Human Tolerances to Injuries and

Road Safety & Safer Vehicle Design Techniques

Dr. Harald Zellmer06.12.2019

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1. Introduction

2. Injury Assessment

3. Road & Vehicle Safety

Human Tolerances and Safe Transport

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1. Introduction

2. Injury Assessment

3. Road & Vehicle Safety

Human Tolerances and Safe Transport

The Risk of Fatal Accident per Year

• By lightnings 1: 20 000 000 (Germany)

• By natural disasters 1: 150 000 (World)

• By road accidents 1: 50 000 (Sweden) *) 1: 25 000 (Germany) *) 1: 8 000 (USA) *) 1: 6 000 (India) *) 1: 3 000 (Germany 1970)

• For comparison: maximum credible accident **) of a nuclear power plant

1: 10 000 (World)

*) WHO 2015

500 nuclear power plants means 1 accident every 20 years Chernobyl 1986 Fukushima 2011

**) Beyond-design-basis event4

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Risk Perception

• By lightnings 1: 20 000 000 (Germany)

• By natural disasters 1: 150 000 (World)

• By road accidents 1: 50 000 (Sweden) 1: 25 000 (Germany) 1: 8 000 (USA) 1: 6 000 (India) 1: 3 000 (Germany 1970)

High or Low?

The Risk of Fatal Accident per Year

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How to Reduce the Risk?

• By lightnings 1: 20 000 000 (Germany)

• By natural disasters 1: 150 000 (World)

• By road accidents 1: 50 000 (Sweden) 1: 25 000 (Germany) 1: 8 000 (USA) 1: 6 000 (India)

The Risk of Fatal Accident per Year

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Vision Zero... was introduced in Sweden in 1997

... is a philosophy of road safety that eventually no one will be killed or seriously injured within the road transport system (C. Tingvall)

All stake holders of the road transport system, i.e. designers and road user are responsible that no accident occurs

In case that in spite of this an accident occurs, the resulting crash, e.g. the collision between a car and a pedestrian or the collision between two cars should not result in serious or fatal injuries

-> Make the crash a design-basis event

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The Natural Speed• What is the natural speed of humans?

Run

the world record for 100 m is about 10 s, i.e.

10 m/s or 36 km/h

Fall

head drop height 1.8 m

6 m/s or 22 km/h

Thus, impact speeds of about 30 km/h should be survivable without serious or severe injuries

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The Natural Speed

• The risk of injury is dependent on – Age – Gender – BMI – .... yes

no XX X X X X XX X

X XX X XX X XX X

Injury

Parameter e.g. Speed

Transition Region

No Injury Region

Injury Region

= Injury Risk Curve

Injury Risk Curve

• Different risk curves for – Age – Gender – BMI – .... 1

0

Injury Risk

Parameter e.g. Speed

0.5

Which injury risk is acceptable?

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?

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Why a Collision Occurs

• E.g. due to distraction

Then Now

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Why a Collision Occurs

• E.g. due to distraction

It doesn't matter whether the human or the car is at a speed of 30 km/h

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Possible Maximum Travel Speeds

C. Tingvall: Vision Zero

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Possible Maximum Travel Speeds

C. Tingvall: Vision Zero

?

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1. Introduction

2. Injury Assessment

3. Road & Vehicle Safety

Human Tolerances and Safe Transport

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Biomechanics definition:

Biomechanics is the study of the structure and function of biological systems such as humans, animals, plants, organs, and cells by means of the methods of mechanics.

Source: Wikipedia

Here we are talking about Injury Biomechanics

Injury Assessment - Biomechanics

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Target: The definition of

Injury Assement Reference Values (IARV)

for each part of the body

Injury Assessment - Biomechanics

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Injury Causing Loadings to the Body

Two persons are moving (too) fast and are distracted

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Spe

ed

Time

Acc

eler

atio

n

Gladstone

Donald

Injury Causing Loadings to the Body

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• Linear accelerations• Rotational accelerations• Forces• Moments• Duration of loading• Combination of two or more loadings

Injury Causing Loadings to the Body

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Target: The definition of an Injury Assement Reference Value (IARV) for each part of the body

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Definition of IARV

Proceeding:– Investigate accidents and find out which part of the body is

injured in which crash type– Develop a method to apply a loading to the human body like

in the real crash but in laboratory conditions– Perform a sufficiently large number of such tests– Define a method to relate measured data in the laboratory

tests to injury outcome – Define a boundary between acceptable and non acceptable

injury severity

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Definition of IARV

Proceeding:– Investigate accidents and find out which part of the body is

injured in which crash type– Develop a method to apply a loading to the human body like

in the real crash but in laboratory conditions– Perform a sufficiently large number of such tests– Define a method to relate measured data in the laboratory

tests to injury outcome – Define a boundary between acceptable and non acceptable

injury severity

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AIS = Abbreviated Injury Scale

Quelle: Appel, Krabbel; Unfallforschung, ...

Simple description according to Dinesh Mohan

AIS- Code

Injury Severity Description

1 Minor Injury can be treated without medical doctor e.g. hematoma

2 Moderate Injury needs treetment by a medical doctor, but no need for hospitalisation, e.g. fractured arm

3 Serious Treetment needs hospitalisation, no direct thread to life e.g. open fracture of tibula

4 Severe Treetment needs hospitalisation, thread to life, survival probable, e.g. loss of a leg above knee

5 Critical Treetment needs hospitalisation, thread to life, survival questionable, e.g. critical head or thorax injuries

6 Maximum AIS 6 rather indicates an injury outcome than a severity, e.g. decapitation

Easy to memorize and more than 80% correct

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Source: Appel, Krabbel; Unfallforschung, ...

AIS and risk of fatal injury outcome

AIS = Abbreviated Injury Scale

Risk of fatal outcome

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Fatalities in Road Traffic Accidents EU15

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Injuries in car accidents

Frontal Impact

Front seat (N=755)

% MAIS 1+

Front seat (N=755)

% MAIS 2+

Head 7,2 2,5Face 0,8 -Neck 2,4 0,9Arms 8,3 1,7

Thorax 10,9 3,8Abdomen 2,1 1,2

Spine 2,8 0,5Legs 7,0 2,8Sum 41,5 13,4

Source: Cuerden, Scott, Hassan & Mackay: "The Injury Experience of Adult Rear Seat Passengers", IRCOBI ´97

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Develop IARV for:

• Head• Thorax• Femur

• Neck

• Tibia & Foot

} Started in the 1940th

1980th

1990th

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Example: Thorax

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Source: Gaudin etJones, “Human Anatomy and Physiology“, HBJ, 1989

Source: Wikipedia

Example: Thorax Anatomy

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AIS 2+ thorax injuries in car accidents

Example: Thorax

Source: Kramer, F.: Passive Sicherheit von Kraftfahrzeugen 1998, [15] Cavanaugh, JM: The Biomechnaics of Thoracic Trauma. In: Accidental Injury – Biomechanics and Prevention. Editors: Nahum & Melvin, 1993.

Skeleton *)

Driver Passenger

Injured Body Part

Spine

Joints

Heart

*) Fractures of ribs, sternum and clavicle

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Definition of IARV

Proceeding:– Investigate accidents and find out which part of the body is

injured in which crash type– Develop a method to apply a loading to the human body like

in the real crash but in laboratory conditions– Perform a sufficiently large number of such tests– Define a method to relate measured data in the laboratory

tests to injury outcome – Define a boundary between acceptable and non acceptable

injury severity

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Test Subjects and Objects1. Volunteer tests

4. Accident reconstruction

2. Animal tests3. Tests with PMTS

5. FEM-Simulation

1

3

2

4

5

Source: Toyota

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Example: ThoraxTable Top Test

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Definition of IARV

Proceeding:– Investigate accidents and find out which part of the body is

injured in which crash type– Develop a method to apply a loading to the human body like

in the real crash but in laboratory conditions– Perform a sufficiently large number of such tests– Define a method to relate measured data in the laboratory

tests to injury outcome – Define a boundary between acceptable and non acceptable

injury severity

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cadaver test with a 73 years old male, each rib fitted with strain gages, load rate approx. as in crash

Example: Thorax Table Top Test

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Example: Thorax

20 mm 50 mm

Chest Compression for an average male

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Definition of IARV

Proceeding:– Investigate accidents and find out which part of the body is

injured in which crash type– Develop a method to apply a loading to the human body like

in the real crash but in laboratory conditions– Perform a sufficiently large number of such tests– Define a method to relate measured data in the laboratory

tests to injury outcome – Define a boundary between acceptable and non acceptable

injury severity

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Example: Thorax50th percentile male

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Definition of IARV

Proceeding:– Investigate accidents and find out which part of the body is

injured in which crash type– Develop a method to apply a loading to the human body like

in the real crash but in laboratory conditions– Perform a sufficiently large number of such tests– Define a method to relate measured data in the laboratory

tests to injury outcome – Define a boundary between acceptable and non acceptable

injury severity

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Problems in Defining IARVs• IARVs are only valid for the loading for which they were

developped• Strictly speeking: Table-Top-Tests are only valid for seat belt induced

injuries

• Only a limited number of tests are available

• Every human is different• Gender• Height• Weight• Age

• The definition of IARVs has also a political side: • Which part of the population is at interest? • What is the commonly accepted risk?

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Regulation USA old

Regulation USA new

Regulation Europe

Consumer Test Europe Euro NCAP

green limit ~ 1.8% injury risk

Example: Thorax50th percentile male

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Definition of IARV

Proceeding:– Investigate accidents and find out which part of the body is

injured in which crash type– Develop a method to apply a loading to the human body like

in the real crash but in laboratory conditions– Perform a sufficiently large number of such tests– Define a method to relate measured data in the laboratory

tests to injury outcome – Define a boundary between acceptable and non acceptable

injury severity

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At the End we now have IARV for

• Head

• Neck

• Thorax

• Femur

• Tibia & Foot and we have dummies to do tests

For frontal impacts, different IARV for side impact or rear impact

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1. Introduction

2. Injury Assessment

3. Road & Vehicle Safety

Human Tolerances and Safe Transport

46

A Systematic of Road Traffic Safety

Road Traffic Safety

Passive Safety Measures to reduce Accident Outcome

Active Safety Measures to avoid

Accidents

Vehicle Safety of the Vehicles

Human Safety of the Road Users

Environment Safety of the Traffic Routes

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A Systematic of Passive Vehicle Safety

Road Traffic Safety

Passive Safety Measures to reduce Accident Outcome

Active Safety Measures to avoid

Accidents

Vehicle Safety of the Vehicles

Human Safety of the Road Users

Environment Safety of the Traffic Routes

External Safety Structural Safety Internal Safety

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External Vehicle Safety

• No sharp Parts which could hurt Vulnerable Road Users • Deformability • Protective Clothing

Source: Zellmer et al. IRCOBI 1995

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Structural safetyStiff compartment

progressive crumble zone

Source: U. Seiffert, Fahrzeugsicherheit

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Internal Safety

Quelle:

Seat belt, airbag, seat, side impact protection, padding of instrument panel

Source: U. Seiffert, Fahrzeugsicherheit

What Happens in a Frontal Impact?

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Car and Occupant

Behaviour in

Frontal Impact

Source: Zellmer et al. 1999

Occupant Kinematics in a Frontal Crash

Time in milliseconds

driver

passenger

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Source: U. Seiffert, Fahrzeugsicherheit

Occupant Kinematics in a Frontal Crash

Test speed is 40 km/h54

t = 0 ms

t = 130 mst = 70 ms

t = 40 ms

Source: Dekra, Winterthur, Autoliv

Harald Zellmer: Occupant Safety and Restraint Systems

Crash Tests in Regulations and Consumer Ratings

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Are to represent the following crash scenarios:

Frontal impact vehicle to barrier at up to 56 km/h

Frontal impact vehicle to vehicle at up to 56 km/h

Vehicle to vehicle side impact at up to 50 km/h

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Possible Maximum Travel Speeds

C. Tingvall: Vision Zero

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End