-30-

HEAD AND NECK I NJURIES TO CAR OCCUPANTS

WEARING SAFETY BELTS I N FRONTAL COLL I S I ONS

G . GRI ME , Traf f i c S t udies Group , Hn ivers i ty Co l l e ge Lon don .

I t i s widely recogn i sed that restraint s yst ems f o r car occupan t s should be des i gned to protect at least three imoortant areas of the body - the head , the ehest , and the l e gs . As ye t , however , there are no gene r a l l y agreed inj ury c r i t e r i a in terms o f phy s i c a l quan t i t i e s ( e . g . force or acce l eration ) which , when measured on represen t a t ive dummies protected by res t r a i n t systems , shoul d n o t be excee ded under speci f i e d t e s t con d i t ions . The most import ant suggest ions for such c r i t e r i a were embodied in the proposed Ameri can Federal Mo tor Veh i c l e Safety S t andard No 2 0 8 and i t s amendments , and be cause of their probab le wor ld­wide i n f luence i f f in a l ly con f i rme d , they have been extensively tried out i n veh i c l e crash tests , and , perhaps in modi f ie d form , are l i ke l y to form t h e b a s i s f o r future European a s we l l as Ameri can regulat ions . For head inj ury , with wh i ch this p aper is concerned , the proposed Ame r i can criteria are exp ressed in terms of resul t an t accelerat i on s , measured i n the he ads o f dummies , in 30 m i l e / h fron t a l b ar r i e r tests ; these acce lerat ions must not be exceede d , even when no impact o f the head with the i n t e ri o r o f the car o c curs .

However , expe rien ce o f the performance o f 3 p o i n t lap­and-di agona l safety b e l t s in real accidents has raised doubts as to whether the r i sk o f head inj ury without head impact i s great enough t o j us t i f y t h e app l i cat ion o f a head i n j ury cri terion in such cases ; i n dee d , any such requirement may actua l ly ret ard the development of systems des i gned to be e ff e c t i ve at h i gher impact speeds than 30 mi l e / h . I n the present note , the inj uries suffered b y a s amp l e of b e l t wearers in fron t a l i mpacts are described , and the resul t s are d i s cussed with spe c i a l refere n ce to the probab i l i ty of head and n e ck inj ury .

I n an e a r l i e r p aper by t he author ( l ) an an a l y s i s was made of inj uries to be l t wearers in about 7 5 0 acciden ts ; nearly 90 per cent o f the b e l t s were o f the 3 point l ap-and-di agonal type . For the present note , spe c i a l attent ion has been paid to the data on fron t a l imp acts described in t he reports wh i ch formed the b a s i s o f the e a r l i er p aper , and to about 1 0 0 l ater report s . A l l these reports were returned to the safety belt manufacture r by mot o r i s t s who had been wearing safety b e l t s in acciden t s . Rough est imates o f v e l o c i t y change were made for a l l the fron t a l impacts which resul ted in inj ury t o a b e l t wearer , mak i n g u s e of t h e reported c i r cums t an ces o f the

- 3 1 -

acciden t s , t h e we i ghts and speeds o f the veh i cles , and the extent o f the damage to the cars . I n many o f t he more serious acci den t s the o r i g i n a l repor t s were supplemen t e d by more lengt hy accoun t s obtained by corresponde n ce . I n no case , however , was i t possible to examine veh i c les or acc i dent s i t e s .

The est imated ve locity changes ranged from 1 0 to 4 5 m i l e / h ( 1 6 to 72km/ h ) , and i n Tab les 1 and 2 the resu lts have been d i v i de d i n t o those above and be low 30 m i l e / h ( 4 8km/h ) .

The i n j uries t o the b e l t wearers were c l as s i f ied i n accordance w i t h TRRL n o t e LF1 30 ( I ssue 3 ) . There was sornet irnes di f f i cu l t y i n d i s t i n guishing between the three categories o f inj ury to t h e head an d face ; f o r exarnp le , a l l concus s i ons were c lassed as moderate i n j ur i es , whereas some rniRht have been rnore corre ct ly c l assed as rninor or severe ; s imi lar l y , alme s t a l l l acerated faces and heads were c l assed as rninor , when some rnight rnore accuate ly have been p laced in the moderate c l as s . None of the con clusions of the paper are affected by t h i s b lurr i n g of the boundaries ; and the d i f f i cu l t y d i d not arise for o ther parts of the body .

Tab l e 1 surnmarises the inj uries t o the d i f ferent regions o f the body , in terms o f mino r , moderat e , and severe i n j uries . There was o n l y one death , o f a p assenge r . I nj ury accured t o one o r both f ront seat o c cupan t s wearing 3 p o i n t lap-and di agonal b e l t s in 1 8 2 f ro n t a l i mp a ct s ; l � l were j udged t o have occurred at ve l o c i t y changes b etween 10 and 2 9 mi l e / h ( 1 6 and 47km / h ) and 5 1 between 30 and 4 5 rn i l e / h (4 8 and 72km/ h ) . In the 1 8 2 impacts t here were 7n head i n j uries , 1 8 o f whi ch were j udged to be of greater than minor sever i t y . As m i ght be expecte d , t he proportion o f the rnore serious inj uries was greater at ve loc i t y changes above 30 rni l e / h than b e low .

The he ad inj uries are con s i dered i n rnore d e t a i l i n Tab le 2 , i n whi ch descr i p t ions are given o f head inj uries o f greater than minor seve r i t y a n d i n Tab le 3 , w h i c h gives det a i l s o f a c c i dents i n wh i ch concus s i on occurred wit hout accornpanying head i n j ur i es such as cuts and hruises . I n the 5 1 accidents whi ch accurred at ve locity changes over 30 m i le / h , there were , of course , 5 1 drivers and , i n addi t ion , 2 7 front seat passengers , a l l weari n g 3 point l ap-and-di agonal b e l t s . 2 8 drivers had head i n j ur i es , 10 of wh i ch were j udged to be of greater than rninor sever i t y ; o f these more serious head inj uries 8 inc luded con cussion ; every case of con cussion was accornpan i e d by other inj uries ( cuts , bruises e t c ) to head or f ace , i n d i cating that the head had s t ruck sorne obj ect in front of the driver , probab l y p ar t o f t h e s t e e r i n g whee l . On l y 4 o f t h e 2 7 front seat passengers had head inj uries , in cluding one case of concussion wi thout any o ther head inj ury . This occurred in a very severe co l l i s ion ( see Tab le 3 , case No 3 3 5 ) , in whi ch the p assenger sust ained a f ractured spine as we l l as concuss ion , both

-32-

at t r ibuted to f ron t a l i ntrusion i n t o t he passen ger compartmen t .

I n the 1 3 1 imp acts at ve l o c i t y changes j udged t o be below 30 mi l e / h , 129 of the 1 3 1 drivers wore b e l t s ; t he y were accompanied by 70 front seat p assen gers wearinß b e l t s . 31 dr ivers had head inj uries of which 3 were j udged to be of greater than minor s everi ty ; only one o f these ( see Tab l e 3 , case No 5 1 4 ) involved concuss ion wi thout o ther head inj ury , and t h i s was repor t e d as due to impact w i t h the s i de win dow . The 7 0 f ront seat passengers also had 3 head inj uries j udged t o be o f gre ater than minor seve r i ty - a l l ins tan ces o f concuss ion wi thout other head i n j ury . I n 2 o f the 3 cases t he reports suggest that concussion was the resul t of impact o f the head against a s o l i d obj e ct . Case No 2 7 6 was a low speed i n tersect ion acc i dent ( ve lo c i t y change about 1 0 mi l e / h ) in which the car p robab l y rotat e d , resu l t i n g in concussion due to co l l i s ion of heads , as reported ; i n case No 6 9 7 , an a c c i dent at a h i gher ve l o c i t y change , both b e l t e d occup ants were l ike l y t o have been l oaded f rom behind by t he two passengers i n the rear seat , giving r i se to f a c i a l and knee inj uries to the driver , and caus i n g breakage o f the shoulder strap o f the p assenger ' s b e l t , w i t h resu l t i n g inj uries from j ackn i f ing over t he l ap strap . On l y an case No 559 was no exp l anat i on of the concuss ion gi ven i n the report or sugge sted b y the account o f the accirte n t , although i t i s worth n o t i n g t hat the dr i ver was u n i n j ure d . I t is s i gn i f i cant that no neck inj uries , even s l i ght ones , were men t ioned in any of the cases described in Tab l e 3 , and i t wou l d appear very un l ike l y that concussion due t o a j erk from a safety b e l t coul d o ccur wi thout any s i gn of neck inj ury .

To sum up , i n a l l 1 8 2 fron t a l impact s , involving 2 7 7 car occup an t s wear ing s a f e t y b e l t s , there were 1 3 cases o f concuss ion , a n d o n l y i n one case i s there any probab i l i t y that concuss ion mi ght have occured wi thout head impact .

There was on l y one n e ck i n j ury of greater than minor sever i t y , - a b roken neck , probab ly caused b y imp act f rom the passenger in the rear seat , who was k i l l e d . S t i f f or s t r ained necks were reported i n 21 i n s t an ces ; and none o f these neck inj uries was associated with a head inj ury . I t appears that one f i n ds ei ther neck i n j u r i es or head inj uries , but very rarely both t o ge ther . Neck inj uri e s probab l y only o c cur when the res traint system o f b e l t an d car work corre c t l y together to restrain the occupant without head con t act ; when head con t act occurs the dece lerat i n g forces whi ch the neck i s capab le of exe r t i n g are not brought f u l l y into p l ay .

I n Tab l e 1 t he numbers o f head and f ace inj uries are given sep arate l y for the driver and the fron t seat p assenge r . I f inj uries o f a l l sever i t ies are counted , drivers suf fered 59 and p assengers 1 7 head an d f ace inj uries . S i n ce the numhers o f drivers and p assengers at risk were respe c t i v e l y 1 8 0 and 9 7 ,

- 33-

t he head inj uries per o ccup an t were 0 . 3 3 for the dri ver and 0 . 1 8 for the p assenger - a s i gn i f i cant d i f ference . Th i s ten den cy f o r the driver t o be inj ured more often i s also shown by the f i gures for greater than minor head and f ace i nj ury , - 1 4 for the driver and 4 for the passenger .

The obvious d i f f erence be tween the surroun di ngs of the d r i ver and f ront seat passenger is the p resence o f the steering assemb ly i n front o f the drive r , and many o f the reports men t i on the steering wheel as the obj ect wh i ch caused the dri ver ' s head inj ury . Whe ther the presen ce o f the whee l is enough in i t se l f to accoun t for the greater frequency o f head inj ury i n the dr i ve r , or whe ther the who l e steering assemb ly , by l im i t i n g the forward movement at the h i p , produces a greater tendency to j ackn i fe i n the driver t han the p assenger i s a que s t ion to wh i ch t he p resent in ves t i ga t i on does not provide an answer .

I t might pe rhaps be expected that the steering assemb ly wou l d also i ncrease the frequency o f ehest and rib inj ury . The f i gures in Tab le 1 , however , suggest that i f there is any e f fe c t at al l , it is in the oppo s i t e d i rect ion . For inj uries o f all severi t ies , the i nj uries per driver were 0 . 26 and for the passenger 0 . 3 2 ; for greater than minor inj uries the i n j uries per o ccup an t were respe c t i ve l y 0 . 0 7 and 0 . 1 4 , but the d i fference is not s i gn i f i can t at t he 5 per cent leve l .

Final l y , i t i s emphas ised that no deduct i ons as to the ove r a l l e f f i ciency o f safety b e l t s should b e made from the dat a g i ven i n this p aper , s i n ce all the impacts con s i dered were ones wh i ch resulted i n inj ury t o one o r more b e l t e d f ront seat occupan t s . The numerous i n ves t i ga t i on s wh i ch h ave been made of the e f f i c ie n cy of s af e t y b e l t s i n p reven t i n g i n j ury almost a l l show that substan t i a l reduct i ons in inj ury , p a r t i cularly in serious inj ury , resul t when b e l t s are worn .

Con c lusions

1 . Th i s survey of 1 8 2 fron t a l impacts suggests that when a car occup ant wearing a 3 point l ap - an d- d i agonal safety belt suffers concuss ion i n an accident of this type , i t is almost always the result o f impact o f the head with the i n s i de o f the car .

2 . There was also e v i dence t hat t he neck inj uries that occur in such imp acts are i n f requent and usu a l l y minor one s , and are un l ike ly to be accomp an i e d b y head inj ury .

3 . The resu l t s do not p ro v i de any support for a head inj ury c r i terion for wearer s of safety b e l t s o f the type cons i dere d , except in cases where the head s t r ikes the i n s i de o f the vehi cle .

-34 -

Acknowle dgeme n t s

Thanks are due t o Bri t ax L t d for mak i n g t h e data ava i l ab l e , and to the Transport and Road Research Laboratory for the f inancial support which enab led the p aper to be prepare d .

Re f erences

1 . Grime , G. ' A ccidents and i n j ur i es to car occup an t s we ari ng safety b e l t s ' . Automob i l e Engineer 1 9 n 8 ( Ju l y ) .

Ve

loc

ity

ch

ang

e

(mil

e/h

)

10-

29

(1

6-

47

k

m/h

)

30

-4

5

(48

-7

2 k

m/h

)

10-

45

(1

6-

72

km

/h)

Tab

le

1.

Inju

rie

s

to w

ea

re

rs

of

se

at

be

lt

s

in

fro

nt

al

im

pa

ct

s.

Nu

mb

er

Se

ve

rit

y

of

o

f

imp

ac

ts

inj

ury

Se

ver

e

Mo

de

ra

te

131

Min

or

Sev

er

e

Mo

de

ra

te

51

�in

or

Sev

er

e

Mo

der

ate

182

Min

or

Hea

<l

Ne

ck

an

d

f ac

e

0 i<

6 C 3

I :3 ) 1 1

0 0

38

(28

/10

)16

3(3

/0

) 1

9(8

/1)

0

20

(17

/3)

5

3(3

/0

) 1

15

(11

/4

) 0

1 1 5

8(4

5/1

3)2

1

1

PA

RT

S IN

JU

RE

D

Sh

ou

lde

r

Ch

est

[

nte

rn

a

an

d

br

ga

ns

rib

s

0 0

0 *

3

14

(6/8

) 2

·· -n

33

(22

/11

) 0

0 4

(1/3

) 3

+

7 9

(6/

3)

0

2 1

8(1

2/6

) 0

0 4

(1/

3)

3

10

23

(12

/11

2

8 5

1(3

4/1

7

0

* (3

/3

) e

tc

. d

en

ote

(D

riv

er

/Pa

ss

en

ger

) in

jur

ies

+

O

ne

pa

ss

en

ger

ki

lle

d

Arm

s

0 4 '-

·---

--1

3

0 7 -

--

10

0 11

23

Le

gs

an

d

kn

ee

s

0 7 -

---

-72

3 6 �

-- 32

3

13

104

Cu

ts,

bru

ise

s

an

d b

elt

b

ru

ise

s

0 0

60

(30

/30

)

0 0

25

(15

/10

)

0 0

85(4

5/4

0)

1 w

Ül

1

Ve

loc

ity

ch

an

ge

(m

il

e/h

)

10-

29

(l

ß-

47

k

m/h

)

30-

45

(48

-7

2

km

/h)

Tab

le

2.

He

ad

in

ju

rie

s o

f g

rea

ter

th

an

min

or

se

ve

rit

y

Num

be

r

Nu

mb

er

Ca

se

In

jur

ies

o

f

imp

ac

ts o

f

inj

ur

ies

No

. c

au

sin

g

of

g

rea

ter

D

riv

er

F

ro

nt

se

at

pa

sse

ng

er

in

ju

ry

than

m

ino

r

�P.VP.ritv

1

85

Lo

st

se

ve

ra

l te

eth

; B

rok

en

left

c

lav

icle

; eh

es

t b

ru

ise

s.

ehe

st

br

uis

es

. 2

7f'

TJ

nin

jur

ed

C

on

cus

sio

n;

br

uis

ed

le

ft

sh

ou

lde

r;s

ea

t b

elt

cu

ts

.

131

32

43

7

Lo

st

fr

on

t te

eth

; cu

t c

hin

.

55

9

Un

inju

red

. 8

lig

ht

con

cuss

ion

.

69

7

Fa

cia

l la

ce

ra

tio

ns

; C

on

cuss

ion

a

nd

se

ve

re

b

ru

ise

d k

ne

es

. b

ru

isin

g.

514

C

on

cus

sio

n;

inju

re

d

ste

rn

um;s

pin

al

inju

rie

s

169

F

ac

ial

lac

er

at

io

ns

Fa

cia

l la

ce

ra

tio

ns

. an

d co

ncu

ss

ion

. .

28

2

Co

ncu

ss

ion

; b

ro

ke

n

tee

th

; c

uts

a

nd

a

br

asi

on

s to

s

ca

lp

an

d

kn

ee

s;

br

uis

ed

ha

nd

s,

arm

s a

nd

rib

s;

cra

cke

d b

on

e

in

lef

t h

and

. 5

1 30

30

2 S

ev

er

e

fac

ial

inj

ur

ies

a

nd

br

ok

en

n

os

e.

33

5

Fr

act

ur

ed

c

lav

icle

; C

on

cus

sio

n

and

fra

ctu

re

d

gr

aze

d

leg

. s

pin

e.

--

1 w

°'

1

Ve

loc

ity

Nu

mb

er

ch

ang

e

of

imp

act

s (m

ile

/h)

cau

sin

g

inju

ry

30-

4f)

(co

nt

.)

Ta

ble

2

. (c

on

tin

ue

d)

Nu

mb

er

Ca

se

Inju

rie

s

of

in

ju

rie

s N

o.

of

gr

ea

ter

D

riv

er

F

ro

nt

se

at

pa

ss

en

ge

r

tha

n m

ino

r

se

ve

rit

v

390

C

on

cu

ss

ion

and

la

cer

at

ion

s.

40

1 C

ut

he

ad

; s

li

ght

Be

lt

br

uis

es

. co

ncu

ssio

n;

inj

ure

d

lef

t k

ne

e.

40

9

Fa

cia

l i

nju

rie

s;

Br

ok

en

cl

avic

le

and

sl

igh

t

con

cus

sio

n;

wr

ist

. s

ev

er

e

ehe

st

bru

isin

g.

fl4

4

He

ad

in

ju

ry

; u

nc

ons

cio

us

.

1012

F

ac

ial

inj

ur

ies

to

jaw

In

jur

ies

to

jaw

a

nd

te

eth

; a

nd

te

eth

; r

igh

t

leg

fr

ac

tur

ed

c

lav

icle

a

nd

b

ro

ke

n

in

3 p

lace

s.

an

kle

. 10

16

Fa

cia

l b

ru

isin

g a

nd

B

lack

e

ye

; b

ru

ise

d k

ne

es

. c

on

cu

ss

ion

; b

rok

en

ri

ght

th

igh

&

left

s

hin

.

1019

F

ra

ctu

re

d

jaw

; d

am

ag

ed

.Br

uis

ed

. te

eth

; c

ut

chi

n;

conc

us

sio

n;

cut

rig

ht

k

nee

.

1 w

'..J

1

Tab

le

3.

Ac

cid

en

ts

in

wh

ich

con

cus

sio

n w

as

·re

pö

rte

d w

i th

ou

t o

the·

r h

e·a

d

inj

ur

ies

.

Ca

se

V

eh

icle

s

· De

sc

rip

tio

n

of

Inj

urj.

es

No

. ··a

cc

ide

nt

Dr

ive

r

Fro

nt

se

at

pa

ss

en

ge

r

27

6

196

5 T

riu

mph

Oth

er

ca

r cr

os

sin

g

Un

inj

ur

ed

. B

ru

ise

d

lef

t s

ho

uld

er

; H

er

ald

12

00

. tr

af

fic

lig

hts

a

t s

ea

t b

elt

cu

ts;

Ca

r.

re

d w

as

hit

by

co

ncu

ss

ion

due

to

Tr

ium

ph

at

rep

or

te<l

co

ll

isio

n

of

he

ad

s.

sp

ee

d o

f

20

mil

e/h

.

55

9

Mo

rr

is M

ini

He

ad

-o

n

coll

isio

n

Un

inj

ur

ed

. S

lig

ht

co

ncu

ssio

n,

196

4.

to

of

fs

ide

fro

nt

; N

o e

x-pl

ana

tio

n.

Ca

r.

es

tim

ate

d v

elo

ci

ty

cha

ng

e

20

-29

mil

e/h

.

69

7

Ren

au

lt

10

Ja

gua

r

swer

ved

r

ou

nd

Fa

cia

l l

ac

er

at

ion

s;

Co

ncu

ss

ion

; se

ve

re

19

6�

. a

pa

rk

ed

ca

r,

los

t b

ru

ise

d k

ne

es

. b

ruis

ing

. S

ea

t b

elt

J

ag

ua

r.

con

tro

l an

d h

it

fa

ile

d a

t t

op

a

nch

or

ag

e.

Ren

au

lt

he

ad

-o

n;

es

tim

ate

d v

elo

cit

y

cha

ng

e

20

-29

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