1. INTRODUCTION
Successful traffic injury prevention requires
multidisciplinary interaction and collaboration.
The subject is complex and various sectors
need to collaborate in order to achieve the
goal of eliminating or reducing the traffic
related unintentional injuries and fatalities. The
infrastructure development, safer vehicle designs,
educating road users and enforcing the law are the most
important facets of traffic injury prevention strategy after data
collection and data analysis phase.
As per the report from WHO (World Health Organization) the
road traffic injuries will be ranked third after heart disease
and depression by 2020. Traffic injury jumped from position
nine in 1990 to the projected third position in 2020 [World
report on road traffic injury prevention]. This clearly indicates
the rising nature of traffic related injuries and fatalities around
the world. India is among the leading countries for traffic
related deaths annually and cost multi billion dollars per year
[Bloomberg Report].
The 2013 NCRB Government of India
report shows 443001 reported road
accident cases with 469882 people
injured. This same data shows total
137423 people died in road accidents in
2013. Social losses on account of these
crashes are estimated at over Rupees
100 000 Crores annually or 3% of our GDP. The irony is that
these causalities are rising at 5.5% annually. India accounts
for 10% of the global road crash fatalities. Therefore, traffic
safety issue is very important in India.
The challenge India face is its big size with huge population
with diverse culture and languages which
mandates educational intervention to be in
different languages unlike western countries
with common language intervention schemes.
The road users range from motor vehicles to
animal powered carts which is a challenge for
law enforcement unlike western countries with
uniform motor vehicles type on roads.
Accident data analysis provides important information
regarding the types of accident, time of accident, location of
accidents and type of vehicle involved. This data collected
throughout India also provides the comparative analysis
between different cities and states. The Government NCRB
report provides valuable information that facilitates the
understanding of type and urgency of intervention schemes
required in various parts of country. For example, state of
Maharashtra leads the accidental death rates in country clearly
setting the priority of the implementation of interventions
schemes in this state and others following the list. This same
data in NCRB report reveals highest road accident deaths
of two wheeler riders followed by
the truck/lorry driver cabin occupants
demonstrating the vulnerability of two
wheelers on city roads and requirement
of special regulations and improved
infrastructure more focused on two
wheeler riders.
At present in India there is no government initiative or
research focused on injury causation analysis which requires
the engineering and medical input to understand the injury
mechanism. This approach is paramount to improve the
injury prevention strategies to reduce disabilities and deaths
on Indian roads affecting the productivity of India. The injury
Technical
Reference
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The strong side structure resisting the
intrusion and airbag system to dissipate
energy is the best countermeasure for
the side impact protection.
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causation analysis is extremely important for the Indian
Automobile Manufactures in order to contemplate and improve
the safety designs more focused for the Indian road scenarios.
Official statistics regarding accidents in India are available
in national and state wise reports. More detailed information
about accident causes, accident conditions and consequences
are roughly obtained. There is a lack of engineering data in
the available reports. To address traffic safety related issues
like infrastructure, driving behaviour and benefit of vehicle
safety systems, more detailed accident data is needed.
India is the second largest country in the world in traffic
accidents death (WHO Report). This indicates the extent of
awareness and improvement in Vehicle and Infrastructure to
reduce accidents.
The focus of this technical analysis is to briefly introduce
the importance and outcome of injury causation analysis by
reporting a real world accident investigation. Few proposed
solutions are provided in Indian context for reducing the
traffic accidents.
SYSTEMATIC INJURY PREVENTION
William Haddon some four decades ago in the United Sates
defined a very systematic way of understanding the phase and
factors influencing the injury prevention goal.
are very important for his behavioural change along with the
stringent regulation and law enforcement mandating the seat
belt use while driving. In other situation, a properly belted
elderly occupant is likely to sustain serious thorax injury
in absence of more advance seat belt feature such as the
load-limiter. This is a seat belt design issue for which the
respective manufacturer is responsible for implementing such
intervention to prevent serious to critical thorax injuries. This
example shows how a successful injury prevention strategy
mandates the contribution from every factor as discussed in
Haddon’s matrix during the impact phase. The prevention of
the accident is the best intervention scheme which requires
more systematic approach in developing the infrastructure.
INJURY CAUSATION ANALYSIS
The biomechanical analysis includes the occupant kinematics
and dynamics as dictated by the vehicle dynamics during
the crash scenario. Factors such as pre-impact occupant body
configuration, use of available safety features and occupant
conditions dictates the injury outcomes. The study of force and
moments acting on the human body in relation to the human
body tolerance is an important aspect of injury causation
analysis. The human tolerance is a function of various factors
such as age, sex, race, pre-impact body configuration and
tissue loading rate. The occupant kinematics analysis is an
important step in understanding the injury producing occupant
motion inside the vehicle which depends on the vehicle crash
dynamics. The exterior vehicle damage inspection provides a
good opportunity to understand the vehicle dynamics during
the crash phase in association with standard tests conducted by
the government. The presence of occupant vehicle interaction
marks inside the vehicle provides important insight regarding
their body motion envelope for the injury causation analysis.
The clinical findings from the medical records provide
important information regarding the sustained injury and its
severity which facilitates the biomechanical injury causation
studies. The detailed successful analysis usually requires
detail information available from different sources such as
Police, EMS, Fire Department, Medical Documents, witness
statements and standard tests as conducted by the government
available free for all the researchers involved in injury
prevention research.
Overall, injury mechanism analysis involves the application of
basic engineering mechanics and clinical description of injuries
for understanding the injury causation inside the vehicle
during accident. The clinical description helps to identify the
boundary conditions, nature of injury producing moments
and force vectors. The knowledge of vehicle interior, contact
evidence and baseline kinematics facilitates the injury analysis.
This data from the injury causation analysis is very important
for the Indian Automobile Manufactures as this facilitate the
development of improved crashworthy designs.
Table 1: Haddon Matrix for Systematic Traffic Accident Injury
Prevention
This matrix provides an opportunity to understand the
behavioural, vehicle related and road related factors influencing
the outcome of an accident in different phases. This systematic
approach to injury prevention is extremely important to
Indian conditions. Vehicle crashworthy design is the single
most important factor which dictates the occupant injury
outcome. The occupant behaviour, attitude, law enforcement
and infrastructure dictate the accident causation on a road. A
simple example of how each factor changes the outcome of
the traffic accident, a seatbelt intervention scheme could be
used to explain this phenomenon. During the impact phase if
the occupant is not wearing the available seatbelt, then this
technological intervention as provided by the manufacturer is
useless in reducing the severity of injury especially in absence
of the SRS (Supplemental Restraint System - Airbag). The
occupant’s attitude and his understanding of seatbelt efficacy

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CHALLENGES IN INDIA
The major challenge in India for the successful injury
causation analysis is the availability of the data. My personal
discussion with the industry personnel during the NATRIP
conference indicated this problem. The unavailability of the
sufficient police records and important scene information
makes it challenging for a successful injury analysis. The EMS
and hospital data are not readily available. Most importantly,
the lack of collaboration between various sectors is required
for successful injury prevention as discussed earlier. Presence
of several data collecting firms creates the challenges of data
ownership and lack of collaboration to solve the single most
important problem India is facing.
The following case study will demonstrate
How the data availability facilitates the injury mechanism
analysis and could help the manufacturer to improve the
injury prevention schemes in their vehicles.
How the failure to follow traffic law caused the fatal
accident.
A perfect example of striking occupant’s attitude factor
and failure of struck vehicles design factor leading to the
fatal outcome.
How the accident is caused by the negligent behaviour of
the striking vehicle driver but the fatal injury outcome is
the direct result of the lack of injury prevention strategies
in the vehicle.
CASE STUDY
The main intention of explaining the case study is to
demonstrate how various documents and information allows
successful identification of the injury mechanism.
This case study will also demonstrate how various factors
influenced the outcome of the accident as explained earlier
by the Haddon Matrix.
Accident Site: This accident occurred in year 2013 in a city
of Potter County, Texas.
Accident location (Fig. 1) was an intersection made up of
three lane one way roads. Roads at this location are straight
and level. The roadway was not wet and the weather was
clear. The road was lighted. Posted speed limit at the location
was 30 mph. Fig. 2 & Fig. 3 shows the accident location
with skid marks visible. The road conditions at the time of
accident were good. The struck vehicle was travelling east on
SE 9th Avenue and the striking vehicle was travelling south
on S pierce st.
Accident Type: Near Side Pure Lateral Impact (Side Impact).
Vehicle Type Involved: Struck vehicle mid-size sedan and
striking vehicle Pickup Truck.
Accident Scene: Police scene investigation was very detailed
with more than 200 photographs of the struck and striking
vehicles. Figure below shows one of the photographs of the
struck vehicle at its final rest position.
Figure 1 : Accident Site Aerial View from Police Data
Figure 2 : Struck Vehicle at the Point of Rest after Extrication
of the Driver
Figure 3: Striking Vehicle at the Point of Rest

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Vehicle Inspection: The availability of accident vehicles
for their inspection is a significant step in injury causation
analysis. This step provides an opportunity to identify the
interior and exterior damage pattern on both the vehicles
indicating the severity of the accident. The interior inspection
is important to identify the physical evidence suggesting the
occupant interaction with the interior. The damage pattern
inside also provides an understanding regarding the motion
of the occupant during the impact phase.
Struck Vehicle Occupant Injury Pattern: The female
occupant of the struck vehicle was 5 ft in height and her
weight was around 129 lbs. No radiology, laboratory or
cardiology test were ordered in the hospital. She was a 61
year old Hispanic woman. She was found unconscious at the
accident site by the EMS personnel at 12:40 am. Her GCS
was 3 on the admission and never improved. On call Doctor
pronounced her dead around 1:21 am in the hospital.
The autopsy as conducted on her next day provides
information regarding her fatal injuries as she sustained in
this side impact. The physical exam of the head and neck
revealed contusion on the left side of the forehead. The
contusion was vertically oriented 3 x 5 cm. The right side
of the forehead shows abrasion of 3 x 2 cm and below the
right side of the lip. The soft tissue of the scalp on the left
side demonstrated hemorrhage in left parietal and temporal
area with focal hemorrhage on the external surface of the
temporalis muscle. This autopsy revealed focal SAH over the
left temporal lobe and over the right parietal lobe. There was
no significant accumulation of subdural hemorrhage. No skull
fracture was revealed. The airway showed no obstruction.
Her thorax revealed purple red contusion on the right pectoral
chest with abrasion near the heart location. The left side of
her chest showed purple-red contusion. Significant hemorrhage
was observed below these contusions.
The autopsy revealed multiple rib fractures on left and right
side at multiple locations. The most significant injury revealed
by the autopsy was the complete transection of the aorta
at the ligamentum arteriosum with significant blood in left
and right chest cavity. In the abdomen, the spleen and liver
showed laceration. The left forearm and left anterior thigh
showed abrasion. The dorsum of the left forearm showed this
abrasion. The autopsy report shows the cause of her death as
blunt force injuries to the torso.
Struck Vehicle Velocity-Time Diagram: The best way to
understand the interaction between the intruding structure
and the near side occupant is to study the velocity-time
diagram. This method can be used to evaluate and compare
the structural performance of two similar class make vehicles.
NHTSA’s database consists of vehicle test data. The database
was used to search and acquire accelerometer data. Fig. 5
below shows the location of accelerometers as fixed on the
left side for LINCAP of the struck car.
Police Accident Narrative:( Fig. 4) “Unit 1 was travelling
SB on S Fillmore St. Unit 2 was travelling EB on SE 9th
Ave. Driver of Unit1 was intoxicated and ran red light at
the intersection of S Fillmore and SE 9th causing the front
of Unit 1 to collide with Unit 2. Driver of Unit 2 died as a
result of the collision. ”
Figure 5 : Accelerometer Data Available from NHTSA Test
The velocity-Time diagram also provides the valuable
information regarding the interior door dynamic travel till it
impacts the occupant’s pelvis and the time they move together
and separates. The Fig. 6 below shows the velocity-Time
diagram as obtained from integrating the accelerometer data
for the struck vehicle from the NHTSA database of LINCAP
crash tests. This data is only analyzed until the first 80ms
around which the barrier reaches zero velocity. The X-axis is
time in seconds and the Y-Axis is velocity in m/sec.
In the Fig. 6 curve 1 (red) is the forward velocity change
of the barrier. Curve 4 (green) is the lateral velocity change
of the test vehicle measured at the CG. The curve 2 (dark
blue) is the interior door velocity and curve 3 (light blue) is
the pelvis velocity. This plot provides following information.
Figure 4 : Police Field Diagram

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The interior door exhibits high rate of change of velocity
and almost reaches up to 12 m/sec.
The pelvis is accelerated to reach velocity exceeding the
barrier impact velocity and almost reach 10m/sec.
Pelvis reaches higher velocity than the lateral velocity
attained by the struck car.
The following side impact crash test as conducted by the
government agency facilitates the understanding of side
structure dynamic response and its interaction with the near
side occupant. This test is very useful in analyzing the injury
producing kinematics of the occupant under investigation. The
interior inspection of the struck vehicle shows various physical
marks and damages made by the occupant interaction.
Struck Vehicle Occupant Kinematic Analysis: In this side
impact accident, the occupant’s body was impacted from the
left side by the intruding door and the truck frontal area.
Because of her proximity to the side door structure, the
inward moving door struck her similar to a punch on the
entire torso the inertia of her body keeps her stationary while
the seat structure and side structure moves towards her. The
high front end of the truck ensures that the intruding door
and other structures simultaneously impacted her entire torso
from the left. Her small height made her entire upper torso
vulnerable to receive a punch from the interior side. The
intruding structure deflected her thorax inboards before her
head started rotating towards the intruding frontal structure
of the truck. The injury on the dorsum of the left forearm
indicates that her left hand was in the path of the intruding
structure. As observed in the velocity time diagram, the pelvis
continued to move inboards with the intruding door and then
separated and continued moving inboards to attain a higher
velocity. This caused the upper torso to incline towards the
left before the pelvis was stopped due to interaction with the
lap belt or console box and caused the upper torso to rotate
inboards. In this accident, the entire front end of the truck
impacted the side and it is unlikely that the pelvis preceded
the contact with the side structure compared to her torso.
The availability of the government test data facilitated the
understanding of near side occupant likely kinematics. The
data and the video are uploaded and available on NHTSA
website for free to be used by various researcher working in
the area of occupant safety.
Occupant’s Fatal Aorta Injury Mechanism: Anatomically
the aorta is located in the mediastinum within the boundaries
of thoracic vertebra and sternum anterior-posterior boundary
and thoracic inlet and diaphragm making superior-inferior
boundary. The aorta begins at the left ventricle of the heart
and ascends where it is known as ascending aorta which
continues as arch of aorta. Three vessels arise from the
superior arch of the aorta. The ligamentum arteriosum holds
the inferior arch to the left pulmonary artery. The descending
aorta is firmly tethered to the thoracic spine by the intercostal
arteries and paravertebral fascia. The arch of aorta is relatively
mobile region. Figure below shows the left lateral view of
the thoracic aorta.
Figure 6 : Velocity –Time diagram for the Vehicle under
Investigation as Obtained from the Government Test Data Base
The autopsy report of the occupant indicates the complete
transection of the aorta at the ligamentum arteriosum (LA).
The mobile region of the aorta remains fixed at LA, therefore
a high velocity impact from left side cause the focal straining
of the aorta at the joint position. The inertial loading of the
mobile arch is dependent on the severity of the side impact.
Researchers in the past have conducted side impact sled test
to analyze the aorta traumatic rupture and its association
Figure 7 : Left Lateral View of Aorta [Netter’s Atlas for ipad].
Time (s)
Velocity(m/s)

6. with padding. The test results indicated that unpadded or
stiff padding lateral impacts produced aorta tear with AIS
4+ injury. The autopsy report of each specimen revealed the
site of injury which was predominantly at the ligamentum
arteriosum. The same study showed no aorta injury with
soft padding tests occurred. This clearly indicates the role of
inertial loading and straining of aorta near the fixed points.
The study was conducted with the pressurized arterial system.
The maximum velocity at which the cadaver impacted the
surface on left side in this laboratory test was 9 m/sec. In
this accident, the occupant received high speed punch from
the side structure on her left side of the torso. The multiple
rib fractures support this fact. This high speed impact caused
the complete transection of her aorta at LA. In this accident,
the side structure impacted her torso in excess of 10 m/
sec velocity as observed from the velocity-time diagram for
LINCAP as obtained from the Government test data.
The occupant sustained the fatal aortic rupture due to high
speed intruding structure and the striking vehicle front. The
unavailability of any energy dissipating structure increased
the severity of the punch from the left side which caused
aorta complete transection. Had this vehicle been equipped
with thorax and head airbag with stronger side structure, she
would have sustained fatal thoracic transection.
How this Injury mechanism knowledge facilitates the
countermeasure development:
As observed from the vehicle inspection, dynamic crash test,
research done in the past and the injury mechanism analysis,
it is evident that the occupant received a high speed punch
from the left side intruding structure causing her fatal injury.
The knowledge of injury mechanism sets up a goal for the
automotive safety engineer. In this case the countermeasure
must address the high speed intruding structure and energy
dissipating mechanism before it is transferred to the occupant.
The strong side structure resisting the intrusion and airbag
system to dissipate energy is the best countermeasure for the
side impact protection. Fig. 8 below as obtained from standard
test conducted by NHTSA shows the ATD interaction with
side thorax, pelvis and head side airbag alleviating impact
loads on the ATD. In this test the side intrusion at the H-point
level was limited to 120 mm compared to 260 mm on vehicle
under investigation and the max speed of intruding structure
was 5.6 m/sec compared to 11.9 m/sec on vehicle involved in
the accident. The TTI (Thoracic Trauma Index) was 48 which
represent less than 5% probability of thoracic AIS+4 injuries.
The countermeasures in the example vehicle as discussed
were fully successful to reduce the injury severity to minor
or moderate level.
Difficulties faced in India for successful accident injury
investigation:
Absence of formal reporting agreements and sharing of
information between police, hospitals and other agencies
Injuries like collisions with fixed and stationary objects,
skid and fall, collision between smaller vehicles are not
reported to police
Mutual understanding between accidental parties, as
involving police would lead to additional costs
Not all Road Traffic Injuries (RTIs) are reported to police
uniformly in all parts of the country
Individuals do not feel the need to report to police unless
the injury is serious, results in legal proceedings and
influence compensation process
Even when injured persons go to police, they are not
officially registered due to paucity of time or the busy
schedule of activities in police stations
Individuals provided care by general practitioners; nursing
homes and smaller health care institutions are not reported
to police to avoid harassment and legal complications
Late hospital deaths due to various complications of road
traffic injuries are not recorded as deaths due to traffic
injuries, but given other causes. Death certificates are not
filled in a systematic and standardized manner in hospitals
across the country
The immediate procedures of burial or cremation based
on local social cultural practices discourage families to
get involved with police preventing Autopsies
Limited manpower and facilities among police often make
reporting very difficult
As there is no reporting practice on all deaths and injuries
to any single agency from all health care institutions,
information is not totally available within the health sector
Figure 8: ATD Interaction with the Stronger Side Structure and
Energy Dissipating Airbags
104

7. DISCUSSION
This paper was intended to show the basic steps and
procedures involved during injury mechanism analysis. This
paper also shows the importance of various data types from
different agencies/group to successfully conduct the injury
causation analysis.
The following basic data as required for injury analysis
follows:
Police Report Police Scene Photographs
EMS Report Fire Dept. Report
Medical Provider complete report
Medical Provider’s complete diagnostic scans
Operative notes
Witness statements
Vehicle crash test reports
Accident vehicle inspection report
Accident vehicle dynamics report (If Available from other
source or Police Record)
The success of injury causation analysis depends on the
detailed data availability as discussed above. The injury
causation analysis is very important for improving the vehicles
occupant protection capabilities. As discussed above the proper
analysis provides information regarding the injury mechanism
which facilitates the design safety engineer to device new
feasible and economical countermeasures for improving crash
performance of their vehicle.
CONCLUSION
Several conclusions can be drawn from the study discussed
in this paper in relation to the traffic conditions in India.
Systematic approach of accident investigation and injury
mechanism analysis is highly recommended to curb the
rate of accidental deaths.
The involvement of the police in reporting the crash and
investigating the scene is mandatory for successful injury
mechanism analysis.
The availability of the accident vehicle for inspection and
other analysis is highly important for successful injury
causation analysis.
The collaboration between different government agencies,
OEM’s and private researchers is highly recommended
for the successful implementation of injury prevention
strategies in India.
OEM’s must focus on real world accident data and injury
causation analysis to improve the crashworthy performance
of their vehicles.
Injury severity analysis is important to set a goal for
reducing the severity or eliminating the injury causation
conditions.
The case study reported clearly indicates the importance of
data from various sources for successful injury mechanism
analysis.
The educational intervention and enforcement via stringent
laws along with more crashworthy vehicle designs are
required for successful injury prevention in India.
Technical
Reference
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