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DetailofderailedexpresspassengervehicleinPrague,CzechRepublic,in2007.
AderailedfreighttraininFarragut,Tennessee,in2002.
DerailmentFromWikipedia,thefreeencyclopedia
Aderailmentissaidtotakeplacewhenavehicle(forexampleatrain)runsoffitsrails.Thisdoesnotnecessarilymeanthatitleavesitstrack.Althoughmanyderailmentsareminor,allresultintemporarydisruptionoftheproperoperationoftherailwaysystem,andtheyarepotentiallyseriouslyhazardoustohumanhealthandsafety.Usually,thederailmentofatraincanbecausedbyacollisionwithanotherobject,themechanicalfailureoftracks,suchasbrokenrails,orthemechanicalfailureofthewheels.
Contents
1History2Causes
2.1Brokenrails2.2Defectivewheels2.3Unusualtrackinteraction2.4Improperoperationofcontrolsystems2.5Derailmentfollowingcollision2.6Harshtrainhandling2.7Flangeclimbing
2.7.1Wheelrailinteraction3Rerailing4Examples
4.1Primarymechanicalfailureofatrackcomponent4.2Primarymechanicalfailureofacomponentoftherunninggearofavehicle4.3Dynamiceffectsofvehicletrackinteraction4.4Improperoperationofcontrolsystems4.5Secondaryeventsfollowingcollision4.6Trainhandlingeffects4.7Geometryfaultsthatresultinquasistaticfailure
5Seealso6Notes7References8Furtherreading
History
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AderailedlocomotiveunitinAustraliainJanuary2007atacatchpointhiddenfromview.
Abrokenrail,probablystartingfromhydrogeninclusionintherailhead
Inthenineteenthcenturyderailmentswerecommonplace,butprogressivelyimprovedsafetymeasureshaveresultedinastablelowerlevelofsuchincidents.IntheUS,derailmentshavedroppeddramaticallysince1980fromover3,000annually(1980)to1,000orsoin1986,toabout500in2010.[1][2]
Causes
Derailmentsresultfromoneormoreofanumberofdistinctcausesthesemaybeclassifiedas:
theprimarymechanicalfailureofatrackcomponent(forexamplebrokenrails,gaugespreadduetosleeper(tie)failure)theprimarymechanicalfailureofacomponentoftherunninggearofavehicle(forexampleaxleboxfailure,wheelbreakage)afaultinthegeometryofthetrackcomponentsortherunninggearthatresultsinaquasistaticfailureinrunning(forexamplerailclimbingduetoexcessivewearofwheelsorrails,earthworksslip)adynamiceffectofthetrackvehicleinteraction(forexampleextremehunting,verticalbounce,trackshiftunderatrain,excessivespeed)improperoperationofpoints,orimproperobservanceofsignalsprotectingthem(signalerrors)asasecondaryeventfollowingcollisionwithothertrains,roadvehicles,orotherobstructions(levelcrossingcollisions,obstructionsontheline)trainhandling(snatchesduetosuddentractionorbrakingforces).
[note1]
Brokenrails
Atraditionaltrackstructureconsistsoftworails,fixedadesignateddistanceapart(knownasthetrackgauge),andsupportedontransversesleepers(ties).Someadvancedtrackstructuressupporttherailsonaconcreteorasphaltslab.Therunningsurfaceoftherailsisrequiredtobepracticallycontinuousandofthepropergeometricallayout.
Intheeventofabrokenorcrackedrail,therailrunningsurfacemaybedisruptedifapiecehasfallenout,orbecomelodgedinanincorrectlocation,orifalargegapbetweentheremainingrailsectionsarises.170broken(notcracked)railswerereportedonNetworkRailintheUKin2008,downfromapeakof988in1998/1999.
Injointedtrack,railsareusuallyconnectedwithboltedfishplates(jointbars).Theweboftherailexperienceslargeshearforcesandtheseareenhancedaroundthebolthole.Wheretrackmaintenanceispoor,metallurgicalfatiguecanresultinthepropagationofstarcrackingfromthebolthole.Inextremesituationsthiscanleadtoatriangularpieceofrailatthejointbecomingdetached.
Metallurgicalchangestakeplaceduetothephenomenonofgaugecornercracking(inwhichfatiguemicrocrackingpropagatesfaster
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thanordinarywear),andalsoduetotheeffectsofhydrogeninclusionduringthemanufacturingprocess,leadingtocrackpropagationunderfatigueloading.
Localembrittlementoftheparentmetalmaytakeplaceduetowheelspin(tractionunitsrotatingdrivingwheelswithoutmovementalongthetrack).
Railwelds(whererailsectionsarejoinedbywelding)mayfailduetopoorworkmanshipthismaybetriggeredbyextremelycoldweatherorimproperstressingofcontinuouslyweldedrails,suchthathightensileforcesaregeneratedintherails.
Thefishplates(jointbars)injointedtrackmayfail,allowingtherailstopullapartinextremelycoldweatherthisisusuallyassociatedwithuncorrectedrailcreep.
Derailmentmaytakeplaceduetoexcessivegaugewidening(sometimesknownasroadspread),inwhichthesleepersorotherfasteningsfailtomaintainthepropergauge.Inlightlyengineeredtrackwhererailsarespiked(dogged)totimbersleepers,spikeholdfailuremayresultinrotationoutwardsofarail,usuallyundertheaggravatingactionofcrabbingofbogies(trucks)oncurves.[2]
Themechanismofgaugewideningisusuallygradualandrelativelyslow,butifitisundetected,thefinalfailureoftentakesplaceundertheeffectofsomeadditionalfactor,suchasexcessspeed,poorlymaintainedrunninggearonavehicle,misalignmentofrails,andextremetractioneffects(suchashighpropellingforces).Thecrabbingeffectreferredtoaboveismoremarkedindryconditions,whenthecoefficientoffrictionatthewheeltorailinterfaceishigh.
Defectivewheels
Therunninggearwheelsets,bogies(trucks),andsuspensionmayfail.Themostcommonhistoricalfailuremodeiscollapseofplainbearingsduetodeficientlubrication,andfailureofleafspringswheeltyresarealsopronetofailureduetometallurgicalcrackpropagation.
Moderntechnologieshavereducedtheincidenceofthesefailuresconsiderably,bothbydesign(speciallytheeliminationofplainbearings)andintervention(nondestructivetestinginservice).
Unusualtrackinteraction
Ifavertical,lateral,orcrosslevelirregularityiscyclicandtakesplaceatawavelengthcorrespondingtothenaturalfrequencyofcertainvehiclestraversingtheroutesection,thereisariskofresonantharmonicoscillationinthevehicles,leadingtoextremeimpropermovementandpossiblyderailment.Thisismosthazardouswhenacyclicrollissetupbycrosslevelvariations,butverticalcyclicalerrorsalsocanresultinvehiclesliftingoffthetrackthisisespeciallythecasewhenthevehiclesareinthetare(empty)condition,andifthesuspensionisnotdesignedtohaveappropriatecharacteristics.Thelastconditionappliesifthesuspensionspringinghasastiffnessoptimisedfortheloadedcondition,orforacompromiseloadingcondition,sothatitistoostiffinthetaresituation.
Thevehiclewheelsetsbecomemomentarilyunloadedverticallysothattheguidancerequiredfromtheflangesorwheeltreadcontactisinadequate.
Aspecialcaseisheatrelatedbuckling:inhotweathertherailsteelexpands.Thisismanagedbystressingcontinuouslyweldedrails(theyaretensionedmechanicallytobestressneutralatamoderatetemperature)andbyprovidingproperexpansiongapsatjointsandensuringthatfishplatesareproperlylubricated.Inaddition,lateral
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restraintisprovidedbyanadequateballastshoulder.Ifanyofthesemeasuresareinadequate,thetrackmaybucklealargelateraldistortiontakesplace,whichtrainsareunabletonegotiate.(Innineyears2000/1to2008/9therewere429trackbuckleincidentsinGreatBritain).[note2][3]
Improperoperationofcontrolsystems
Junctionsandotherchangesofroutingonrailwaysaregenerallymadebymeansofpoints(switchesmovablesectionscapableofchangingtheonwardrouteofvehicles).Intheearlydaysofrailwaystheseweremovedindependentlybylocalstaff.Accidentsusuallycollisionstookplacewhenstaffforgotwhichroutethepointsweresetfor,oroverlookedtheapproachofatrainonaconflictingroute.Ifthepointswerenotcorrectlysetforeitherroutesetinmidstrokeitispossibleforatrainpassingtoderail.
ThefirstconcentrationofleversforsignalsandpointsbroughttogetherforoperationwasatBricklayer'sArmsJunctioninsoutheastLondonintheperiod18431844.Thesignalcontrollocation(forerunnerofthesignalbox)wasenhancedbytheprovisionofinterlocking(preventingaclearsignalbeingsetforaroutethatwasnotavailable)in1856.[4]
Topreventtheunintendedmovementoffreightvehiclesfromsidingstorunninglines,andotheranalogousimpropermovements,trappointsandderailsareprovidedattheexitfromthesidings.Insomecasestheseareprovidedattheconvergenceofrunninglines.Itoccasionallyhappensthatadriverincorrectlybelievess/hehasauthoritytoproceedoverthetrappoints,orthatthesignallerimproperlygivessuchpermissionthisresultsinderailment.Theresultingderailmentdoesnotalwaysfullyprotecttheotherline:atrappointderailmentatspeedmaywellresultinconsiderabledamageandobstruction,andevenasinglevehiclemayobstructtheclearline.
Derailmentfollowingcollision
Ifatraincollideswithamassiveobject,itisclearthatderailmentoftheproperrunningofvehiclewheelsonthetrackmaytakeplace.Althoughverylargeobstructionsareimagined,ithasbeenknownforacowstrayingontothelinetoderailapassengertrainatspeed.
Themostcommonobstructionsencounteredareroadvehiclesatlevelcrossings(gradecrossings)maliciouspersonssometimesplacematerialsontherails,andinsomecasesrelativelysmallobjectscauseaderailmentbyguidingonewheelovertherail(ratherthanbygrosscollision).
Derailmenthasalsobeenbroughtaboutinsituationsofwarorotherconflict,suchasduringhostilitybynativeAmericans,andmoreespeciallyduringperiodswhenmilitarypersonnelandmaterielwasbeingmovedbyrail.[5][6][7]
Harshtrainhandling
Thehandlingofatraincanalsocausederailments.Thevehiclesofatrainareconnectedbycouplingsintheearlydaysofrailwaysthesewereshortlengthsofchain("loosecouplings")thatconnectedadjacentvehicleswithconsiderableslack.Evenwithlaterimprovementstheremaybeaconsiderableslackbetweenthetractionsituation(powerunitpullingthecouplingstight),andpowerunitbraking(locomotiveapplyingbrakesandcompressingbuffersthroughoutthetrain).Thisresultsincouplingsurge.
Moresophisticatedtechnologiesinusenowadaysgenerallyemploycouplingsthathavenolooseslack,althoughthereiselasticmovementatthecouplingscontinuousbrakingisprovided,sothateveryvehicleonthetrainhasbrakescontrolledbythedriver.Generallythisusescompressedairasacontrolmedium,andthereisameasurabletimelagasthesignal(toapplyorreleasebrakes)propagatesalongthetrain.
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Ifatraindriverappliesthetrainbrakessuddenlyandseverely,thefrontpartofthetrainissubjecttobrakingforcesfirst.(Whereonlythelocomotivehasbraking,thiseffectisobviouslymoreextreme).Therearpartofthetrainmayoverrunthefrontpart,andincaseswherecouplingconditionisimperfect,theresultantsuddenclosingupmayresultinavehicleintarecondition(anemptyfreightvehicle)beingliftedmomentarily,andleavingthetrack.
Thiseffectwasrelativelycommoninthenineteenthcentury.[8]
Oncurvedsections,thelongitudinal(tractionorbraking)forcesbetweenvehicleshaveacomponentinwardoroutwardrespectivelyonthecurve.Inextremesituationstheselateralforcesmaybeenoughtoencouragederailment.
Aspecialcaseoftrainhandlingproblemsisoverspeedonsharpcurves.Thisgenerallyariseswhenadriverfailstoslowthetrainforasharpcurvedsectioninaroutethatotherwisehashigherspeedconditions.Intheextremethisresultsinthetrainenteringacurveataspeedatwhichitcannotnegotiatethecurve,andgrossderailmenttakesplace.Thespecificmechanismofthismayinvolvebodilytipping(rotation)butislikelytoinvolvedisruptionofthetrackstructureandderailmentastheprimaryfailureevent,followedbyoverturning.
Flangeclimbing
Theguidancesystemofpracticalrailwayvehiclesreliesonthesteeringeffectoftheconicityofthewheeltreadsonmoderatecurves(downtoaradiusofabout500m,orabout1,500feet).Onsharpercurvesflangecontacttakesplace,andtheguidingeffectoftheflangereliesonaverticalforce(thevehicleweight).
Aflangeclimbingderailmentcanresultiftherelationshipbetweentheseforces,L/V,isexcessive.ThelateralforceLresultsnotonlyfromcentrifugaleffects,butalargecomponentisfromthecrabbingofawheelsetwhichhasanonzeroangleofattackduringrunningwithflangecontact.TheL/Vexcesscanresultfromwheelunloading,orfromimproperrailorwheeltreadprofiles.Thephysicsofthisismorefullydescribedbelow,inthesectionwheelrailinteraction.
Wheelunloadingcanbecausedbytwistinthetrack.Thiscanariseifthecant(crosslevel,orsuperelevation)ofthetrackvariesconsiderablyoverthewheelbaseofavehicle,andthevehiclesuspensionisverystiffintorsion.Inthequasistaticsituationitmayariseinextremecasesofpoorloaddistribution,oronextremecantatlowspeed.
Ifarailhasbeensubjecttoextremesidewear,orawheelflangehasbeenworntoanimproperangle,itispossiblefortheL/Vratiotoexceedthevaluethattheflangeanglecanresist.
Ifweldrepairofsidewornswitchesisundertaken,itispossibleforpoorworkmanshiptoproducearampintheprofileinthefacingdirection,thatdeflectsanapproachingwheelflangeontotherailhead.
Inextremesituations,theinfrastructuremaybegrosslydistortedorevenabsentthismayarisefromearthworksmovement(embankmentslipsandwashouts),earthquakeandothermajorterrestrialdisruption,deficientprotectionduringworkprocessesetc.
Wheelrailinteraction
Nearlyallpracticalrailwaysystemsusewheelsfixedtoacommonaxle:thewheelsonbothsidesrotateinunison.Tramcarsrequiringlowfloorlevelsaretheexception,butmuchbenefitinvehicleguidanceislostbyhavingunlinkedwheels.[9]
Thebenefitoflinkedwheelsderivesfromtheconicityofthewheeltreadsthewheeltreadsarenotcylindrical,butconical.[1][9]Onidealisedstraighttrack,awheelsetwouldruncentrally,midwaybetweentherails.
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Theexampleshownhereusesarightcurvingsectionoftrack.Thefocusisontheleftsidewheel,whichismoreinvolvedwiththeforcescriticaltoguidingtherailcarthroughthecurve.
Diagram1belowshowsthewheelandrailwiththewheelsetrunningstraightandcentralonthetrack.Thewheelsetisrunningawayfromtheobserver.(Notethattherailisshowninclinedinwardsthisisdoneonmoderntracktomatchtherailheadprofiletothewheeltreadprofile.)
Diagram2showsthewheelsetdisplacedtotheleft,duetocurvatureofthetrackorageometricalirregularity.Theleftwheel(shownhere)isnowrunningonaslightlylargerdiametertherightwheeloppositehasmovedtotheleftaswell,towardsthecentreofthetrack,andisrunningonaslightlysmallerdiameter.Asthetwowheelsrotateatthesamerate,theforwardspeedoftheleftwheelisalittlefasterthantheforwardspeedoftherightwheel.Thiscausesthewheelsettocurvetotheright,correctingthedisplacement.Thistakesplacewithoutflangecontactthewheelsetssteerthemselvesonmoderatecurveswithoutanyflangecontact.
Thesharperthecurve,thegreaterthelateraldisplacementnecessarytoachievethecurving.Onaverysharpcurve(typicallylessthanabout500mor1,500feetradius)thewidthofthewheeltreadisnotenoughtoachievethenecessarysteeringeffect,andthewheelflangecontactsthefaceofthehighrail.[note3]
Diagram3showstherunningofwheelsetsinabogieorafourwheeledvehicle.Thewheelsetisnotrunningparalleltothetrack:itisconstrainedbythebogieframeandsuspension,anditisyawingtotheoutsideofthecurvethatis,itsnaturalrollingdirectionwouldleadalongalesssharplycurvedpaththantheactualcurveofthetrack.[note4]
Theanglebetweenthenaturalpathandtheactualpathiscalledtheangleofattack(ortheyawangle).Asthewheelsetrollsforward,itisforcedtoslideacrosstherailheadbytheflangecontact.Thewholewheelsetisforcedtodothis,sothewheelonthelowrailisalsoforcedtoslideacrossitsrail.[note5]
Thisslidingrequiresaconsiderableforcetomakeithappen,andthefrictionforceresistingtheslidingisdesignated"L",thelateralforce.ThewheelsetappliesaforceLoutwardstotherails,andtherailsapplyaforceLinwardstothewheels.Notethatthisisquiteindependentof"centrifugalforce".[note6]HoweverathigherspeedsthecentrifugalforceisaddedtothefrictionforcetomakeL.
Theload(verticalforce)ontheouterwheelisdesignatedV,sothatindiagram4thetwoforcesLandVareshown.
Thesteeltosteelcontacthasacoefficientoffrictionthatmaybeashighas0.5indryconditions,sothatthelateralforcemaybeupto0.5oftheverticalwheelload.[note7]
Duringthisflangecontact,thewheelonthehighrailisexperiencingthelateralforceL,towardstheoutsideofthecurve.Asthewheelrotates,theflangetendstoclimbuptheflangeangle.ItishelddownbytheverticalloadonthewheelV,sothatifL/Vexceedsthetrigonometricaltangentoftheflangecontactangle,climbingwilltakeplace.Thewheelflangewillclimbtotherailheadwherethereisnolateralresistanceinrollingmovement,andaflangeclimbingderailmentusuallytakesplace.Indiagram5theflangecontactangleisquitesteep,andflangeclimbingisunlikely.Howeveriftherailheadissideworn(sidecut)ortheflangeisworn,asshownindiagram6thecontactangleismuchflatterandflangeclimbingismorelikely.[2][9]
Oncethewheelflangehascompletelyclimbedontotherailhead,thereisnolateralrestraint,andthewheelsetislikelytofollowtheyawangle,resultinginthewheeldroppingoutsidetherail.AnL/Vratiogreaterthan0.6isconsideredtobehazardous.[1]
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Diagram1:Wheeltreadandrailduringcentralrunning
Diagram2:Wheelandrailwithwheeldisplacedtotheleft
Diagram3:Bogieandwheelsetinarightturningcurve
Diagram4:LandVforcesincurving
Diagram5:Wheelandrailduringflangeclimbing
Diagram6:Wornwheelandrailduringflangeclimbing
Aderailedsteamlocomotivebeingliftedbackontothetracksbyarailmountedcranein1951
Itisemphasisedthatthisisamuchsimplifieddescriptionofthephysicscomplicatingfactorsarecreep,actualwheelandrailprofiles,dynamiceffects,stiffnessoflongitudinalrestraintataxleboxes,andthelateralcomponentoflongitudinal(tractionandbraking)forces.[8]
Wheelrailinteractions
Rerailing
Followingaderailment,itisnaturallynecessarytoreplacethevehicleonthetrack.Ifthereisnosignificanttrackdamagethatmaybeallthatisneeded.Howeverwhentrainsinnormalrunningderailatspeed,aconsiderablelengthoftrackmaybedamagedordestroyedfarworsesecondarydamagemaybecausedifabridgeisencountered.
Withsimplewagonderailmentswherethefinalpositionisclosetothepropertracklocation,itisusuallypossibletopullthederailedwheelsetsbackontothetrackusingrerailingrampsthesearemetalblocksdesignedtofitovertherailsandtoprovidearisingpathbacktothetrack.Alocomotiveisusuallyusedtopullthewagon.
Ifthederailedvehicleisfurtherfromthetrack,oritsconfiguration(suchasahighcentreofgravityoraveryshortwheelbase)maketheuseoframpsimpossible,jacksmaybeused.Initscrudestform,theprocessinvolvesliftingthevehicleframeandthenallowingittofalloffthejacktowardsthetrack.Thismayneedtoberepeated.
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Rerailingalocomotiveusingarerailerandwoodenblocksafterabrokenrailderailment
Amoresophisticatedprocessinvolvesacontrolledprocessusingslewingjacksinaddition.Photographsofearlylocomotivesoftenindicateoneormorejackscarriedontheframeofthelocomotiveforthepurpose,presumedtobeafrequentoccurrence.
Whenmorecomplexrerailingworkisneeded,variouscombinationsofcableandpulleysystemsmaybeused,ortheuseofoneormorerailbornecranestoliftalocomotivebodily.[10][11]Inspecialcasesroadcranesareused,asthesehavegreaterliftingandreachcapacity,ifroadaccesstothesiteisfeasible.
Intheextreme,aderailedvehicleinanawkwardlocationmaybescrappedandcutuponsite,orsimplyabandonedasnonsalvageable.
Examples
Note:thereisalargelistofrailwayaccidentsingeneralatListsofrailaccidents.
Primarymechanicalfailureofatrackcomponent
IntheHatfieldrailcrashinEnglandin2000,rollingcontactfatiguehadresultedinmultiplegaugecornercrackinginthesurface300suchcracksweresubsequentlyfoundatthesite.Therailcrackedunderahighspeedpassengertrain,whichderailed.Fourpersonsdied.[12]
IntheearlierHitherGreenrailcrash,atriangularsegmentofrailatajointbecamedisplaced,andlodgedinthejointitderailedapassengertrainand49personsdied.Poormaintenanceonanintensivelyoperatedsectionofroutewasthecause.[13]
Primarymechanicalfailureofacomponentoftherunninggearofavehicle
AtEschedeinLowerSaxony,Germanyahighspeedpassengertrainbecamederailedin1998,and101peopledied.Theprimarycausewasthefracturefrommetalfatigueofawheeltyrethetrainfailedtonegotiatetwosetsofpointsandstruckthepierofanoverbridge.ItwasthemostseriousrailwayaccidentinGermany,andalsothemostseriousonanyhighspeed(over200kilometresperhour(120mph))line.Ultrasonictestinghadfailedtorevealtheincipientfracture.[14]SeeEschedetraindisaster.
Dynamiceffectsofvehicletrackinteraction
In1967intheUKtherewerefourderailmentsduetobucklingofcontinuouslyweldedtrack("cwr"):atLichfieldon10June,anemptycarflattrain(atrainofflatcarsfortransportingautomobiles)on13JuneanexpresspassengertrainwasderailedatSomertonon15Julyafreightlinertrain(containertrain)wasderailedatLamingtonandon23JulyanexpresspassengertrainwasderailedatSandy.Theofficialreportwasnotentirelyconclusiveastothecauses,butitobservedthattheannualtotalofbucklingdistortionswas48in1969,havingbeeninsinglefiguresineverypreviousyear,andthat[heatrelated]distortionsper1,000milesperannumwere10.42forcwrand2.98forjointedtrackin1969,havingbeenamaximumof1.78and1.21intheprevioustenyears.90%ofthedistortionscouldbeattributedtooneofthefollowing:
failuretocomplywiththeinstructionsforlayingormaintainingcwrtrackrecentinterferencewiththeconsolidationoftheballasttheeffectofdiscontinuitiesinthecwrtracksuchaspointsetc.
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Thislocomotivewasderailedbythe1906SanFranciscoearthquake.Thelocomotivehadthreelinkandpincouplerpocketsformovingstandardandnarrowgaugecars.
extraneousfactorssuchasformationsubsidence.[15]
Improperoperationofcontrolsystems
IntheConningtonSouthrailcrashon5March1967inEngland,asignallermovedthepointsimmediatelyinfrontofanapproachingtrain.Mechanicalsignallingwasinforceatthelocation,anditwasbelievedthatheimproperlyreplacedthesignalprotectingthepointstodangerjustasthelocomotivepassedit.Thisreleasedthelockingonthepointsandhemovedthemtoleadtoalooplinewithalowspeedrestriction.Thetrain,travellingat75milesperhour(121km/h),wasunabletonegotiatethepointsinthatpositionandfivepersonsdied.Thesignallerhadseenarmyserviceandwasprobablysufferingfromwhatisnowcalledposttraumaticstresssyndrome.[16]
Secondaryeventsfollowingcollision
ApassengertrainwasderailedinthePolmontrailaccidentintheUKin1984uponhittingacowatspeedthetrainformationhadthelocomotiveattherear(propelling)withalightdrivingtrailervehicleleading.Thecowhadstrayedontothelinefromadjacentagriculturalland,duetodeficientfencing.13personsdiedintheresultingderailment.[17]Howeverthiswasthoughttobethefirstoccurrencefromthiscause(intheUK)since1948.[18]
Trainhandlingeffects
TheSalisburyrailcrashtookplaceon1July1906afirstclassonlyspecialboattrainfromStonehousepool,PlymouthEngland,ranthroughSalisburystationatabout60milesperhour(97km/h)therewasasharpcurveoftenchains(660feet,200m)radiusandaspeedrestrictionto30milesperhour(48km/h).Thelocomotiveoverturnedbodilyandstruckthevehiclesofamilktrainontheadjacentline.28peoplewerekilled.Thedriverwassoberandnormallyreliable,buthadnotdrivenanonstoppingtrainthroughSalisburybefore.[19]
TherehavebeenseveralotherderailmentsintheUKduetotrainsenteringspeedrestrictedsectionsoftrackatexcessivespeedthecauseshavegenerallybeeninattentionbythedriverduetoalcohol,fatigueorothercauses.ProminentcasesweretheNuneatonrailcrashin1975(temporaryspeedrestrictioninforceduetotrackwork,warningsignilluminationfailed),[20]theMorpethaccidentin1984(expresspassengersleepingcartraintook50milesperhour(80km/h)restrictedsharpcurveatfullspeedalcoholafactornofatalitiesduetotheimprovedcrashworthinessofthevehicles)[21]
Geometryfaultsthatresultinquasistaticfailure
Seealso
ListsofrailaccidentsTrainwreckTramaccidentGuardrails
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Notes
References
1. ^TheU.S.FederalRailroadAdministrationcategorisesderailmentsdifferently,fortheuseofprofessionalsintheindustrythesearenotcompletelyhelpfulforexternalreaders,butforcompleteness,themaingroupingsaregivenhere:
Rail,jointbarandanchoringTrackgeometrydefectGeneralswitchingrulesWheelsAxlesandjournalbearingsSwitchesFrogs,switchesandtrackappliancesBogiecomponentsTrainhandling/trainmakeupHighwayrailgrading
Source:SafetyDatabaseAnalysis,TransportationTechnologyCenterInc,PuebloCol,2002,quotedinWuandWilson,page210211
2. ^OnNetworkRail,soexcludingcertain"Metro"networks.3. ^Thehighrailisconsideredtobetheouterrailinacurvethelowrailistheinnerrail.4. ^Yawdescribesthesituationwhenthelongitudinalaxisofthewheelsetisnotthesameasthelongitudinalaxisof
motion.5. ^Thiswasunderstoodasearlyas1844,whenRobertStephensongaveevidencethat"inbringingroundthecurve,the
wheelswillallbefixedontheaxles,andbeingofthesamesize,ofcoursetheoutsidehastogoovermoregroundthantheinsideandthereforetheoutsideonesslideupontheturn,andconsequently,asyouseeintheBristolstations[wherebroadgaugetrainswerenegotiatingsharpcurves],youwillseesuchwheelsgrindintheiroperation."StephensonwasgivingevidenceintheHouseofCommonsregardingtheSouthDevonRailwaybill,on26April1844,quotedinHughHowes,TheStrugglefortheSouthDevonRailway,TwelveheadsPress,Chacewater,2012,ISBN9780906294741
6. ^Centrifugalforceisaconvenientimaginaryconceptstrictlyspeakingitistheinertiaofabodybeingaccelerated,equaltotheproductofthemassofthebodyandtheacceleration.
7. ^ThevalueofLisdeterminedbytheloadonbothwheelsofthewheelsetmultipliedbythecoefficientoffriction,plusthecentrifugalforce.Buttheslidingonthewheelonthelowrailisnotlateralthewheeltreadisactuallyslidingbackwards(i.erotatinglessrapidlythantheforwardspeedrequires)andthelateralfrictionforcegeneratedislimitedbythevectoroftheslidingaction.
1. ^abcGeorgeDBibel,TrainWrecktheForensicsofRailDisasters,HopkinsUniversityPress,Baltimore,2012,ISBN9781421405902
2. ^abcHuiminWuandNicholasWilson,RailwayVehicleDerailmentandPrevention,inHandbookofRailwayVehicleDynamics
3. ^RailAccidentInvestigationBoard(UK),DerailmentofaTrainatCummersdale,Cumbria,1June2009,Derby,England,2010
4. ^BrianSolomon,RailroadSignaling,VoyageurPress,Minneapolis,MN,2003,ISBN97807603136025. ^DonDeNeviandBobHall,UnitedStatesMilitaryRailwayServiceAmerica'sSoldierRailroadersinWWII,1992,
BostonMillsPress,Erin,Ontario,ISBN1550460218.6. ^ChristianWolmar,EnginesOfWar:HowWarsWereWon&LostOnTheRailways,AtlanticBooks,2010,ISBN
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Furtherreading
Iwnicki,Simon,ed.(2006).HandbookofRailwayVehicleDynamics.BocaRaton,Fl:TaylorandFrancis.ISBN9780849333217.
Retrievedfrom"http://en.wikipedia.org/w/index.php?title=Derailment&oldid=646633464"
Categories: Railwayaccidents Railtechnologies
Thispagewaslastmodifiedon11February2015,at11:17.TextisavailableundertheCreativeCommonsAttributionShareAlikeLicenseadditionaltermsmay
6. ^ChristianWolmar,EnginesOfWar:HowWarsWereWon&LostOnTheRailways,AtlanticBooks,2010,ISBN9781848871724
7. ^AmericanExperience:NativeAmericansandtheTranscontinentalRailroad(http://www.pbs.org/wgbh/americanexperience/features/generalarticle/tcrrtribes/)
8. ^abColinCole,LongitudinalTrainDynamics,inHandbookofRailwayVehicleDynamics
9. ^abcJeanBernardAyasseandHuguesChollet,WheelRailContact,inHandbookofRailwayDynamics10. ^PeterTatlow,RailwayBreakdownCranes:Volume1,NoodleBooks,2012,ISBN978190641969111. ^PeterTatlow,RailwayBreakdownCranes:Volume2,NoodleBooks,2013,ISBN978190641997412. ^OfficeofRailRegulation,TrainDerailmentatHatfield:AFinalReportbytheIndependentInvestigationBoard,
London,2006,at[1](http://www.railreg.gov.uk/upload/pdf/297.pdf)13. ^MinistryofTransport,ReportontheDerailmentthatOccurredon5thNovember1967atHitherGreeninthe
SouthernRegionofBritishRailways,HerMajesty'sStationeryOffice,London,1968,at[2](http://www.railwaysarchive.co.uk/docsummary.php?docID=99)
14. ^ErichPreu,Eschede,10Uhr59.DieGeschichteeinerEisenbahnKatastrophe,GeraNovaZeitschriftenverlag,2002,ISBN3932785215
15. ^MajorCFRose,RailwayAccidents,InterimReportontheDerailmentsthatoccurredonContinuousWeldedTrackatLichfield(LondonMidlandRegion),Somerton(WesternRegion)andSandy(EasternRegion),BritishRailways,duringJuneandJuly1969,andontheGeneralSafetyofthisformofTrack,HerMajesty'sStationeryOffice,London,1970,at[3](http://www.railwaysarchive.co.uk/docsummary.php?docID=1272)
16. ^LtColIKAMcNaughton,ReportontheDerailmentthatOccurredon5thMarch,1967,atConningtonSouthintheEasternRegionBritishRailways,HerMajesty'sStationeryOffice,London,1969,ISBN0115500790,athttp://www.railwaysarchive.co.uk/documents/MoT_Connington1967.pdf
17. ^HerMajesty'sRailwayInspectorate,ReportontheDerailmentthatoccurredon30thJuly1984nearPolmontintheScottishRegion,BritishRailways,HerMajesty'sStationeryOffice,1985,ISBN0115506853
18. ^HerMajesty'sRailwayInspectorate,RailwaySafety:ReportontheSafetyRecordoftheRailwaysinGreatBritainDuring1984,HerMajesty'sStationeryOffice,London,1984
19. ^MajorJWPringle,ReportfortheBoardofTrade,London,31July1906,at[4](http://www.railwaysarchive.co.uk/documents/BoT_Salisbury1906.pdf)
20. ^HerMajesty'sRailwayInspectorate,ReportontheDerailmentthatoccurredon6thJune1985atNuneatonintheLondonMidlandRegionofBritishRailways,HerMajesty'sStationeryOffice,1986
21. ^HerMajesty'sRailwayInspectorate,ReportontheDerailmentthatoccurredon24thJune1984atMorpethintheEasternRegionofBritishRailways,HerMajesty'sStationeryOffice,1985
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