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FrontalOffsetCrashworthinessEvaluationGuidelinesforRatingInjuryMeasuresMay2004FrontalOffsetCrashworthinessEvaluationGuidelinesforRatingInjuryMeasuresInjurymeasuresobtainedfromaninstrumented50thpercentilemaleHybridIIIdummyinthedriverseatareusedtodeterminethelikelihoodthatanoccupantwouldhavesustainedsignificantinjurytovariousbodyregions.Twenty-eightdifferentmeasuresarerecordedineachoftheInstitute’sfrontaloffsetcrashtests:•headacceleration(threedirectionsfromhead’scenterofgravity)•axialforce,anterior-posteriorforce,andanterior-posteriorbendingmomentactingattheconnectionbetweenthedummy’sheadandneck•thoracicspineacceleration(threedirections)•sternumcompression•femuraxialforce(eachleg)•tibia-femurdisplacement(eachleg)•tibiatransversebendingmoments(upperandlower,eachleg)•tibiaaxialforce(eachleg)•footacceleration(twodirections,eachfoot)The28measuresaregroupedintofourbodyregions:headandneck,chest,leftlegandfoot,andrightlegandfoot.Fourinjuryparametersareusedtoevaluateprotectionfortheheadandneck,threeparametersforthechest,andsixparametersforeachlegandfoot.Eachbodyregionreceivesaninjuryprotectionratingofgood,acceptable,marginal,orpoorbasedontheinjuryparametersforthatregion.Foranybodyregiontoreceiveagoodrating,thescoresforallinjuryparametersinthatregionmustindicategoodresults.Ifanyparameterindicatesanacceptableresult,thentheratingforthatbodyregionisacceptable.Ifanyparameterhasamarginalresult,thentheratingforthatbodyregionismarginal.Thustheoverallinjuryratingforanybodyregionisthelowestratingscoredforaninjuryparameterwithinthatregion.Table1showstheinjuryparameterrangesassociatedwiththepossibleratings:good,acceptable,marginal,andpoor.InjuryresultsthatroundtothevaluesshowninTable1willreceivethebetterofthetworatingstheyseparate.Withsomeexceptions(e.g.,chestacceleration),thebordersbetweenacceptableandmarginalratingsforagiveninjuryparametercorrespondtopublishedinjuryassessmentreferencevalues(IARV)forsignificantinjuryrelatedtothatparameter.Acceptableratingscorrespondtomeasuressomewhatbelow(betterthan)theIARVs,andgoodratingscorrespondtomeasureswellbelowtheIARVs.Similarly,marginalratingscorrespondtomeasuresjustabove(worsethan)theIARVs,andpoorratingscorrespondtomeasureswellabovetheIARVs.ItisimportanttorememberinreadingTable1thatcrashesarecomplexevents.Itisnotpossibleforaninjury-codingschemetoforeseeallthepossiblecombinationsofoutcomesthatcouldsuggestinjuryriskinacrash.Therefore,theinformationinTable1shouldbeinterpretedasprovidingguidelinesforevaluatingdummyinjurymeasures,whicharealwayssubjecttomodificationbasedonthecircumstancesoftheparticularcrashtestandonnewbiomechanicalinformationaboutinjurytolerance.IARVsarebasedoncurrentbiomechanicalinformationabouthumaninjurymechanismsandaredescribedinmoredetailbelow.©2004InsuranceInstituteforHighwaySafetyGuidelinesforRatingInjuryMeasures1005N.GlebeRoad,Arlington,VA22201.Allrightsreserved.May2004—1Table1InjuryParameterCutoffValuesAssociatedwithPossibleInjuryProtectionRatingsBodyRegionParameterIARVGood–AcceptableAcceptable–MarginalMarginal–PoorHeadandneckHIC-15700560700840Nij1.000.801.001.20Neckaxialtension(kN)3.32.63.34.0Neckcompression(kN)4.03.24.04.8ChestThoracicspineacceleration(3msclip,g)60607590Sternumdeflection(mm)–50–50–60–75Sternumdeflectionrate(m/s)–8.2–6.6–8.2–9.8Viscouscriterion(m/s)1.00.81.01.2Legandfoot,Femuraxialforce(kN)–9.1–7.3–9.1–10.9leftandrightTibia-femurdisplacement(mm)–15–12–15–18Tibiaindex(upper,lower)1.000.801.001.20Tibiaaxialforce(kN)–8.0–4.0–6.0–8.0Footacceleration(g)150150200260HeadandNeckHeadinjuryriskisevaluatedmainlyonthebasisofheadinjurycriterion(HIC)witha15mslimitontheperiodoverwhichitiscalculated.Avalueof700,whichisthemaximumallowedundertheprovisionsoftheU.S.advancedairbagregulation(NationalHighwayTrafficSafetyAdministration(NHTSA),2000),markstheborderbetweenanInstituteratingofacceptableandmarginal.AHIC-15of700isestimatedtorepresenta5percentriskofasevereinjury(Mertzetal.,1997).A“severe”injuryisonewithascoreof4+ontheAbbreviatedInjuryScale(AIS)(AssociationfortheAdvancementofAutomotiveMedicine,1990).InadditiontoHIC-15,themaximumvectorresultantaccelerationoftheheadisconsidered.Amaximumheadaccelerationthatexceeds70gandiscausedbycontactbetweentheheadandahardsurfaceofthevehicleinteriorcanresultinloweringtheheadinjuryratingonelevel.IfthemaximumheadaccelerationoccursduringthemaximumHIC-15interval,thenonlyanotherwisegoodhead/neckratingwouldbedowngraded,toacceptable.IfthemaximumheadaccelerationoccursoutsidethemaximumHIC-15interval,thenthehead/neckratingwouldbedowngradedonelevelregardlessoftheratingindicatedbyothermeasuresontheheadandneck.(However,iftwodistincteventscausedheadaccelerations70g,thehead/neckratingwouldbedowngradedonlyonelevel.)Thisadditionalcriterionforevaluatingprotectionoftheheadisbasedonconcernaboutmoderateandseriousinjuries(AIS2-3)tothefaceandweakerpartsoftheskullthanarerepresentedbythebiomechanicaldataunderlyingtheestablishmentofHIC.Thisisaparticularconcernwhenthehighaccelerationsarecausedbyheadimpactsagainsthardstructureswithrelativelysmallareasofcon