobile maintenance unit

• ?ermanent repair of fractures

• *reep or gap adjustments involving the use of machidestressing of 7$#E*$#

• 7oadingEunloading of materials and other miscellaneofunctions

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 Tier 8F )ectional gangs

-nder the three(tier system of track maintenance the segangs are reuired to perform the following functions.

• ?atrolling of the track! namely! the keyman

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 Tier 8F )ectional gangs

•

 Minor cess repairs! cleaning of drains! and bo"inballast

• ?aying attention to loops

• *reep and gap adjustment not involving the usemachines

• *leaning of crib ballast for e'ective cross draina• ?re( and post(tamping attention

• @ssistance in the working of MM- and &M- as re

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 T#@*, #:C:$@7

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ICT#&D-*TI&C

• The dynamic impact of running trains causes heavy wtear of the track.

• It becomes necessary to rehabilitate or renew the traperiodically to ensure that it continues to be safe andecient.

• =eavy track renewals are carried out on Indian #ailw

every year to keep the track safe and in a good runncondition as well as to bring down the cost of maintemuch as possible.

• The cost of track renewals carried out on Indian #ailwinto several thousand million.

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 *lassi%cation of Track #enewal$orks

 Track renewals can be broadly classi%ed as under• *omplete track renewal

• Through rail renewal

• Through sleeper renewals 1renewal of the ballasthe provision of a full ballast cushion is also done

• *asual renewal

• ?rimary renewals

• )econdary renewals

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*riteria for #ail #enewals

 The need for rail renewal can be felt because of aof the following reasons.

• Incidences of rail fractures or failures

• $ear of rails

• Maintaining tracks at the prescribed standards

• )hortened service life of rails

• ?lan(based renewal

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Incidences of rail fractures orfailures• The most important factor as it have vital bearin

the safety of track.

• -ltrasonic test done and results scrutinized

• J per year! 20 J overall

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#ail renewals may also become necessary because"cessive wear. This wear can be of various typesresult of the following.

• 7imiting loss of section

 $ear of #ails

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$ear of #ails

• $ear due to corrosion

• Kertical wear

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$ear of #ails

• 7ateral wear

M i t i i T k t th ?

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Maintaining Tracks at the ?rescr)tandards There may be situations in which renewals become necessar

though the service life of a rail has not yet e"pired! due to locsuch as curves! steep gradients! high speeds! heavy a"le loadscabbing! and wear of rails that have the following adverse ethe track.

• ?oor running uality of track in spite of the e"tra maintenanengaged on the section.

• Disproportionate cost of maintaining the track under safe co

• ?oor condition of the rail due to hogging! battering! scabbinburn! etc. and other causes such as the e"cessive corrugatiorail and which make track maintenance dicult and uneconand a'ect riding uality.

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)hortened )ervice 7ife of #ails

• Due to the passage of moving loads! alternatingstresses are created in the rail section.

• The number of reversals in the stresses are directhe weight in gross million tonnes 1MT5 borne brails.

•

 The majority of rail fractures originate from fatigcracks! which develop after a rail has borne thethreshold MT approved for it.

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?lan(based #enewals

• ?lan(based renewals are planned with the objectmodernizing the track structure on selected routthe uickest possible time.

• It may sometimes involve a premature renewal otrack also.

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 Through )leeper #enewals

• Through sleeper renewals should be done when percentage of unserviceable sleepers is eual totrunk routesEmain lines and 8/J on branch lines