MOOSE-CAR ACCIDENTS Aspects on Injury Control
AKADEMISK AVHANDLING som med vederbörligt tillstånd av Rektorsämbetet vid Umeå universitet för avläggande av medicine doktorsexamen
kommer att offentligen försvaras
i Tandläkarhögskolans föreläsningssal B, 9 tr.
Regionsjukhuset, Umeå,
fredagen den 6 december 1985, kl 09.15
av Ulf Björnstig
Leg läkare
Umeå 1985
SNOWMOBILE, MOTORCYCLE AND MOOSE-CAR ACCIDENTS Aspects on In ju ry Control
Ulf Björnstig
Department of Surgery, University of Umeå, S-901 85 Umeå, Sweden
ABSTRACT
In ju r ie s related to snowmobiles, motorcycles and moose-car c ollis io n s have increased. The aim of the present thesis was to analyse mechanisms and consequences in fatal and non-fatal accidents of these types, and to penetrate possible preventive measures.
Snowmobiles
The median age of the injured was 30 and of the k i l l e d 32, males pre
dominating. A majority of the accidents occurred during weekends, and e specially the fatal accidents occurred a ft e r dark. The extrem ities were the most commonly injured parts of the body, however, drowning, crushed chest and cranial in ju rie s caused most of the f a t a l i t i e s . Among the f a t a l i t i e s , four out of five were under the influence of alcohol.
The present Swedish laws regarding snowmobiles seem well motivated.
" B u il t- in " safety measures in the construction of the snowmobiles, pro
perly designed snowmobile tracks and functional search and rescue sys
tems could reduce the in ju r ie s . Motorcycl es
The median age was 19 years for both the t r a f f i c injured and the k i l led. Half of the t r a f f i c accidents were c o llis io n s with other motor ve
h ic le s . In the f a t a l l y injured group, also c ollisio n s with fixed road
side objects were common. Of the f a t a l l y injured, more than every f i f t h person died in an accident where alcohol was an in f lu e n t ia l fa c to r. In the injured group, lower extremity in ju rie s (especially in off-road r id in g ) were common and among the f a t a l i t i e s most riders died from in ju r ie s to the head or chest. Out of one thousand motorcycle riders interviewed, 45% reported wobbling experiences (8% reported severe wobbling). Possible injury reducing measures include increasing the licensing age, more discriminating driving t e s t , " b u i l t - i n " re s t r ic tio n of the motorcycle's top speed, elimination of motorcycles prone to wobbling, and a more intensive t r a f f i c supervision (speeding, alco
hol ).
Moose-ca r c o1 l i si on s
The median age of the drivers was 38 years. Most c ollis io n s happened at dusk or when dark ( 3 / 4 ) . The median c o llis io n speed was 70 km/h. The damage to the car was t y p ic a l, the roof and the windshield p i l l a r s were deformed downwards and backwards. The broken windshield was often pressed into the passenger compartment. Most of the injured car occu
pants suffered cuts predominantly to the head and upper e xtrem ities.
Nearly a ll the f a t a l l y injured died of head and neck in ju r ie s . The i n ju r ie s may be reduced by strengthening the roof and the windshield p i l l a r s , and by introducing anti 1 acerati ve windshields.
Key words: I n j u r y , a c cid e n t, p reven tio n , snowmobile, motorcycle, moose- ca r c o l l i s i o n
From The Department of Surgery University of Umeå, Umeå, Sweden
SNOWMOBILE, MOTORCYCLE AND MOOSE-CAR ACCIDENTS
Aspects on Injury Control
by ULF BJÖRNSTIG
Y '
Umeå 1985
Johanna and Mattias
TABLE OF CONTENTS
ABSTRACT ... 7
ORIGINAL PAPERS ... 8
INTRODUCTION ... 9
Injury control and Haddon's matrix ... 10
AIMS OF THE THESIS ... 13
SNOWMOBILE RELATED INJURIES Materials and Methods ... 15
Results ... 16
Discussion ... 19
MOTORCYC.E RELATED INJURIES D efinitions ... 27
Material and Methods ... 27
Results ... 29
Discussion ... 36
INJURIES RELATED TO MOOSE-CAR COLLISIONS D efin itio ns ... 47
Materials and Methods ... 47
Results ... 49
Discussion ... 52
FINAL CONCLUSIONS ... 59
REFERENCES ... 60
ACKNOWLEDGEMENTS ... 64 Paper I ...
Paper I I ...
Paper I I I ...
Paper IV ...
Paper V ...
Paper VI ...
Paper V II ...
Paper V I I I ...
ABSTRACT
In ju rie s related to snowmobiles, motorcycles and mooso-car c ollisio n s have increased. The aim of the present thesis was to analyse mechanisms and consequences in fa ta l and non-fatal accidents of these types, and to penetrate possible preventive measures.
Snowmobile s
The median age of the injured was 30 and of the k i l l e d 32, males pre
dominating. A majority of the accidents occurred during weekends, and especially the fatal accidents occurred a f t e r dark. The extremities were the most commonly injured parts of the body, however, drowning, crushed chest and cranial in ju rie s caused most of the f a t a l i t i e s . Among the f a t a l i t i e s , four out of fiv e were under the influence of alcohol.
The present Swedish laws regarding snowmobiles seem well motivated.
" B u ilt- in " safety measures in the construction of the snowmobiles, pro
perly designed snowmobile tracks and functional search and rescue sys
tems could reduce the in ju r i e s . Motorcycles
The median age was 19 years for both the t r a f f i c injured and the k i l le d. Half of the t r a f f i c accidents were collisions with other motor ve
h ic les . In the f a t a l l y injured group, also collisions with fixed road
side objects were common. Of the f a t a l l y injured, more than every f i f t h person died in an accident where alcohol was an in f lu e n t ia l facto r. In the injured group, lower extremity in ju rie s (esp ecially in off-road r id in g ) were common and among the f a t a l i t i e s most riders died from in ju r ie s to the head or chest. Out of one thousand motorcycle riders interviewed, 45% reported wobbling experiences (8% reported severe wobbling). Possible injury reducing measures include increasing the licensing age, more discriminating driving t e s t, " b u i l t - i n " r e s tr ic tio n of the motorcycle's top speed, elimination of motorcycles prone to wobbling, and a more intensive t r a f f i c supervision (speeding, alco
h o l).
Moose-car c o llis io n s
The median age of the drivers was 38 years. Most c ollisio n s happened at dusk or when dark ( 3 / 4 ) . The median c o llis io n speed was 70 km/h. The damage to the car was t y p ic a l, the roof and the windshield p i l l a r s were deformed downwards and backwards. The broken windshield was often pressed into the passenger compartment. Most of the injured car occu
pants suffered cuts predominantly to the head and upper e xtrem ities.
Nearly a ll the f a t a l l y injured died of head and neck in ju r i e s . The in ju r ie s may be reduced by strengthening the roof and the windshield p i l l a r s , and by introducing a n t i l acerati ve windshields.
Key words: I n j u r y , acc id e n t, preven tio n , snowmobile, motorcycle, moose- car c o l l i s i o n
ORIGINAL PAPERS
This thesis is based on the following publications, which w il l be re
ferred to by t h e ir Roman numerals:
SNOWMOBILE RELATED INJURIES
I Björnstig U, Eriksson A, Mellbring G.
Snowmobiling in ju rie s : types and consequences.
Acta Chirurgica Scandinavica 1984;150:619-624.
I I Eriksson A, Björnstig U.
Fatal snowmobile accidents in northern Sweden.
Journal of Trauma 1982;22:977-982.
MOTORCYCLE RELATED INJURIES I I I Björnstig U, Bylund P-0.
Motorcycling in ju rie s in northern Sweden. On-road and off-road rid in g .
Travel Medicine In te rn a tio n a l. In press 1985.
IY Björnstig U, Bylund P-0, Lekander T, Brorson B.
Motorcycle f a t a l i t i e s in Sweden.
Acta Chirurgica Scandinavica. In press 1985.
Y Björnstig U, Bylund P-0.
Wobbling motorcycles cause serious in ju rie s and f a t a l i t i e s . Travel and T r a f f i c Medicine International 1983;1:153-157.
VI Brorsson B, If v e r J, Björnstig U.
Wobbling in modern motorcycles.
Accident Analysis & Prevention 1984;16:451-456.
INJURIES RELATED TO MOOSE-CAR COLLISIONS
V II Björnstig U, Bylund P-0, Eriksson A, Thorson J.
Moose-car c o llis io n s . Mechanisms and inju ry preventive stra te g ie s.
Manuscript. Shortened version in press in American Journal of Pub
l i c Health 1985.
V I I I Eriksson A, Björnstig U, Thorson J.
Collis ions between cars and mooses. An analysis of c o llis io n s with f a ta l personal in ju r ie s .
Travel Medicine In ternational 1985;3:130-137.
INTRODUCTION
T r a f f ic in ju rie s have during the la s t decades received increasing attention from researchers. Despite an increase in t r a f f i c a c t i v i t y , the total number of people k i l l e d in t r a f f i c has decreased during the seventies in Sweden (Fig. 1 ). A s im ila r trend has also been observed in other countries, e.g. in the USA where the f a t a l i t y rate has decreased as i l l u s t r a t e d in Fig. 2.
Fig. 1.
Road t r a f f i c accidents re
ported by the police and to ta l t r a f f i c a c t i v i t y , 1970-1982. Non b u ilt-u p areas. Index 1970 = 100.
t = t r a f f i c a c t i v i t y , i - accidents with personal in ju ry , f = fa t a l acci
dents ( 1 ) . / \
1970 1973 1976 1979 19821
5
1960 1970 1980
Fig . 2.
US t r a f f i c f a t a l i t y rate (n) per year and 100 m il
lio n of vehicle miles t r a veled ( 2 ).
Factors influencing this positiv e trend are reduced speed li m i t s , seat belts and helmets and increasing demands on the cars, where the US standard (FMYSS = Federal Motor Vehicle Safety Standards) in many cases have been a guideline for other countries. The intention of these stan
dards is to reduce the frequency of accidents ( e .g . standards for mir
ro rs, lig h t s and tyres) and the likelih o o d of in ju ries sustained (e.g.
standards for windshields and steering assembly). The extent of damage
beeing exaggerated by e.g. a postcrash f i r e should also be reduced by those standards. In the USA i t is estimated that vehicle standards introduced have saved more than ?5 000 liv e s between 1066 - 1974 ( 3 ) .
However, in ju rie s caused by certain accidents such as accidents in v ol
ving snowmobiles and motorcycles have shown a tendency to increase, as have c ollis io n s between cars and animals (Fig. 3 ) , mostly moose ( 4 - 6 ) . Several factors may have contributed to this trend: t technical deve
lopment and fashion trends have made snowmobiles and motorcycles more popular with a consequent increase in the number of these vehicles.
Further, the number of moose increased during the seventies in Sweden, also increasing the risk of c o llis io n s with moose.
Fig. 3.
Number of road t r a f f i c accidents between motor vehicles and animals in Sweden. Accidents in v o l
ving in ju ry to person ( 6 ) . About 90% of these acci
dents involved a moose or a roe-deer.
INJURY CONTROL AND HADDON'S MATRIX (7, 8)
The word "injury" (in + ju s, "not rig h t " ) means harm, hurt, loss or wrong. The term usually refers to damage re sultin g from acute exposure to physical or chemical agents. In the present thesis, the most impor
tant e tio lo g ic al agent is mechanical energy, carried by a v eh ic le (e.g . snowmobile, motorcycle or c a r ). The in ju ries are caused by unwanted energy transfer to the human body.
The fundamental tasks in inju ry control are to:
- prevent the agents (here mechanical energy) from reaching people in amounts that exceed injury thresholds,
- minimize the consequences of in ju ries when in e v ita b le . 500
O L -
1970 1980
In ju ry control could be aimed at the agent, at reducing exposure or human s u s c e p tib ility .
Haddon's matrix (Table I ) was considered a suitable method for the ana
ly s is of the events that the present thesis deals w ith. Haddon's analy
t i c framework (7 , 8) divides the sequence of events into three phases:
pre-crash, crash and post-crash. In each of these phases human, vehicle and environmental factors operate and determine the outcome. The end re s u lt is damage to people, v eh ic le, equipment, physical environment and society. The aim is to manipulate these factors in such a way that human injury is avoided, minimized or successfully treate d.
The f i r s t (pre-crash) phase includes a ll factors that influence upon the likelihood of an accident taking place. In the second (crash- phase), counter-measures attempt to prevent harmful interaction of the e tio lo g ic a l agent (here mechanical energy) with the host. Even i f the crash is not prevented, the varie ty and effectiveness of the counter
measures at this level determine whether the in ju rie s to the human can be avoided or minimized. The th ird (post-crash) phase refers to maxi
mizing salvage, once damage has been done, keeping death and d is a b ili t y to a mimi num.
Approaches to the inju ry problem are not lim ited to primary prevention of the i n i t i a l event, but involve any stage of the injury-producing process that can be e ff e c t i v e ly changed. P r io r it y should be given to measures that w ill most e f f e c t i v e ly reduce injury and the choice should not be determined by the r e la t iv e importance of causal or contributing factors only, or by t h e ir order in the sequence of events. As a re su lt of f a i l u r e to understand this poin t, emphasis on "human error" as the cause of most in ju r i e s , has resulted in undue emphasis on changing behaviour, rather than on using more e ff e c tiv e measures to reduce in j u r i e s . A mixed strategy should usually be employed, incorporating countermeasures addressed to the three phases: pre-crash, crash and post-crash. Preference should, i f possible, be given to "passive" or
"automatic" measures, i . e . those that protect the individual automa
t i c a l l y without any action on his part (9, 10). The aim should be that neither mechanical f a i l u r e , nor human action should re su lt in personal in ju ry .
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OF mJTHESJiS
The aim of the present thesis was to analyse snowmobile, motorcycle and moose-car accidents and:
- to describe inju ry mechanisms and consequences in non-fatal and fa ta l accidents,
- to analyse the wobbling experience of owners of modern motorcycles, - to suggest possible injury-preventive measures.
SNOWMOBILE RELATED INJURIES ( I , I I )
Fig. 4. Swedish law stipula tes that a snowmobile must be registered and insured. A snowmobile may not be driven along public roads, within certain recreational areas, densely b u ilt-u p areas or w ithin nature reserves. The T r a f f i c Temperance Law applies to drivers of these vehicles and the d river must be at least 16 years old. Further, by voluntary agreement, organized import is r e s tr ic te d to snowmobiles with a maximum e ff e c t of 60 hp,* how
ever these can reach top speeds of 160 - 180 km/h.
MATERIAL AND METHODS
Paper I
People injured in snowmobile accidents during the winter (Nov.-May) 1979-1980, (n = 137), were interviewed when seeking medical attentio n a t hospitals or d i s t r i c t medical o ffic e r s in the county of Västerbot
ten. A to ta l of 137 injured snowmobilers were registered (Series I ) . The doctors were requested in repeated personal communications to pay special attentio n to any involvement of alcohol in the accidents. Case records and Social Security O ffice documents were analysed.
* 1 horsepower (hp) = 0,74 kW
According to the Swedish Meteorological and Hydrological In s t i t u t e (1 1 ) , the f i r s t snow came 1n the Inland parts of the area 1n la te October. No In ju rie s were reported u n til November when snow was also present in the coastal areas.
The best available estimation of the speed at the moment of the acci
dent was the statements of the speed given by the Injured persons them
selves 1n the Interviews.
The In ju rie s were graded according to the Abbreviated In ju ry Scale (AIS) where MAIS denotes Maximum AIS (1 2 ). AIS = 1 is a minor In ju ry;
AIS = 2 is a moderat in ju ry as e.g. a concussion or an uncomplicated fra c tu re ; AIS = 6 is an in stant fa t a l in ju ry . The mean MAIS-value was calculated in some cases, this simply denotes the mean value of the d i f f e r e n t MAIS-values in the group and should not be regarded as the severity of a "mean in ju ry ".
Paper I I
All f a t a l i t i e s (n = 36) in the four most northern counties in Sweden during eight seasons (1973-07-01 - - 1981-07-01) were analysed (Series I I ) . This area is h a lf the tota l area of Sweden and in this area there was one snowmobile in t r a f f i c per 15 inhabitants in 1980. Registration of snowmobiles has been compulsory in Sweden since 1974.
RESULTS
The results are presented in detail in Papers I and I I . A summary of the results and some additional results are presented here.
In ju ry incidence and f a t a l i t y rate
The number of snowmobiles in t r a f f i c in the county of Västerbotten was 15 000 or 24% of the to ta l number of a l l registered snowmobiles in Sweden (1980-01-01). There were 230 000 inhabitants in the county, i . e . there was 1 registered snowmobile per 15 inhabita nts .
The in ju ry incidence was 9 per 1 000 snowmobiles and the f a t a l i t y rate about 1 per 10 000 snowmobiles. Assuming an annual driving distance per
vehicle of about 1 000 km (cf 13, I) this gives 100 injured and 1 k i l led per 10 m illio n kilometres.
Age, sex and d r i v i n g _experience
Men between 20-39 years (median age 30 and 32, respectively) were in jured most frequently in both series I and I I and constituted 44% and 53% (n = 19), respectively. Drivers were injured and k i lle d more f r e quently (67%; I and 83% (n = 30); I I ) , than passengers. Of 117 drivers with a known annual driving distance in series I , 21% stated that they were beginners ( i . e . with a total driving distance <100 km). Among the f a t a l l y injured drivers 10% (n = 3) were considered to be beginners according to the police in vestigatio ns.
Time of accident
During the months of March and A p r i l , 45% ( I ) were injured and 42%
(n = 15) ( I I ) were k i l l e d . During November and December, when the ice is usually th in , 33% (n = 12) were k i l l e d (9 drownings) compared with only 18% injured in series I . Most people were injured during weekends and holidays in both series, 65% ( I ) and 56% (n = 20) ( I I ) . In series I only 18% of the riders were injured between 06.00 p.m. - 06.00 a.m., but 69% (n = 25) of the f a t a l i t i e s were injured during these darker hours.
The accident
The most frequent mechanism of injury (50% in series I ) were: a sudden stop due to a c o llis io n with a fixed object, driving into a ditch and the l i k e , or f a l l i n g o ff the machine for other reasons. Six of the ten who were injured at high speed ( >80 km/h) ( I ) had fa lle n o ff the machine because of high speed on uneven t e r r a in . Among the f a t a l i t i e s , driv ing through thin ice was the most frequent accident mechanism which caused 42% (n = 15) of the f a t a l i t i e s . A sudden stop was the cause in 33% (n = 12) of the f a t a l i t i e s and three had collided with a moving car. I t was obvious from the police investigations that the speed had been high in these l a t t e r accidents. Two riders had been strangled when parts of clothing had got caught in the rotatin g parts of the motor and one oerson had been k i l l e d when his snowmobile overturned and f e l l on top of him. These two l a t t e r types of accidents were not represented in
series I . In series I , 6% were injured because of other mechanical f a u lt s such a jammed t h r o t t l e , broken suspension or d isin tegratio n of the running board or wheel.
The in ju rie s and helmet usage
In series I almost half of the injured suffered MAIS > 2 in ju r i e s . Three out of the ten persons injured at a speed stated to be 80 km/h or higher, had serious in ju rie s (MAIS > 3 ) and the mean MAIS-value was 2.1 for this group compared with 1.6 for those injured at lower speeds. In series I , the lower extremities were most commonly injured (35%) f o l lowed by the upper extremities (25%) and head and neck (17%). Among the f a t a l i t i e s , drowning was the most frequent cause of death, 39% (n = 14). Crushed chest caused the death in 31% (n = 11) of the cases and in trac ra n ial in ju rie s in 17% (n = 6 ). Suffocation and intraabdominal in ju r ie s caused the remaining f a t a l i t i e s .
Helmets were worn by 50% of the riders in series I . Helmet usage was only 16% (3 of 19) in the age groups over 50. Of the f a t a l i t i e s 31%
n - 11) were helmeted.
Treatment and sickness benefit
A total of 28% of the injured in series I were treated as in -p atien ts for a total of 411 days, i . e . on average 11 days per person. The age group 30-39 had the highest number of in -p a tie n t treatment days or 170 days which was 41% of a ll in -p a tie n t treatment days (Fig . 5, Paper I ) . Among the f a t a l i t i e s 89% (n = 32) died before a rriv a l at the hospital and the remaining four persons liv ed 1-3 days a ft e r the accident.
Sickness insurance benefit was paid to 64% of the injured for an average of 48 days (mean SEK 5 8 0 0 /e n title d person). The total "cost"
of treatment and sickness allowance was SEK 1.1 m illio n in 1979 years monetary value or SEK 8 200 per in jured. For the whole country this would be around SEK 4 - 5 m illio n annually ( I ) .
Alcohol
Among the injured ( 1 ) 6 out of 80 (8%) seeking medical attention within 24 hours, were obviously (or stated by themselves) under the influence of alcohol. All 6 were men between 20-49 years of age, 3 collided with
an obstacle and 2 had fa lle n o f f the vehicle when driv in g. Three of those received in -p a tie n t treatment for 32 days, which on average is the same treatment time as for the other in -p atien ts treated. However, these 6 were on sick leave for a total of 576 days or 96 days per per
son, which is twice as long as the average leave (45 days) of the other injured persons. The mean cost per injured for these six was SEK 28 000 compared with SEK 7 300 for the other group.
Among the f a t a l i t i e s , post-mortems were carried out in a ll 36 cases.
Drunken driving could be excluded in only 17% (n = 6) of the cases and the mean blood alcohol level was 1.6 g/1 in 23 cases who died imme
d ia te ly and in which postmortem alcohol analyses was performed. Four
teen of 20 microscopic analysed liv e r s exhibited l i v e r steatosis and/or c irrh o sis consistent with alcohol abuse.
DISCUSSION
The discussion is systematized according to Haddon's matrix. The fac
tors discussed are summarized in Table I I (p. 26). Each cell is dis
cussed separately.
Precrash-human c ell
Against the background of the enormous speed potential of the fastest snowmobiles (180 km/h) the Swedish age l i m i t of 16 years can be con
ceived to be too low. In the present study, there were, however, no f a t a l i t i e s among drivers below 20 years of age and neither were the freguency of in ju r ie s especially high, the average in -p a tie n t treatment time was not s ig n i fi c a n t ly longer e ith e r . These findings therefore do not indicate that the 16-year age l i m i t is too low from the injury point of view. However, the exposure may be small among the youngest drivers.
Every f i f t h person injured ( I ) and every tenth person deceased ( I I ) had only minor driving experience. Perhaps a b etter and more extensive tra in in g could have prevented some of these in ju r ie s . Today only volun
tary tra in in g in snowmobile clubs is available and the educational
value is d i f f i c u l t to assess (c f 1 4). However, this tra in in g is pro
bably b e tte r than no tra in in g at a ll and an important educational goal fo r the clubs should be to discourage dangerous d riv in g . Licensing as a p re req u is ite to re g is te r a person as owner of a snowmobile could be di scussed.
Among the f a t a l i t i e s , drunken drivin g was an important factor and the figures of blood alcohol levels were d istu rb in g ly high. In series I only about 8% were considered as obviously being under the influence of alcohol. The f a t a l it i e s often happened a fte r dark on a weekend; this being consistant with what is known from other vehicle accidents with fa ta l outcome (1 5 -1 7 ). However, the percentage of intoxicated snow- mobilers (83%) seems higher than corresponding figures for other vehic
le s . In a study of fa ta l single car accidents also from the northern p art of Sweden, 56% o f the drivers were reported to have been driving under the influence of alcohol (18) and in another study from the southern part of Sweden Krantz found th is to be the case in 50% (1 7 ).
In our study on motorcycle f a t a l it i e s (IV ) alcohol was an in flu e n tia l fa c to r in 23% o f the f a t a l i t i e s . Perhaps the risks involved in driving a snowmobile when drunk are underestimated and the fa c t th a t the T ra f
f ic Temperance Law also applies to snowmobilers is a fac t that is not common knowledge. I t is obvious th a t the a b ilit y to drive a snowmobile is impaired when in e b riate d . I f other solutions to the transportation problem of in ebriated persons are possible, e .g . by organized group transports from p a rtie s , or by help from a frie n d or other person, this would be b en eficial from the in ju ry point of view.
Despite the re la tiv e ly low age of the deceased, more than 1 out of 5 were known alcohol abusers and many of the m icroscopically examined liv e r s exhibited steatosis and/or cirrh o sis consistent with alcohol abuse. At le as t three of the f a t a lly injured drivers had e a r lie r lo st th e ir car driving licence and one person had lo s t his f ir e arm licence because of alcohol abuse ( I I ) . This indicates th at at le as t among the deceased a deviant personality may be overrepresented. Krantz (17) found that more than 50% of car drivers involved in fa ta l single ve
h ic le accidents were known to the a u th o ritie s (reg is tere d in criminal or social records). Waller and Lamborn (19) characterized injured snow
mobilers as e ith e r young inexperienced d riv e rs , or o ld er, aggressive
men who had a high alcohol intake and with more snowmobile accidents and t r a f f i c v io latio n s than other d riv ers . They also found that in most cases where the speed a t the time of the accident was over 50 km/h the snowmobile d riv e r was in to xicated .
Crash-human c e ll
The way bodies move in a crash can be an important fa c to r, e.g . a c h ild s itt in g in fro n t of an adult could be crushed by the forward movement o f the l a t t e r , esp ecially i f c o llid in g with a road b a rrie r or other immovable o b ject. I t would be wise to place children behind the d riv e r.
Perhaps a rid e r can minimize the impact forces in certain situations i f he can jump o ff the machine p rio r to impact. The older victims had a longer mean stay in hospital and more days o ff work than the younger ones ( I ) ; th is being typ ical fo r the e ld e rly who are well known to display greater v u ln e r a b ilit y and have a slower recovery. Thus, e ld e rly persons ought to temper th e ir snowmobiling a c t iv itie s as they do with other p o te n tia lly dangerous sports.
Postcrash-human c e ll
Knowledge of f i r s t aid among snowmobile rid ers and other persons in v o l
ved in a crash can determine the outcome. By using snowmobile tracks and by avoiding to drive alone, the chances of being helped quickly are increased. The importance of these factors may be illu s tr a te d by two of the f a t a l i t i e s : one person got caught under his overturned snowmobile and died of suffocation by imm obilization of the chest, another person, unconscious but not le th a l ly in ju re d , drowned in 15 cm deep water. I t is essential th a t rescue a c t iv itie s are triggered as soon as possible.
The risk of making the in ju rie s even worse, and to receive additional fro s t or hypothermic in ju r ie s , increases i f the weather is windy and cold (2 0 ). Food, warm drinks and warm and dry clothes would keep the in ju red warm. Influence of alcohol can also be a postcrash problem and in th is s itu a tio n make the injured more prone to misjudge the in ju rie s and the proper handling of them.
P recrash-vehicle and equipment c e ll
Faults with the snowmobile i t s e l f were seldom the cause of the acci
dents ( I , I I ) . Of course, a ll ro ta tin g engine parts should be e ffe c t iv e ly covered to prevent g ettin g parts of clothing caught in e.g. the
f ly wheel (21, 22, I I ) . I t is more d i f f i c u l t to elim inate the risk of g ettin g parts of clothing caught in the running board. A fte r the com
p le tio n o f paper I I one person was k ille d when his anorak got caught in the running board when he trie d to l i f t a stuck snowmobile. A "dead mans grip" and information about these risks would be b e n e fic ia l.
D e fic ie n t handling of snowmobiles has not been claimed as an accident cause. Perhaps a fu rth e r improvement of the steering skis and suspen
sion would decrease the risk of a sudden stop and of receiving in ju rie s to the spine when driving on rough t e r r a in . I t could also be questioned i f the snowmobile lig h tin g had been s a tis fa c to ry in some cases as the rid e r co llid ed with a road b a rrie r in the dark.
The statements of the speed at the accidents are of lim ite d accurracy, however, i t was obvious th a t some of the accidents had happened at high speed ( I , I I ) . I t could be questioned whether a snowmobile should have such an impressive speed potential as is the case at present. A l i m i t ation of the engine size or power output could be discussed, lik e an automatic lim ita tio n of the maximum number of revolutions. The d is advantage of some of these lim ita tio n s is that i t is r e la tiv e ly easy to override them.
Crash-vehicle and equipment c e ll
In a crash the riders could be injured by sharp, hard and prominent parts of the snowmobile or get th e ir fe e t and lower legs caught and tw isted between the snowmobile and the ground. The construction of modern snowmobiles seems, however, often to be quite good from this point of view. This opinion is supported by our re s u lts : in our series ( I ) 35% o f the in ju rie s were lower extrem ity in ju rie s which could be compared with corresponding figures (45-56%) reported in several stu
dies from the USA and Canada a decade ago (2 2 -2 6 ). Three persons were injured when th e ir chin h it the area around the centre of the handlebar when the snowmobile suddenly stopped. Padding (softening) of the parts most lik e ly to be h it by the rid e r would reduce the risk of in ju ry .
F urther, a strengthening of the construction of the fro ntal part and windshield of the snowmobile could influence the severity of in ju rie s caused by c o llis io n s with e .g . road b arriers (3 f a t a l it i e s ( I I ) ) or un-
