restraint both too low and too far away from the back of the head. ... they are more likely to occur when there is no recorded deformation to seat backs and ... and Head of the Birmingham Accident Research Centre (BARC) which he formed in.
Abstract - Low Speed Rear Impact Collision TOPTEC Monday, August 8, 1994
Rear Impact Crash Characteristics and Occupant Response
Murray Mackay Professor of Transport Safety Birmingham Accident Research Centre University of Birmingham, England
Data is presented to illustrate how the majority of front seat occupants have head positions which are significantly different from the optimal position for limiting neck motions in a rear end collision. The majority of front seat occupants have the head restraint both too low and too far away from the back of the head. Data from a field study will be presented, which describes the velocity change characteristics of rear end collisions and illustrates how the majority of rear end collisions, in which AIS 1 neck injuries are generated, are occurring at velocity change values less than 40 kph. Descriptions are given of the type of seat deformation which occurs in rear end collisions in terms of symmetrical and asymmetrical deformation and separation of various seat components. An analysis of MS 1 neck injuries shows that they are more likely to occur when there is no recorded deformation to seat backs and that some deformation appears to be beneficial. Further descriptions are given relating to the incidence of other injuries to different body regions. The specific mechanisms of neck injuries will be discussed to illustrate how minor neck injuries are one of the major types of injuries in frequency terms, which are occurring to restrained occupants.
Biography - Low Speed Rear Impact Collision TOPTEC
Murray Mackay Professor of Transport Safety Birmingham Accident Research Centre University of Birmingham, England
Dr. Mackay is Professor of Transport Safety at the University of Birmingham in England and Head of the Birmingham Accident Research Centre (BARC) which he formed in 1964. Much of his research has focused on the evaluation of crash protective design and regulations controlling the design of motor vehicles. He has worked with manufacturers and suppliers on the design of safety systems for cars and with various governments in Europe and elsewhere on the development of safety regulations. He is Vice Chairman of the Parliamentary Advisory Council for Transport Safety in the U.K., the organization largely responsible for promoting motor traffic safety legislation in Britain, notably the mandatory use of seat belts in 1983. He holds degrees in Engineering from Birmingham University and the Massachusetts Institute of Technology, and two doctorates in crash injury research and impact biomechanics. He is President of the International Research Council on the Biomechanics of Impacts (IRCOBI), and the first European to have been president of the Association for the Advancement of Automotive Medicine (AAAM), based in Chicago. He is a co-author of the book, "Reducing Traffic Injury - A Global Challenge," which won the Volvo International Safety Prize in 1989. He has written widely on vehicle design and biomechanics of impacts and has testified on product liability matters in half a dozen countries.
ALL (n=1000) Male (n-741) Female (n-237) 300 320 340 360 380 Vertical distance (mm)
1 00
Head to head 80 restraint
90 -
70 60 C.)
50 40 30 —0--- ALL (n=573) 20 -
Male (n=433)
10 -
A----
Female (n=140)
0 50
1 0 0 1 5 0 200 250 300 350 400 Horizontal distance (mm) 1..z."*. •
,- • 4•44.:6-4-.K:S•:•:;:•.: %Y.
_;~:~;:
Distribution of Passenger Car Occupant Fatalities by Principal Point of Impact (FARS 1980)
C. .
CI
N /
) N / N N /
aci
Rear impact distribution(Birmingham 1993)
a" = co
1601 5.8%
671 2.4%
10982 40.0%
1198 4.4%
-i---\--
556 Air 2.0%
3082 11.2%
2954 10.8%
209 0.8%
199 asjr 0.7%
il
125 0.5%
Undercarriage Underrlde
4 528 1.9%
140 (0.5%) 74 (0.3%)
163 0.6%
Noncoffision Unknown
2095 (7.6%) 532 (0.3%)
Delta V of rear impacts (Thomas '82) 90+ 80-89 70-79 60-69
BandedDelta
>
50-59 40-49 111.111 30-39 20-29 10-19 0-9 0
5 10 15 20 25 30 35 40 45 50 55 60 65 70 Number of cases
Delta V of rear impacts (Birmingham '93)
90+ 80-89 70-79
BandedDelta V
60-69 50-59 40-49 nil 30-39
MEM
20-29 10-19 0-9 1 0
10
15
20
Number of cases
25
30
35
40
Rear impact Delta V by injury level (NCSS '80)
100
90 -
80 -
70 a) c.) 60
•
Cumulat ive
•• •
50
All (n=2914)
• 5.•
40 -
AIS 2+(n=81)
or
I .1
AIS 3+ (n=26)
e
30 -
te
•
20 -
FATAL (n=6)
10 -
0 10
20
30
40
60+
50
Delta V (Miles Per Hour)
Maximum injury level of front occupants by ETS (B'ham '93)
1UU
90
BO
• MAIS 1 (n=131)
70 -
..:
MAIS 3+ (n=6)
60
"O.
MAIS 2 (n=22)
50
IT)
.o
E z
40
30
20
10
0-39
40-69
70+
Percentages of Different Types of Impacts
Direction of Impact Force 60
5
Sample size of 5357
r
50
4.) 4a Z.J
L.
30
20
❑
lEa I
5 °CLOCK 6 OCLOCK 7 OCWCK
10
irf
0
Front 50
Percentages of different types of Seat Damage
Side
Rollover
Other
The Effect of ETS on Seat Damage 80
All of this sample suffered some type of Damage
Rear
L
▪
A+13 Asym & Sym bending
•
C - Complete Collapse
•
D - Anchorage Damage
❑
G - No Damage
E+F- Asym & SymtAnohorage 30
Percentage
60
20
10
a
ao. E
0
U
Type of Seat Damage
Symmetric/Anchorage
O 0
20
A Asy mmayriciAnchor age
• a
Anchorage Damage
Symmetric Bending
Asymmetric Bending
t/
40
0
10-19
20-29
30-39
ETS
40-49
>50
Percentage of Different Regions Injured ( in Rear Impacts ) 0.9
Oth
'EZI
Sample size of 356
17.4
Lower Limbs
Probability of Recieving an MS 1 Neck Injury at certain bands of ETS
16
Upper Limbs
40
Injury Region
Torso
Face 30
28
Neck
N
a.)
Head 10
3
20
20 td
The Effect of ETS on the Injuries recieved 100
10 Sample size of 277
other Injuries AIS 1 Neck Injuries only
80
0 o 60
to •
V'
0) -
e/' N
N
(NI
);) C.)
8
a)
*.zr C,)
8 co
u) co
ETS (km/h)
40
20
4 j
0
10-19
20-29
30-39
40-49
50-59
Estimated Test Speed (km/h)
>59
0
U)
100•
[-Effect of Seat Damage on Injuries Sample size of 356
/
80
/ 0 All other InjunesU //
60
.
A1S 1 Neck Injuries
40
C3
E E U,
Type of Seat Damage
Symme tr ic/ Anchorage
c
Asy mmey rIc/ Anchorage
03
15
1
Anchorage Damage
Asymmetric Bending
0
Complete Collapse
20
E 0
The Effect of Degree of Deformation on the Injuries recieved 100 sample size of 356 80
60
,, ,.._____r_i
-./
—
a All other Injuries 0 AIS 1 Neck Injuries only ,...
// c /
/
40
20
0
Low
Medium
High
Failure
Degree of Deformation
No Damage
.
.
.
. N-N•:•9•?:-2.4:::-.;&'••••••
or?
Driver Population by Sex Male Female Not Known Total
742 (76%) 237 (24%) 21 1000 (100%)
ALL (n=1000) Male (n.741) Female (n=237) I
I
I
T
1
300 320 340 360 380 Vertical distance (mm)
•
........................................ "".
:41,4:SY 7.0./9
•••-•••••••••
'
Distribution of Passenger Car Occupant Fatalities by Principal Point of Impact (FARS 1980)
1601 5.8%
10982 40.0%
671 2.4% 1664,
1198 4.4%
556 Ar 2.0%
CD P-11
Top 2324 8.5%
2954 10.8%
199 0.7%
3082 11.2%
Arr 125 0.5%
Ct?
rti
209 0. 8%
528 1.9%
163 0.6%
CD
Undercarriage Underrlde
140 (0.5%) 74 (0.3%)
Noncollision Unknown
2095 (7.6%) 532 (0.3%)
Delta V of rear Impacts (Thomas '82) 90+
80-89
70-79
BandedDelta V
60-69
50-59
40-49
30-39
20-29
10-19
0-9 0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 Number of cases
Delta V of rear impacts (Birmingham '93)
90+ 80-89
.0
70-79
E
BandedDelta
60-69
50-59 40-49 30-39
20-29 10-19 0-9 0
5
10
15
20
Number of cases
25
30
35
40
Rear Impact Delta V by injury level (NCSS '80) 100
00000 •••=1 00000 • 00000 •••••••••••••••
•
90 -
80
70
Cumulat ive
60 r
50
All (n=2914)
te
s e I
40 -
AIS 2+(n=81)
t e
AIS 3+ (n=26)
30 e
20 -
FATAL (n=6)
l t Se
10 -
./ 0 10
20
30
40
50
60+
Delta V (Miles Per Hour)
Maximum injury level of front occupants by ETS (B'ham '93) 100
90
Number of oc cupants
80 70
60
50
40
30
20
10
0-39
40-69
70+
Percentages of Different Types of Impacts
Direction of Impact Force 60
El
Sample size of 5357
50
en t.1
40
30
20
0 5 °CLOCK J 6 °CLOCK II 7 °CLOCK
10
4ap Front Side Rollover Rear Other
Percentages of different types of Seat Damage
The Effect of ETS on Seat Damage 80
All of this sample gut fared some type of Damage
30
■
A+B - Asym d Sym banding
■
C - Complete Collapse
■
D - Anchorage Damage
•
E+ F - Asym & SyntrAnchorage
❑
G - No Damage
Percen tage
Sampe size of 249
10
op
g 3
m of
;
Type of Seat Damage
Symme tric/ Anc horage
.
A 76 o 2 a
Asy mm eyr ic/ Anchor age
Symmetric Bending
Asymmetric Bending
W.7 .• .4
1 0-1 9
20-29
30-39
ETS
40-49
>50
Percentage of Different Regions Injured ( in Rear Impacts ) Other
0.9
Ea Sample size of 356
A
Upper Limbs
16
Injury Region
Lower Umbs
17.4
Probability of Recieving an AIS 1 Neck Injury at certain bands of ETS 40 189
Torso 6.5
Face
30 28
Neck 11.5
Head 10
30
20
The Effect of ETS on the Injuries recieved 10
El All other Injuries AIS 1 Neck Injuries only
0
C1)
V
U)
N
0
C
V"
0
CI)
LI)
CO
ETS (km/h)
10-19
20-29
30-39
40-49
50-59
Estimated Test Speed (km/h)
>59
Cn
0
U)
rEffect
100.
of Seat Damage on Injuries Sample size of 356 1
r/ •
60
0
AU other Injunes
//
AIS 1 Neck Injuries
rr
//
7 -/
40
20
/ .-.,
A.
0
/ /
A
AA
/
//mod ,
co ccn al o_ '5 c i o C CO U a) m U co ...-: @ co E. °.• E , ...
Asy mmetric Bending
Percen tage
80
iii
E m
0
z
u)
cr)
Type of Seat Damage
The Effect of Degree of Deformation on the Injuries recieved 100 sample size of 356
171 All other Injuries AIS 1 Neck Injuries only
80
60
40
20
Low
Medium
High
Failure
Degree of Deformation
No Damage
