www.elsevier.com/locate/forsciint
Available online at www.sciencedirect.com
nal 177 (2008) 90–96
Forensic Science InternatioStudy of injuries combining computer simulation in motorcycle–car
collision accidents
Guo Lei a,*, Jin Xian-Long a, Zhang Xiao-Yun a, Shen Jie a, Chen Yi-Jiu b, Chen Jian-Guo b
a School of Mechanical Engineering, Shanghai Jiao Tong University, Shanghai 200240, Chinab Institute of Forensic Science, Ministry of Justice, Shanghai 200063, China
Received 31 January 2007; received in revised form 9 July 2007; accepted 30 October 2007
Available online 21 February 2008
Abstract
This paper presents the approach of computer simulation to clarify the questions faced by forensic experts about what causes the various injuries
characteristic of two motorcycle victims, including the motorcycle driver and the back seat occupant on the motorcycle, and how to exactly confirm
which one of them is the motorcycle driver. Two typical motorcycle–car accident cases were reconstructed to analyze the movement and the load of
both the motorcycle driver and the back seat occupant in the collision course. In case one, the back seat occupant suffered fatal head injuries when
he fell on the ground after being thrown higher than the motorcycle driver over the top of the car. In case two, the compressive force loaded by the
right tibia of the back seat occupant was larger and more durative compared with the motorcycle driver; the back seat occupant suffered a bursting
fracture injury of his right tibia. These results might be useful for forensic experts in dealing with similar motorcycle–car collision accidents in the
future.
# 2007 Elsevier Ireland Ltd. All rights reserved.
Keywords: Injury; Collision accident; Motorcycle; Computer simulation
1. Introduction
Collision accidents involving motorcycles are frequent in
China, and motorcycle victims easily suffer serious injuries [1].
In 2005, according to the police statistics [2], the number of
fatalities from motorcycle accidents was 20,774 which
accounted for approximately 21% of all traffic accident deaths
in China. Compared with other countries in Europe, the accident
situation involving motorcycles in China was more serious.
In motorcycle–car collision accidents, motorcycle victims
have no protective equipment other than helmets, and the
impact injuries on their bodies vary [3]. The mechanisms and
characteristics of injuries suffered by motorcycle victims are
one of the research emphases for aiding judgment and
prevention of traffic accidents. Forensic experts can offer
some proposals to the police for judging accident responsibility
by observing the characteristics of the injuries and the location
* Corresponding author at: Room 225, Advanced Manufacture Building of
School of Mechanical Engineering, Shanghai Jiao Tong University, No. 800,
Dongchuan Road, Shanghai 200240, China. Tel.: +86 21 34206099.
E-mail address: [email protected] (G. Lei).
0379-0738/$ – see front matter # 2007 Elsevier Ireland Ltd. All rights reserved.
doi:10.1016/j.forsciint.2007.10.011
of the motorcycle victim’s body or by analyzing the autopsy
results. However, they sometimes cannot hypothesize and
explain the cause of these various impact injuries of motorcycle
victims in the collision course of real accidents. In some
complicated motorcycle–car collision accidents in China, for
example, there are two motorcycle victims that one is the
motorcycle driver and the other one is the back seat occupant on
the motorcycle. It is difficult to objectively judge by forensic
conclusions which one of them is the motorcycle driver, and
therefore the guilty party to be convicted in court, when this
type of accident happens.
Computer simulations of motorcycle–car collision accidents
provide an effective approach [4,5] to reveal the mechanism of
injuries of motorcycle victims and to solve the doubts faced by
forensic experts. The collision course of accidents can be well
reconstructed in three-dimensional space by establishing
mathematical models of cars and human bodies, and the
movement and the load of motorcycle victims’ bodies in the
collision course can be simulated by using computer
simulation. The simulation results are helpful for forensic
experts to analyze and discover the cause of various impact
injuries, and assist the police in judging who should be held
responsible for the accident.
Fig. 1. The multi-body system of bodies connected by kinematic joints.
G. Lei et al. / Forensic Science International 177 (2008) 90–96 91
This paper presents the approach of computer simulation to
reveal the cause of various impact injuries characteristic of
motorcycle victims by reconstructing the collision course of
two typical motorcycle–car accidents. Both accident cases
concern two motorcycle victims, the motorcycle driver and the
back seat occupant on the motorcycle, and the characteristic
injuries are relevant to the different movements and load of
their bodies in the collision course. It can be confirmed which
one of them is the motorcycle driver who is responsible for the
accident, by analyzing the injuries of their bodies under
forensic study combining simulation results.
2. Methods
The multi-body dynamics method is presented using one of the most useful
computer programming methodologies in the world, and it can simulate the
dynamics response of complex multi-body systems. A multi-body system
generally consists of rigid and flexible bodies joined together by kinematic
joints (e.g., revolute or translational joints) or force elements (e.g., springs and
dampers), and the presence of these kinematic joints is defined by means of
global and local coordinate reference systems in such a model (Fig. 1(a)). It is
sufficiently flexible to construct a multi-body model of a human body or vehicle
with various kinematic joints and discrete bodies of particular size and shape
(Fig. 1(b)).
MADYMO [6–9] (mathematical dynamic model) is a software of the multi-
body dynamics method which has been most widely applied in injury biomecha-
nics and accident reconstruction [10–12] involving many means of transport such
as cars, motorcycles and bicycles. It uses numerical algorithms (e.g., modified
Fig. 2. Damage to the ca
Euler or Runge–Kutta) to predict the motion of systems of bodies connected by
kinematic joints, based on initial conditions and the inertial properties of the
bodies. It is convenient to use the database of human body models developed by
TNO (Netherlands Organisation for Applied Science Research) and EEVC
(European Experimental Vehicles Committee), including the Hybrid III dummy
and pedestrian models in this software. These human models are available to
simulate occupants in various kinds of accidents.
In this paper, the multi-body model of cars and motorcycles in both accident
cases are set up according to their real shape and mass in MADYMO. The
contact characteristics of the structure of the car and motorcycle in the collision
course proposed by Motoaki [13] are used in the present study. The sitting
Hybrid III dummy models in the database are used to simulate the motorcycle
driver and the back seat occupant on the motorcycle, and the contact char-
acteristics of the dummy model are examined by TNO. Some modifications of
the dummy are performed on mass distribution and body posture according to
the body characteristics of the motorcycle victims in each accident.
In case one, the motorcycle suddenly crashed into the left rear of the car
when the car was waiting for the traffic lamp to convert from red to green at the
town crossroad. The damage of the impacted car and motorcycle are shown in
Fig. 2. The left rear taillight and bumper of the car were shattered, presumably
by the motorcycle front cowl and front wheel. The left rear windshield of the car
also was shattered, presumably by the motorcycle driver or the back seat
occupant on the motorcycle when his head impacted the rear windshield. The
front cowl of the motorcycle was smashed to pieces, and some green paint of the
car body adhering to the front shock absorber of the motorcycle could be
observed.
The two motorcycle victims, the motorcycle driver and the back seat
occupant on the motorcycle, did not wear helmets in this case. They both
were thrown forwards from the motorcycle seat and fell to the ground at an
unequal distance. The draft of the final accident scene drawn by the police is
shown in Fig. 3, and the location of victim A and victim B were explicit when
the collision happened. The distance between victim A’s head and the center of
the motorcycle front wheel was 715 cm, and the distance between victim B’s
head and the center of the motorcycle front wheel was 105 cm. Victim A mainly
suffered fatal head and brain injuries, contusion and laceration of the right face,
abrasion and bruising of limbs (Fig. 4(a)), and died at the location of the
accident. Victim B suffered serious injuries, contusion and laceration of the
calvarial scalp and left face, abrasion and bruising of the mandible, limbs and
perineum (Fig. 4(b)), and survived in the hospital. By observing the damage of
the left rear of the car, forensic experts thought that the motorcycle driver might
easily suffer abrasion and contusion of the left face and mandible from the
impact of the left rear windshield of the car, crush injury of the perineum from
the impact of the gasoline tank of the motorcycle, and the back seat occupant on
the motorcycle might be thrown farther away from the motorcycle than the
motorcycle driver when the collision happened. Therefore, they could presume
that victim B was the motorcycle driver who should be responsible for the
accident by contrasting victim B’s injuries with victim A’s. However, victim B
denied the charge of being the motorcycle driver himself and did not admit guilt
r and the motorcycle.
Fig. 3. The draft of the final accident scene.
G. Lei et al. / Forensic Science International 177 (2008) 90–9692
in court. There was still some debate about which of the two victims was the
motorcycle driver, and it could not be absolutely confirmed by the police.
In case two, the motorcycle suddenly passed the crossroad when the traffic
lamp was red, and then the car crashed into the right side of the motorcycle. The
damage of the impacted car and motorcycle is shown in Fig. 5. Deformation of
the front left bumper, hood edge and bonnet of the car could be observed,
presumably caused by the motorcycle driver or the back seat occupant on the
motorcycle when his right crus impacted the bumper, his thigh impacted the
hood edge and his hip impacted the bonnet. The external plastic shell of the
motorcycle body and the footplate on the right side, thought to be impacted by
the car front structure, were smashed into pieces.
Both motorcycle victims, the motorcycle driver and the back seat occupant,
also did not wear helmets in this case. The final accident scene was not drawn by
the police because one survival victim escaped from the location of the accident
and another victim was immediately sent to the hospital. The motorcycle victim
in the hospital died within several hours; he mainly had suffered fatal head and
Fig. 4. Injuries to the two motorcycle vic
Fig. 5. Damage to the ca
brain injuries, right tibia fracture and some body bruises. For the analysis of the
right tibia fracture of the dead motorcycle victim, the anatomy of his right crus
was performed by forensic experts in the Institute of Forensic Sciences,
Ministry of Justice in Shanghai. The bursting fracture of the central section
of his right tibia could be observed, and the length of the bone crack was more
than 5 cm as shown in Fig. 6; it was thought to be severely impacted by the car
bumper. By observing the deformation of the car bumper and the motorcycle
steel body, forensic experts thought that the back seat occupant on the motor-
cycle might easily suffer serious injury of his right crus from the crush between
the car bumper and the motorcycle steel body in the collision course, and the
motorcycle driver might not suffer such serious injury of his right crus.
Therefore, they could presume that the escaping motorcycle victim, who did
not suffer the fracture injury of right tibia, was the motorcycle driver. However,
this supposition needed to be confirmed for a correct judgment of the accident.
3. Results
According to the investigation materials shown by the
police, the situation where the impact velocity of the
motorcycle was 52 km/h and the car instantaneously immobile
was simulated in case one, and the situation where the impact
velocity of the car and motorcycle were about 55 and 20 km/h,
respectively was simulated in case two.
For case one, the simulation result of the final accident
scene is shown in Fig. 7, and the simulation result of the
collision course is shown in Fig. 8. The distance between
tims: (a) victim A and (b) victim B.
r and the motorcycle.
Fig. 6. Fracture injury of the right tibia of the dead motorcycle victim.
G. Lei et al. / Forensic Science International 177 (2008) 90–96 93
victim A’s head and the center of the motorcycle front wheel
was 617 cm, and the distance between victim B’s head and
the center of the motorcycle front wheel was 120 cm, as
shown in Fig. 7. Compared with the draft of the final accident
scene shown in Fig. 3, the simulation result in Fig. 7 was
accordant and more visual. In Fig. 8, the front cowl and
wheel of the motorcycle contacted with the left taillight and
bumper of the car at 50 ms, and the motorcycle driver and the
back seat occupant were thrown forwards from the
motorcycle seat on the inertial velocity effect. The
motorcycle driver’s head smashed the left rear windshield
of the car, bruised and contused his left face and mandible by
the edge of windshield at 100 ms, and his shoulder and thorax
contacted with the rear body of the car so that the forward
movement of his body was blocked. The back seat occupant’s
head did not directly impact the car body, but his right face
was bruised by the side pillar nearby the rear windshield at
200 ms, and then his body was thrown high over the car top at
300 ms, and his right hip and thigh contacted with the car top
when he dropped from the air.
Compared with the impact movement of the motorcycle
driver, the back seat occupant was thrown higher in the air and
fell to the ground at a farther distance so that he suffered more
serious brain injuries when he hit his head on the ground. The
fatal head injury was the cause of death of the back seat occupant.
Fig. 7. Simulation result of the final accident scene of case one.
That victim B was the motorcycle driver could be undoubtedly
confirmed by analyzing the simulation result.
For case two, the simulation result of the collision course is
shown in Fig. 9. The bumper of the car contacted with the right
side of the motorcycle body and the right crus of the motorcycle
driver and the back seat occupant at 20 ms. The movement of the
right crus of the back seat occupant was blocked by the
motorcycle body, and his right crus was crushed between the
bumper of the car and the steel shell of the motorcycle body. The
right crus of the motorcycle driver was struck away instanta-
neously by the car bumper. The right hip and thigh of the back
seat occupant impacted the hood and hood edge of the car, which
led to the bruise injuries. Both their bodies moved to strike the
bonnet of the car in the collision course, but the motorcycle driver
was struck away from the car because the movement of his right
crus was not blocked by the motorcycle body.
The fracture of the right tibia was the injury characteristic
that distinguished the back seat occupant from the motorcycle
driver in this case. The simulation result of the compressive
force loaded by their right tibias is shown in Fig. 10. The
maximum value of the compressive force loaded by the right
tibia of the back seat occupant was more than 10 kN, and that
loaded by the right tibia of the motorcycle driver was
approximately 8 kN. Moreover, the right tibia of the back seat
occupant endured the compressive force above 4 kN average
over 20 ms in the collision course, but the right tibia of the
motorcycle driver only endured a peak value of the impulse
force less than 5 ms. According to the research of Yang [14] and
Kress [15], it might lead to the fracture of the tibia when the
peak value of compressive force loaded by the victim’s tibia
was more than 4 kN, and the probability of bone fracture was
influenced by the victim’s age and sex, the weight downward
loaded by the victim’s lower limbs and the impact velocity of
the car. In this collision accident, both motorcycle victims were
young men, and it could be observed that their lower limbs did
not support weight downward when they sat on the motorcycle.
However, the back seat occupant on the motorcycle suffered a
tibia fracture because his right tibia had endured a big
Fig. 8. Simulation result of the collision course of case one.
G. Lei et al. / Forensic Science International 177 (2008) 90–9694
compressive force much longer by contrast with the right tibia
of the motorcycle driver in the collision course. The cause of the
bursting fracture of the right tibia of the back seat occupant was
explicit as a result that his right crus was sustainedly crushed
between the car bumper and the motorcycle steel body in the
collision course. Therefore, it had been rightly confirmed by the
simulation result that the motorcycle victim whose right tibia
did not suffer serious fracture injury was the motorcycle driver.
4. Discussion
By reconstructing the two typical motorcycle–car collision
accidents, it could be found that the different impact
movements and the unequal load of the motorcycle driver
and the back seat occupant were the causes of their various
injuries, and in both cases the back seat occupants had died of
head injuries because they did not wear a helmet.
In case one, the motorcycle driver and the back seat
occupant had suffered injuries of varying severity and of
varying locations on their head, face and mandible as a result of
their different impact movements. The motorcycle driver’s
head smashed the rear windshield of the car, leading to
abrasion and contusion of his mandible and left face. The back
seat occupant’s right face was bruised by the side pillar nearby
the rear windshield, and his body was thrown high in the air so
he suffered more serious brain injury than the motorcycle
driver when he fell from such a height and hit his head on the
ground. Perineum injury of the motorcycle driver was also a
characteristic injury, a result of the gasoline tank of the
motorcycle crushing his perineum.
Fig. 9. Simulation result of the collision course of case two.
G. Lei et al. / Forensic Science International 177 (2008) 90–96 95
In case two, the load of compressive force on the right tibia of
the motorcycle driver and the back seat occupant was not equal so
that they suffered injuries of varying severity of their right tibias.
The back seat occupant suffered a bursting fracture injury of the
right tibia because his crus was forcibly crushed between the car
front bumper and the motorcycle steel body and endured a
durative compressive force. The motorcycle driver’s right crus
did not suffer such serious injuries because the movement of his
right crus was not blocked by the motorcycle steel body in the
collision course. If it was not a light motorcycle, but a race
motorcycle like that in the case one, the motorcycle driver might
also have suffered serious right tibia injury.
Motorcycle victims easily suffer head, face and neck trauma
in crashes [16], and the motorcycle driver might suffer
perineum injury according to different types of motorcycles.
Head injury led to the death of motorcycle victims when they
Fig. 10. Compressive force loaded by the right tibia of the motorcycle driver
and the back seat occupant in case two.
G. Lei et al. / Forensic Science International 177 (2008) 90–9696
did not wear a helmet [17,18], and the fracture of long bone was
another serious injury to motorcycle victims [19]. These
previous studies were in agreement with the findings of the two
cases in this paper. Computer simulation of collision courses
could help forensic experts and the police discover the cause of
various injuries of motorcycle victims in each case.
5. Conclusions
This paper reconstructed the collision course of two typical
motorcycle–car accident cases, and simulated the movement
and the load of the motorcycle driver and the back seat occupant
on the motorcycle in the collision course by using computer
simulation. It was demonstrated that computer simulation is an
effective approach to clarify the cause of various injuries
characteristic of motorcycle victims in forensic literature.
Forensic experts and the police distinguished the motorcycle
driver from the back seat occupant without any doubt by
combining the analysis of their injuries with computer
simulation results. Other collision situations of real motor-
cycle–car accidents should be researched for the analysis of
victims’ injuries, and the experiences of the two cases in this
paper might be useful for forensic experts in dealing with
similar motorcycle–car collision accidents in the future.
Acknowledgements
The authors gratefully acknowledge the financial support
from the National Natural Science Foundation of China
(No. 50705058) and the National High Technology Research
and Development Program of China (863 Program) (No.
2007AA11Z234).
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