Table Of ContentPedestrian and Cyclist Impact
SOLID MECHANICS AND ITSAPPLICATIONS
Volume166
SeriesEditor: G.M.L.GLADWELL
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Ciaran Simms Denis Wood
Pedestrian and Cyclist Impact
A Biomechanical Perspective
CiaranSimms DenisWood
CentreforBioengineering DenisWoodAssociates
TrinityCollegeDublin ConsultingForensicEngineers
Dublin Dublin
Ireland Ireland
ISBN 978-90-481-2742-9 e-ISBN 978-90-481-2743-6
Springer Dordrecht Heidelberg London New York
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To Lynn
Table of Contents
Foreword xi
Acknowledgements xiii
AbouttheAuthors xv
Chapter1:Introduction 1
Chapter2:PedestrianandCyclistInjuries 5
Introduction 5
GlobalViewofPedestrianandCyclistFatalityandInjuryRates 5
MainPedestrianandCyclistInjuryDatabaseSources 7
DistributionofPedestrianInjuries 8
DistributionofCyclistInjuries 10
InjuryRiskasaFunctionofAgeandSex 16
TheDistributionofVehicleImpactSpeeds 17
InjuriesfromVehicleandfromGroundContact 21
InjuryRiskasaFunctionofVehicleSizeandType 21
InjuriesandDisabilities 24
PedestrianInjuryTrendsoverTime 25
ConcludingRemarks 25
Chapter3:PedestrianandCyclistImpactKinematics 31
Introduction 31
SourcesforStudyingPedestrianandCyclistMovement 32
ClassificationofPedestrianandCyclistImpactConfigurations 32
PedestrianSideswipeCollisions 34
WrapProjection 35
Pedestrian/CyclistHeadContactinWrapProjections 40
ForwardProjection 43
PostHeadImpactKinematicsforForwardandWrapProjectionCases 45
ConcludingRemarks 48
vii
viii TableofContents
Chapter4:TheRelationshipbetweenVehicleImpactSpeedand
PedestrianandCyclistProjectionDistance 51
Introduction 51
StagesofPedestrianandCyclistProjection 52
PostImpactSeparationfromtheVehicle 53
EffectiveCoefficientofRetardationintheGroundContact 54
AccidentData 54
StagedTests 57
ComparisonbetweenAccidentReconstructionsandStagedTests 58
RegressionModelsRelatingImpactSpeedtoPedestrianProjection
Distance 60
PhysicsBasedModelsRelatingImpactSpeedtoPedestrian
ProjectionDistance 62
TheoreticalConsiderations:TheParticleProjectionModel 63
WrapProjection 66
PedestrianForwardProjection 67
ConfidenceLimitsforVehicleImpactSpeedPrediction 70
OtherModels 70
ConcludingRemarks 72
Chapter5:InjuryMechanismsandInjuryCriteria 75
Introduction 75
HeadInjuries 76
HeadInjuryCriteria 77
SpinalInjuries 82
ThoraxInjuries 84
AbdominalInjuries 85
PelvisInjuries 87
LowerExtremityInjuries 87
TheLongBones:Femur,TibiaandFibula 88
TheKnee 92
TheAnkleandUpperExtremities 93
ConcludingRemarks 93
Chapter6:VehicleDesignStandardsforPedestrianandCyclistSafety 99
Introduction 99
BodiesDevelopingPedestrianSafetyStandards 100
TypesofTestProposed 101
SubsystemTests:LegformImpactortoBumper 102
UpperLegformtoBonnetLeadingEdge 104
HeadformtoBonnetTop:AdultandChild 107
ImplementationintoLegislation 109
ConcludingRemarks 111
PedestrianandCyclistImpactMechanics ix
Chapter7:MathematicalFormulationsforImpactModelling 115
Introduction 115
Notation 116
Timing 117
ImpulseandMomentum 118
SingleSegmentFormulationUsingMomentumConsiderations 120
PostPrimaryImpactKinematics 121
HeadContactTime 121
PostHeadImpactKinematics 122
PedestrianFormulationUsinganOrdinaryDifferentialEquation
(ODE)Approach 124
RigidBodyODEApproachwithaHingeSegment 127
Three-DimensionalEffects 130
ProblemswithaRigidBodyApproach 131
AFiniteElementApproachtoPedestrianImpact 132
ConcludingRemarks 135
Chapter8:ModelsforSimulatingImpact 137
Introduction 137
PedestrianPhysicalDummyModels 137
MathematicalModels 138
MultibodyModels 141
FiniteElementModels 145
ApplicationofFiniteElementPedestrianandCyclistModels 152
ConcludingRemarks 152
Chapter9:GroundContactInjuries 159
Introduction 159
RelativeSeverityofGroundVersusVehicleImpact 161
VariabilityofGroundContact 162
VehicleImpactSpeedEffects 163
InfluenceofVehicleDesign 165
PossibleMethodstoReduceGroundContactInjuries 168
ConcludingRemarks 169
Chapter10:TheInfluenceofVehicleDesignonPedestrianand
CyclistInjuries 171
Introduction 171
Definitions 172
InfluenceofVehicleMass 175
InfluenceofVehicleStiffness 176
InfluenceofOverallVehicleShape 178
BumperShape 181
InfluenceofBumperHeightonWhole-BodyKinematics 184
SecondaryBumper 185
x TableofContents
BumperLead 187
BumperStiffness 187
Bullbars 189
ShapeofBonnetandBonnetLeadingEdge 189
BonnetLeadingEdgeStiffness 194
HeadImpactontheBonnet/Windscreen 196
EvaluationofProductionVehiclesviaProposedPedestrian
SafetyRegulations 200
ConcludingRemarks 203
Chapter11:ConclusionsandFuturePerspectives 209
Introduction 209
EpidemiologyandIn-DepthCrashInjuryStudies 209
Kinematics 211
PopulationVariationstoInjuryandDisabilityOutcomes 212
ModellingandSimulation 213
CostBenefitCalculationsofFutureGainsforPedestriansandCyclists 214
ImmediateProblemsofPedestriansandCyclistsinLowIncomeCountries 214
SeperationofFastFlowingTrafficfromPedestriansandCyclists 215
ReductionofVehicleImpactSpeedwithPedestriansandCyclists 215
ImplementationofPedestrianFriendlyFront-EndDesigninThose
VehiclesWhichAreMostLikelytoCollidewithPedestriansandCyclists 216
DesignRequirementsforFutureVehicles 216
RequirementsforaGlobalPedestrian/CyclistFriendlyStandard 217
Conclusion 218
Index 221
Foreword
Inthe worldtodaythereareroughly800millioncars,trucksandbuses. Thereare
alsoperhaps500millionmotorcyclesandothermotorisedtwo-wheeledvehicles.No
onereallyknowshowmanybicyclestherearebut,since1990theannualproduction
ofbicycleshasbeenaround100million,soitislikelythattherearemorebicyclesin
theworldthanallotherroadvehiclesputtogether.Currentlyofroadtrafficdeaths
globally, three quarters of those deaths are to vulnerable road users, mainly ped-
estrians and cyclists. More importanthowever are the seriously injured survivors.
Althoughdataarefragmentaryinmanypartsoftheworld,foreverydeaththereare
atleastthreecasualtieswithserious,disablinginjuries;brainorneurologicaldam-
age or disruptionof a major jointin the lower limbs. Financially and socially,the
costsofthesurvivorsrepresentsome80%ofthecostsoftrafficinjuriestosociety.
Hence the importance of this book. Ciaran Simms and Denis Wood have pro-
ducedabookwhichisrelevanttopublichealthpolicymakers,transportationplan-
ners and particularly vehicle designers and the legislators who influence vehicle
exteriordesign.Bygivingabiomechanicalperspectivetothesubjectofpedestrian
andbicyclistimpacts,theyemphasizethe crucialimportanceofexteriordesign of
allroadvehicles.Historically,vehiclecrashworthinesshasbeenskewedbyactivit-
iesintheUnitedStateswherevehicleoccupantshavebeenthesoleconcernbecause
ofthehighlymotorised,carbasedconditionsinNorthAmerica.Moderncardesign
nowprovidestheoccupantswithairbags,seatbeltsanddeformingstructureswhich
minimisethecrashforcesbyprovidinglargeride-downdistancesinsevereimpacts.
It seems only right that the much more numerous pedestrians and cyclists in the
worldshouldgetafewcentimetresofusefulride-downdistanceandtheappropriate
exteriorshapetoreducetheseverityoftheinjurieswhichtheyreceive.
The authorsprovidean excellenthistoricalperspectiveof the topic, illustrating
itscomplexityandimperfectlydocumentedepidemiology.Theythenexplaininde-
tail the current tools which are available through experimental testing, improved
informationon impactinjury mechanics, injurycriteria and modelling.This leads
to the conclusionthatalthoughourknowledgeisstill imperfectwhatwe doknow
canandshouldbeapplied.Thebenefitsofsuchanapproachonaglobalscalecould
beenormous.
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