presentation EVU Netherland 31102013 · Comotio cerebri (AIS 2) Dislocated lower leg fracture left...

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GIDAS German In-Depth Accident Study

Hannover Medical SchoolMedizinische Hochschule Hannover

The Accident Research Unit

Content of lecture• Vulnerable road users are the main topic• Research on In-Depth-Investigation i.e.

GIDAS • New Aspects on Bicycle Helmets• Whiplash problematic• Practices on forensic expertises in Germany

Accident Research and ForensicsTasks common

• Accident analysis• Accident causation• Aviodance stategies• Injuries and injury pattern• Speed of driving• Impact Speed• Avoidance speed•

workprocess• Documentation of traces• Questionairing witnesses and

participants• Analysis of injury causation and

mechanisms• Determination of impact and

driving speed• Avoidance and failures• Effectiveness of safety eqippments• Impact and moving behavior of

persons

Real World Analysis Experimental Simulation

Nat. + int. statisticsAccident Research Unit

CrashtestsComponent tests

Vehicle developmentField analysesComputersimulation

In-Depth Research Teams Germany

Dresden

Hannover

since1999

InvestigationArea60 km radius

since1973

Technical University Dresden

2000accidents

annual

1000 accident 1000 accident

Medical University Hannover

By order of Federal Highway Research Institute BASTAutomotive Research Association FAT

methodology

MAIS 2AIS-Head 2

AIS-Arms 2

AIS-Legs 2

Commotio Cerebri AIS 2

Laceration Head right frontal AIS 1

Fracture of head of radius right AIS 2

Rupture left crucial ligament AIS 2

Kind + Location + Severity AIS 2005

Injury documentation

Abbreviated Injury Scale

3020100207

3-D-picture scene of accident (30060206)

3-D-Scan

- 10 -

True to scale drawing as basis for reconstruction

- 11 -11/18/2013 11

On scene investigation Hannover

Number of cases 1973 to 2013Accidents 29.359Vehicles 56.143Persons 73.486Casualties 39.532Injuries 131.501

01.0002.000

Year of investigation

- 12 -

Pedestrian Safety

- 13 -

car frontal against pedestrian – in the 70s

MAIS 3Collision Opel Ascona frontal against pedestrian,Collision speed 45 kph,Deformation front edge of hood,Impact on windshield

Pedestrian female, 48 years, MAIS 3Contusions and abrasions (AIS 1)Comotio cerebri (AIS 2)Dislocated lower leg fracture left (AIS 3)Symphyseal disruption (AIS 2)

Development of safety

- 14 -

vehicle part is cause of injury

57.3%32.1%

21.3%26.2%

road surface 59.9%

53.3%53.1%

frequencies of injured body regions

injured by body impact with

total n = 392

pedestrian - collision with car - 70-ies

- 15 -

car frontal against pedestrian – in the 90s

MAIS 2Collision VW Jetta frontal against pedestrian,Collision speed 45 kph,Impact on right front bumper and hood

Pedestrian female, 21years, MAIS 2Abrasion forehead right side (AIS 1)Abrasion right hand (AIS 1)Abrasion right knee (AIS 1)Fracture of left fibula (AIS 2)

1991-217

- 16 -

42.5%23.2%

8.8%16.3%

road surface 58.7%

33.0%31.8%

total n = 1074

pedestrian - collision with car - 90-ies

- 17 -

car frontal against pedestrian – up to date

MAIS 1Collision BMW-one frontal against pedestrian,Collision speed 45 kph,Deformation front edge of hood,Impact on windshield

Pedestrian male, 56 years, MAIS 1Contusions and abrasions (AIS 1)

30120539

- 18 -

37.6%22.0%

6.3%17.7%

road surface 52.7%

27.1%26.5%

total n = 780

pedestrian - collision with car - actual

- 19 -

Injury probability pedestrians (adults > 150 cm)Collisions of car-front

total n = 935

bis 30 31-50 51-70 > 70

Collision speed car

MAIS 1Slightly injured

MAIS 2-4Seriously injured

MAIS 5/6Most heavily injured

killed

- 20 -

Impact of pedestrians < 40 km/hFrontal impact – all types of cars

Maximum x-distanceHead-impact

- 21 -

Head-impact Maximum x-distance

Impact of pedestrians > 40 km/hFrontal impact – all types of cars

- 22 -

Testvorschlag für die Windschutzscheibeaccident reality

- 23 -

BICYCLISTSHistory of Traffic Safety

- 24 -

15.2%15.2%

road surface 60.4%

total n = 217

bicycle collision with car - 70-ies

- 25 -

5.8%11.8%

road surface 70.8%

total n = 1614

bicycle collision with car - 90-ies

- 26 -

• especially effectivefor persons > 40 yeard

elderly persons

good protections against head injuries by bicycle helmets

bicycle helmet increases safety

helmet

without

age classification

- 27 -

European Standard for bicycle helmet production

SichtfeldHorizontal min. 105 GradNach oben min. 25 GradNach unten mind. 45 Grad

StoßdämpfungStirn, Hinterkopf,Seiten, Schläfen, Oberkopf schützenMax.Beschleunigung < 250g 5,42 m/s flacher Sockel (1,5m)4,57 m/s Bordsteinkante (1,0m)

Trageeinrichtung Dyn. Dehnung max. 25 mm

- 28 -

Shock Absorber Test of Helmet

test area above by „Worst case Method“

determination of test area

1 reference level2 reference line for angular measurement

- 29 -

Bilder der Radhelme

30040547 30050479 30050711

30050800 30060275 30060712

experiences from real world accidents

- 30 -

Definition of Impact and Damage Matrix on Helmet

protective areby CEN 1078

- 31 -

Scratches, Traces

Bursts

Deformations

Location of Damages / Impact Areas on Helmet

- 32 -

Proposal for Extension of Protective Area

- 33 -

Radhelm und Verletzungsschwere Radfahrer

2,8 0,7 0,0 0,04,3

2,8 0,7 0,3 0,00

1020304050607080

notinjured

MAIS 1 MAIS 2 MAIS 3 MAIS 4 MAIS 5 MAIS 6

maximum injury severity grade

with helmet (n=433) without helmet (n=3812)

- 34 -

Injury Severity Grade of Head

18,111,1

0,2 0,4 0,0 0,0

8,80,9 0,5 0,2 0,0

01020304050607080

notinjured

AIS 1 AIS 2 AIS 3 AIS 4 AIS 5 AIS 6

injury severity grade of head

with helmet (n=433) without helmet (n=3812)

AIS > 2 1.6 % without helmet0.6 % with helmet

- 35 -

Frequencies of Head Injuries

0,2 0,2 2,6

1,2 0,5 2,7

10152025303540

skullfracture

braininjury AIS

basefracture

facialfrakture

softtissueinjury

head injury

with helmet (n=433) without helmet (n=3812)reduction 75%

reduction 83%

reduction 60%

reduction 33%

- 36 -

Example: Bicyclist without Helmet

impact zone left sideheadimpact windscreen

- 37 -

Example: Bicyclist without Helmetbicyclist:

female, 69 JahreMAIS 3

compression fracture skulldeeply wound fronthead

fracture right patellacompl. fracture right lower legmultiple soft tissue injuries legs

- 38 -

Example: Bicyclist with Helmet

impact zone front wheel

head impact A-pillar

- 39 -

bicyclist:

male, 8 Jahre

MAIS 1laceration left knee

no injuries head

- 40 -

used helmet deformation outer shell by impact with A-pillar

- 41 -

Statistical Probability to Suffer Head Injuries - ODDS-RATIO

• Odd Ratio, to rate the difference of two Odds resulting in classifying the intensity

• values >1 increasing probability• values <1 decreasing probability

Task variable AIS-HeadBrain Injury AIS >3Facial Fracture

- 42 -

Logistical Regression AIS-Head Odds Ratio p

impact speed collision partner 1.035 <0,0001age of bicyclist 1.011 <0,0001BMI 1.000 0.9856accident location rural 2.131 <0,0001daytime dust

night1.1321.298

0.95800.0950

type of bicycle BMXbicycle n.f.s.mountainbikeracing bicycle

1.6491.0041.1151.049

0.21060.17110.80660.5529

cycle path none, not used 1.463 <0,0001collision partner object 1.469 <0,0001

bicyclepedestriantruckmultiplemot. two-wheeler

0.9020.7501.5771.1330.908

0.05890.03390.00690.99520.3799

gender female 1.066 0.9587helmet without 1.503 0.0005

- 43 -

Logistical Regression Brain Injuries AIS 3+(n=62 vs. 1153)

Odds Ratio pimpact speed collision partner 1.070 <0.0001age of bicyclist 1.025 0.0023BMI 1.046 0.1403accident location rural 0.779 0.6179daytime dust

night1.3452.178

0.09780.1219

0.0010.9251.7961.271

0.92200.93660.90000.9191

cycle path none, not used 1.463 0.1831collision partner object 2.652 0.6889

1.7970.0011.0612.9810.001

0.73060.87340.78770.67770.8061

< number of cases!

- 44 -

Logistical Regression Facial Frakture (n=124 vs. 4091)

Odds Ratio pimpact speed collision partner 1.026 <0.0001age of bicyclist 1.005 0.3302BMI 1.031 0.1922accident location rural 2.060 0.0276

daytime dustnight

0.8351.672

0.28360.0541

2.8910.9920.8661.116

0.16780.35740.14630.7939

cycle path none, not used 1.378 0.0935collision partner object 4.582 <0.0001

2.4730.5202.1381.9050.656

0.13150.23600.29530.70440.3647

not significantinfluence in question

- 45 -

Conclusion !

• 40% of bicyclists without helmet (30 % with helmet) suffer headinjuries

• 70% ……………………………….at impact speed v >40 kph• 5.4% of bicyclists with head injuries are AIS>2 (0.9% with

helmet) • byciclists with helmet are more young people, seniors are rare• byciclists with helmet more often use street 57% vs. 42%

without helmet• racing biker more often use helmet and are driving on the street• usage is low rural, by night, age of bicyclist >50 years

Protective Effect of Helmet is Clearly!

- 46 -

Effectiveness of Bicycle HelmetVerifiable by Accident Studies

• protection from soft tissue injuriessoft tissue injuries – 35 %

• especially from severe injuriesskull fractures – 71 %brain injuries – 82 %base of skull fractures – 58 %

- 47 -

Analysis of accidentcause in on sceneinvestigations

ACAS Accident Causation Analysis System

- 48 -

On scene investigation• Show inside in accident occurence• Show injury pattern and detailed injuries• Explain injury mechanism• Find accident causes and human behavior• Probability of occurence of injuries• Influence parameter of injuries

- 49 -

• Interdisciplinary survey

technical

medical

traffic psychology

HOW CAN KNOW-HOW BE USED?

- 50 -

How can know-how be used?

• Interdisciplinary expertises

ForensicTechniqueBiomechanics

Medicine

& other disciplins

- 51 -

How can know-how be used?• Interdisciplinary expertises

- 52 -

How can know-how be used?

• Interdisciplinary expertises• Sitting position in the car• Usage of seatbelt• Efficiency of helmet usage• Injury mechanism• Injury causation• Walking direction• Suicidal intent• Injuries accident probability

• Correlation of damages• Speed calculation• Avoidance strategies• Possibility of sight• Possibility of visibility• Hit or run• Insurance fraud• Roll over of human body

- 53 -

Whiplash

- 54 -

Difficulty of Whiplash diagnosis•Practical case – forensical surveys – rear-end collision•Situation of cars and accident severity

•Diagnosis: based on accident event•

Delta-v 4,5 kph up to 6 kphh 1,5 g up to 2,5 g

- 55 -

Basis of assessment: accident severity

Delta-v 4,5 kph up to 6 kph 1,5 g up to 2,5 g

- 56 -

•Academic basis is comprehensive but not completely enlightening yet!

Probability of occurence

Frontal-collision (flexion of cervical spine) Vehicle deceleration > 5 – 8 g (v > 10 kph)

Rear-end collision (hyperextension of cervical spine):Vehicle deceleration > 2 g (v > 3 kph)

Lateral collision (lateral flexion of cervical spine):Vehicle deceleration > 6 g (v > 3 kph)

No absolute values usable!At best guidance according to scientific literature

- 57 -

How in-depth-accident surveys are shown WhiplashCar occupant with seatbelt in GIDAS

10,2 9,7

8,8 10,7

Front Side Rear-end multipleImpact car

year of construction < 2005 (n=24.223)year of construction greater equal 2005 (n=3.071)

Frequency % of whiplash injuries

- 58 -

Data basis: rear-end collisionsaccidents 1999-2012

n=26.104

accidents reconstr.n=23.391

participantsn=45.070

n=2.763Occupants

front seated

STATUSnot completed n= 2.255without reconstruction n= 458

participantstruck n= 2.736bus, tram n= 897Motorized two-wheeler n= 3.540bicycle n= 7.058pedestrian n= 3.145other n= 108unknown n= 2

excluded

carsn=27.584

delta-v unknown n= 4.239multiple collisions n= 2.478Collision partner no car n= 9.440No rear-end collision n= 9.002coll. partner not frontal n= 80mass car unkown n= 114mass coll. partner unkn. n= 61cars n=2.170

occupants frontn=2.952

Injury severityMAIS unknown n= 66age unknown n= 123

- 59 -

geRegression coefficient B

Standard error

Wald df Sig. Exp(B) 95% confidence intervalfor EXP(B)

Lower value Superior value

Step 1a

DELTAV ,015 ,002 58,960 1 ,000 1,015 1,011 1,019Age -,010 ,001 45,103 1 ,000 ,990 ,988 ,993

Kind of impact 871,262 2 ,000

Kind of impact (1) 1,758 ,060 858,333 1 ,000 5,801 5,158 6,525Kind of impact (2) ,253 ,065 15,393 1 ,000 1,288 1,135 1,462Sex (1) ,905 ,047 370,657 1 ,000 2,473 2,255 2,712

Mass coll. partner 23,769 2 ,000

Mass coll. partner (1) ,195 ,066 8,727 1 ,003 1,215 1,068 1,383

Mass coll. partner (2) ,310 ,064 23,666 1 ,000 1,363 1,203 1,544

Mass car 3,365 2 ,186

Mass car (1) ,104 ,057 3,341 1 ,068 1,109 ,993 1,240

Mass car (2) ,081 ,074 1,190 1 ,275 1,085 ,937 1,255

Direction of impact (1) ,295 ,053 30,783 1 ,000 1,344 1,210 1,491

Constant -2,435 ,102 567,022 1 ,000 ,088a. In step 1 entered variables: DELTAV, age, kind of impact, sex, mass collision partner, mass car, direction of impact.

- 60 -

Except for the mass of the carall parameter show a highly significantinfluence.

This means,that delta-v solely shows influencebut not alone !

it can be seena significant influence in interaction withother variables

- 61 -

Amount of isolated whiplash injuries in rear-end collisions

01020304050607080

1 2 3 4 5 6 7 8 9 10111213141516171819202122232425262728

Delta-v [kph]

whiplash MAIS 1 MAIS 2+Poly. (whiplash) Poly. (MAIS 1) Poly. (MAIS 2+)

- 62 -

0102030405060708090

1 3 5 7 9 11 13 15 17 19 21 23 25 27 29 31 33 35 37 39

Delta-v [kph]

whiplash MAIS 1 MAIS 2+

Poly. (whiplash) Poly. (MAIS 1) Poly. (MAIS 2+)

Amount of isolated whiplash injuries in lateral collisions

- 63 -

01020304050607080

1 3 5 7 9 1113151719212325272931333537394143454749

Delta-v [kph]

whiplash MAIS 1 MAIS 2+Poly. (whiplash) Poly. (MAIS 1) Poly. (MAIS 2+)

Amount of isolated whiplash injuries in frontal collisions

- 64 -

Whiplash injuries conclusion

• symptoms of whiplash injuries possible atall accident constellations and Delta-v values

• Duration and scope of complaints areindependent from Delta-v values andmedical finding of steep position of cervicalspine

- 65 -

Duration and scope of complaintscorrelate with physiologic parameters

gendervigour / traininghealth situation

degenerative pre-existing defects

- 66 -

81,477,3

72,581,4

64,460,4

50,4 50,8

0102030405060708090

whiplash injury chronic pain german standard population

SF 36: whiplash injuries

Correlates with chronic pains

- 67 -

pre-existing affection orinjury of spine?

• What is accidental cause?

• malposition, stiff segments?

• Does the pain correlate with:• malposition,instability?

• Degeneration and influence?

- 68 -

Surveys: Diagnostic approach• anamnesis: afflictions• statics / functional examination• nerve examination• x-ray, CT, MRT• progression

- 69 -

How a Whiplash case can be handled?

• Can only be answered in interdisciplinary surveys!

Investigation of accident collision sequences

Investigation of occupant kinematics and biomechanical stress

Assessment of injuries and symptomatologyInclusion of additional experts (neurosurgery, psychological, …)

if necessary

Interdisciplinary report

- 70 -

Examples

- 71 -

Elderly lady declares, thatshe tumbled over thedefect banister after leaving her apartment.

She was found lying in front of the door one floordownstairs

Causation of plunge in staircase

- 72 -

Metodology of expertises:

Preparing a true to scaledrawing

Reconstruction ofaccident with motionanalysis andassessment of injuries

Causation of plunge in staircase

- 73 -

Plunge in staircase – profile of staircase from point cloud

Final position ofcomplainant

Top floor – apartmentof complainant

banister, over which shetumbled (according toher own statement)

- 74 -

Plunge in staircase - Simulation with PC-CrashDifferent motion sequences can be simulated this way:Plunge from stairs (final position reached)

- 75 -

Plunge in staircase - „Walk“ over stairs

Different motion sequences can be simulated this way:Plunge over banister (final position not reached)

Conclusion

Only possibleFalling on stairsLower stairs levelNo influnce from fender

- 76 -

Example

- 77 -

Visibility of a person in a run overAccident:In the morning hours (darkness) a person lying on the roadsurface was run over by a car in a right-hand bend.Question: preventability of the accident by the car driver?

Photos from the official photo report

- 78 -

Run over a person

True to scale sketch :Final position of the person (claimant) and location of thecollision approx. 3 m in front of the final position

- 79 -

Run over a person

Quelle Otte Dipl.arb. 1975

Approach: From experimental run overs: collision positionapprox. 3 to 4 m in front of the final position of the person

- 80 -

Run over a personApproach:• investigation of possible influence of the light towers with known light beam• include light beam of car in the simulation• Road trials on accident scene with dummy (darkness)

- 81 -

Run over a person

Die Sicht auf den Dummy mit

Abblendlicht:

- 82 -

Example

- 83 -

Injury of a person in an isolated braking maneuver?Event:

A car driver indicates, that he was forced to an emergencybraking maneuver

Approach: Investigation of occurred force with seatbelt

1. approximation: balloon between person and seat belt

2. approximation: measure the load with a pressure indicatingfilm

Sternum fracture with or without seatbelted ?

- 84 -

Injury of a person in an isolated braking maneuver?1. approximation: balloon between person and seat belt for

illustration of the occuring forces

- 85 -

Injury of a person in an isolated braking maneuver?2. approximation: measure the pressure / forces with a pressure indicating film for driver and passenger

- 86 -

Only very low pressures present.

max. pressure 0,0005 MPa to 0,0013 MPa equal to 500 Pa to 1300 Pa or 5,0 g/cm² to 13,0 g/cm².max. force between 0,3 N and 1,9 N in static viewapprox. 30 gram to 190 gram

Injury of a person in an isolated braking maneuver?

2. approximation: measure the pressure / forces with a pressureindicating film

- 87 -

Other Parameter useful for reconstrution

• Throw distance of peds, bics• Injury severity parameter for safety

devices (helmet, seatbelt..)• Injury probability functions

AIS = f(speed, delta-v, EES, rel. Speed)

- 88 -

throw distances of pedestrians

0 20 40 60 80 100

impact speed car [kph]

- 89 -

impact speed vs. injury severity of bicyclists

0 20 40 60 80 100 120

no impact windscreen area windscreen impact A-pillar impact

- 90 -

throw distances of bicyclists

101214161820

0 10 20 30 40 50 60

central car edge

- 91 -

Fahrradfahrery=(.164285)*x+(.396E-3)*x*x

0 20 40 60 80 100

impact speed

bicyclists

- 92 -

Fussgängery=(-.01499)*x+(.006025)*x*x

0 10 20 30 40 50 60 70 80 90

impact speed

pedestrians

- 93 -

functional variable: throw distance[m]source square sum

of type IIIdf mean of

squaresF Sig.

corrected modell 2954,596a 9 328,288 42,295 ,000constant term 10,010 1 10,010 1,290 ,257Walking direction 126,392 3 42,131 5,428 ,001type of car ,000 0 . . .front collision 30,661 2 15,330 1,975 ,140car braking ,950 1 ,950 ,122 ,727impact speed 2530,227 1 2530,227 325,980 ,000body height cm ,060 1 ,060 ,008 ,930first registration 9,486 1 9,486 1,222 ,270failure 2701,146 348 7,762

total 11314,115 358corrected total variation 5655,742 357a. R-square = ,522 (corrected R-square = ,510)

overall linear modell (Varianz analysis)

- 94 -

Technical Parameters for Determination of Impact Speed for Motorcycle Accidents and the Importance of Relative Speed on Injury SeveritySAE Paper 06B-422 2006

Injury correlation of Relative speed

Throw distance

- 95 -

Conclusion

• Experiences of experts are needed• Data of accident research is needed• Interdisciplinary cooperation of experts

has benefits• Adoption of an interdisciplinary apporach

of biomechanics is important• Education sills of experts would be useful

- 96 -

Thank you very muchfor your attention !

presentation EVU Netherland 31102013 · Comotio cerebri (AIS 2) Dislocated lower leg fracture left...

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