Motorcycle Accidents and A Icohol Use

Transcription

1 Motorcycle Accidents and A Icohol Use Martin Williams3 b REPORTS OF ALCOHOL USE IN MOTORCYCLE ACCIDENTS The reported role of alcohol use in motorcycle accidents appears to be a function of the m ethods used to detect its presence. In three studies its role is reported to be of little consequence. Raeder and Negri6 found that only sixty-nine of the 7982 motorcycle operators involved in fatal and personal injury motorcyle accidents in New York State in 1966 and 1967 were reported to have been drinking alcoholic beverages prior to the accident. This num ber represented 0.9% of the total number o f motorcycle operators. The writers acknowledged that this figure was very low compared to other findings but they offered no explanation for the result. Berenguel, 1 investigated 121 fatal motorcycle accidents which occurred in Iowa from In 7% of the eightyfour multi-vehicle accidents the motorist had been drinking, but there was no indication of the num ber of drinking riders involved in these accidents. In 11% of the thirty-seven single vehicle accidents the rider had been drinking. Jamieson and Tait4 found that 16% of riders involved in 103 injury producing motorcyle accidents were under the influence of alcohol. In none o f these reports were the alcohol levels quantified. Presumably this meant that detection was dependent on police reporting rather than on clinical measurement. A very different result arises when post-mortem examinations are performed on large samples of fatally injured motorcycle riders. M arsden,5 reporting on the deaths of eighty-two motorcycle riders killed in San Diego from January 1970 to July 1972, found that 31% of the riders had measurable amounts of alcohol in their blood ; 84% of the readings were above 0.05 gm100 ml and 64% were in excess of 0.10 gm100 ml. G raham 2 reported blood alcohol levels measured in 352 motorcycle riders andor pillion passengers killed in Los Angeles County in the five year period from O f the 193 operators who survived less than six hours, 46% had measurable blood alcohol, while 35% of the readings were greater than 0.10 gm100 ml. Sm ith13 reported the results of post-mortem blood alcohol tests performed on motorcycle riders fatally injured in Perth, W.A., from Thirty-six per cent o f the 173 riders tested showed positive alcohol. The W estern Australian G overnment Chemical Laboratories15,16 reported blood alcohol levels found in motorcycle riders killed in Western Australia. In 1973, 21% of the nineteen riders tested had a blood alcohol level above 0.05 gm100 ml. In % of forty-three riders tested for alcohol had a blood alcohol level above 0.05 gm100 ml; 84% of the recorded levels were in excess of 0.10 g m 100 ml. No reason was given for the difference in these figures and none was apparent in the papers. Seventy-nine per cent of the motorcycle riders killed in Western Australia in 1973 were tested for blood alcohol, yet only 67% were tested in Tonge14 provided details of blood alcohol level found in ninety-four motorcycle riders killed in Brisbane from July 1955 to June Thirty-four per cent of the killed riders had a blood alcohol levels above 0.05 gm100 ml and 79% of the recorded blood alcohol levels were in excess ofo.lo gm100 ml. a Department o f Mechanical Engineering, University of Melbourne bthis work was performed as part of a study of Motorcycle Visibility sponsored by the Commonwealth Department of Transport. The views expressed are those of the author and not necessarily those of the Department of Transport. 38

2 Motorcycle Accidents and Alcohol Use 39 The one available report of post-mortem examinations which indicated a low level of alcohol use amongst motorcyle riders was that of Hossack and Brown.3 They found that only 17% of fifty-two motorcycle riders tested in Victoria from January 1972 to July 1973 had ingested alcohol and that 78% of the recorded blood alcohol levels were in excess of 0.10 gm ml. These reports indicate that when the presence of alcohol in riders is clinically measured it is found to have influenced large proportions of fatal motorcyle accidents. No conclusion can be drawn from the literature about the role of alcohol in injury producing accidents because previously no reliable method had existed to detect its presence in all motor accident victims. The present study of Victorian motorcycle accidents had two aims: to obtain data on fatal accidents for comparison with previous work, and to determine the importance of alcohol in injury-producing accidents. O f the 1577 casualty accidents reported to police in were studied to obtain this inform ation. ALCOHOL USE IN MOTORCYCLE ACCIDENTS IN VICTORIA DURING 1974 Introduction In early April 1974 legislation became effective in the State of Victoria which made it com pulsory for any person who was adm itted to the Casualty W ard of a hospital to furnish blood for testing. One sample was retained at the hospital for the patients use, one was held for the Victorian police and a third was sent to the Coroners C ourt for clinical analysis. This change in legislation did not guarantee that a record of blood alcohol found in a motorcycle rider would reach the relevant police file. Naturally the main interest of the police was to determine whether a rider involved in an accident (few car drivers involved in any of the 1508 accidents studied were sufficiently injured to warrant hospital attention) had consumed more than the legal limit of alcohol. This was determined in either of two ways. If the Coroners Court analysis showed positive alcohol or if the police suspected alcohol use, the police sample was tested for blood alcohol. This method resulted in a good cover of the accidents likely to have involved alcohol use but it did not indicate the proportion of injured riders who were tested for alcohol, or the num ber who were tested and found to have no alcohol in their blood. The data are incomplete. They do not reveal the full picture of alcohol use in motorcycle accidents in the period studied but they provide a lower limit to the extent of its use. Extent of Use Alcohol was present in at least 12% of the 1508 fatal and injury producing motorcycle accidents which were studied. O f these, the rider alone had been drinking in 74% of the cases; the other driver in 17%; a pedestrian in 4%; while both the rider and driver were affected in 5%. The figures for alcohol use amongst riders should give an accurate representation of its role in that group of road users. However, the law which ensured that injured persons who were hospitalised after a motorcycle accident were tested for blood alcohol automatically would have biased the detection rate towards the riders. They were almost invariably injured in accidents while the injury rate amongst the drivers who collided with them was insignificant. There was no established mechanism for testing the blood alcohol levels of these uninjured drivers - detection depended on police breathalyser tests. Consequently, the use of alcohol in this group o f drivers has probably been understated.

3 40 M. Williams This was indicated by the fact that 39% of the drivers who were said to have been drinking were not tested for alcohol, while the equivalent figure for motorcycle riders was 19%. Characteristics o f Accidents in which Alcohol Use was Detected Severity o f Accidents. Although alcohol use was detected in 12% of all the motorcycle accidents it was present in 41% o f the seventy-six reported fatal accidents. In 71% of the fatal accidents the rider alone had been drinking. The other driver only was affected by alcohol in 16%, while both the rider and driver were affected in 13% of cases. A chi-square test o f accident severity (injuryfatal) for alcohol and non-alcohol involved riders (Table I), shows an over-representation o f alcohol affected riders in fatal accidents. TABLE I Severity o f injuries fo r alcohol and non-alcohol affected accidentsa Non-alcohol Alcohol Injury (1265.8) (163.3) Fatal (67.2) (8.7) ( X.2 = 65.36, df = 1, p <.001) a Numbers in brackets are expected frequencies. Type o f Accident. Alcohol was more likely to be present in riders involved in single vehicle rather than multi-vehicle accidents (Table II). It is seen that the group of alcohol affected riders is significantly over-represented in single vehicle accidents. While 17% o f the 1508 motorcycle accidents were single vehicle, 38% of the alcohol affected accidents and 52% o f the fatal accidents which involved alcohol were single vehicle. TABLE II Type o f accident (multi-single vehicle) fo r alcohol and non-alcohol affected groups o f riders'0 Non-alcohol Alcohol Multi (1106.7) (145.3) Single (226.3) (29.7) ( X.2 = 55.52, d f= 1, p <.001) b Numbers in brackets are expected frequencies. Age o f Accident Victim and Level o f Alcohol Driver. O f the 43 drivers who were suspected of having used alcohol prior to an accident, 63% were less than 25 years of age (Figure 1). O f the 30 recorded blood alcohol levels 90% were in excess o f 0.05 g m 100 ml (Figure 2). The difference in the sample numbers resulted from the fact that thirteen drivers who were said to have been drinking were not tested for alcohol. It is difficult to draw conclusions from these data because the sample is small.

4 Motorcycle Accidents and Alcohol Use 41 PERCENT 30 % i i Figure 1 Age o f drivers affected by alcohol (n = 43). 20 % B.A.C. (gm 100m l) Figure 2 Blood alcohol concentration o f drivers (n = 30). Pedestrian. In the seven accidents which involved a pedestrian, alcohol use by the rider was suspected in three cases and by the pedestrian in four. All four of these pedestrians were elderly and were struck close to a hotel at night. All were reported to have been drinking heavily, but no blood alcohol levels were available.

5 42 M. Williams Once again no valid conclusion can be drawn about these accidents because of their rarity. Riders. The majority of the 113 injured riders who were said to have been drinking alcohol were in the age group from years (83%) (Figure 3). 86% of the ninety-three recorded blood alcohol levels were greater than 0.05 gm ml, while 35% were above 0.15 gm100 ml (Figure 4). Figure 3 Ages o f killed and injured motorcycle riders affected by alcohol. Similar figures were obtained for the fatal motorcycle accidents: 88% of the twenty-four riders suspected of having used alcohol were aged from years; 94% of the eighteen recorded blood alcohol levels were in excess of 0.05 gm100 ml; 61% of the levels were above 0.15 gm100 ml (Figures 3 and 4). The very strong effect o f age on motorcycle accidents which involved alcohol use is in contrast with the situation for car drivers. (86% o f the riders were younger than 25 years o f age). R obertson10 found that for a group of breathalysed drivers, only 35% were below the age of 25 years. To some extent this difference might be accounted for by the fact that motorcycle riding is a youthful occupation. Figures obtained from the Victorian Road Safety and Traffic A uthority substantiate this assertion. The age distribution of all 137 alcohol affected riders is similar to that for 1268 of the riders involved in casualty accidents in Victoria in 1974 (Figure 5). The figures for blood alcohol levels are disturbing, particularly in view o f the youthfulness of the motorcycle riders involved. O f all recorded blood alcohol levels 78% were greater than the legal limit in Victoria (0.05 gm100 ml) and 40% were greater than 0.15 gm100 ml. Blood alcohol levels in excess of 0.15 gm100 ml are usually obtained as a result of sustained heavy drinking. Investigations by Rankin,7 Raym ond8 and Santam aria12 indicated that a person who is found to have a blood alcohol concentration of this level is likely to have a drinking problem. Furtherm ore, the person usually drinks enough alcohol to maintain a constant level of 0.05 gm100 ml throughout most of his working and driving hours.

6 Motorcycle Accidents and Alcohol Use 43 % _ PERCENT! PH * INJURY ( n = 93 ) 0 FATAL(n=18) 20 _ 10 I I \ V I FI a B.A.C. I gm 100 ml) Figure 4 B lood alcohol concentration o f k ille d and injured m otorcycle riders. 60. PERCENT [ ] DRINKING RiOERS ( n = 137) % ; 2 71 YX KILLED & INJURED RIDERS ( n =1268 ) Z! 171 i F7I \ I I I I 33 + AGE Figures 5 Comparison o f ages o f 137 drinking riders and 1268 killed and injured riders.

7 44 M. Williams ALCOHOL USE IN FATAL MOTORCYCLE ACCIDENTS IN AUSTRALIA AN ANALYSIS OF SIX STUDIES Number o f Accidents Affected by Alcohol Use Blood alcohol tests taken during post-mortem examinations of motorcycle riders have been reported by Smith, 13 Western Australian Governm ent Chemical Laboratories, Tonge, 14 Hossack and Brown3 (Table III). Approximately 1096 riders were killed in the various regions during the relevant periods. O f these riders 39% were tested for the presence of blood alcohol and a non-zero reading was obtained in 35% o f the cases. TABLE III Detection o f alcohol use amongst 426 killed riders Riders Riders Testing PositiveA Icohol Study Place Period killed (n) tested (n) rate (%) n % Smith Perth, approx. 173 approx. (undated) W.A W.A.G.C.L. W.A (1973) W.A.G.C.L. W.A (1974) Tonge, Brisbane approx. 94 approx (1972) Hossack, et al. Vic (1974) This study Vic approx. approx. TOTALS % % Blood Alcohol Levels Details of blood alcohol levels found in killed riders are shown in Table IV. Data was obtained from 5 studies, including W.A.G.C.L.,15-16 Tonge, 14 Hossack and Brown3 and this study. TABLE IV Blood alcohol levels found in 253 killed motorcycle riders Blood Alcohol Concentration (gm 100 ml) STU D Y.000 to.050 to.100 to.150 to.200 to.250 to Sum NIL W.A.G.C.L. (1973) W.A.G.C.L. (1974) Tonge, (1972) Hossack, et al. (1974) This study Total The combined figures for the five Australian States are shown in Figure 6. The blood alcohol levels attained by the killed riders who were affected by alcohol were remarkably high. Ninety-two per cent were above 0.05 gm100 ml, but the majority (53%) were in excess o f 0.15 gm100 ml. The majority o f killed motorcycle riders had blood alcohol levels typical of problem drinkers.

8 Motorcycle Accidents and Alcohol Use 45 UO r. PERCENT KILLED RIDERS (n = 87) 30 % _L B.A.C. (gm100 ml ) Figure 6 B loo d alcohol concentration o f 87 k ille d riders (5 A ustralian studies). COMPARISON BETWEEN MOTORCYCLE AND MOTORCAR ACCIDENTS Number o f Vehicle Users Affected by A Icohol Hossack and Brown3 listed blood alcohol levels detected in post-mortem examinations of 409 drivers killed in Victoria during the two periods, June 1970 to May 1971 and January 1972 to June An additional 35 drivers killed in the period were not tested. O f the 409 drivers 44% had a blood alcohol content in excess of 0.10 gm100 ml. Tonge14 reported on post-mortem examinations of 100% of the 323 car drivers killed in the Brisbane m etropolitan area from June 1968 to July Forty-six per cent of the drivers had a blood alcohol level in excess o f 0.10 gm ml. The post-mortem examinations of 253 killed motorcycle riders in the five Australian studies indicated that 26% o f the riders had a blood alcohol level exceeding 0.10 gm ml. The proportion of motorcycle riders exceeding 0.10 gm100 ml is significantly lower than the proportions of car drivers exceeding the same level in both comparison groups (X 2 = 4.65,p <.001 and X = 4.94,? <.001, for comparisons with the above two studies, respectively). Blood Alcohol Levels R obertson10 showed blood alcohol concentration recorded in breathalyser tests of motorcar drivers from six Australian States. The drivers had drawn police attention to them selves either by aberrant driving behaviour or by involvement in a non-fatal accident. D ata

9 46 M. Williams from injured or dead drivers and from the approximately 10% of drivers who refused the breathalyser test were not included. In the absence o f any detailed study of injured drivers these data can be compared with the distribution of blood alcohol levels recorded in 111 motorcycle riders who had a positive blood alcohol reading in the present study (Figure 7). The comparisons must be treated with caution because the two groups of operators differ, however, Robertson11 claimed that the actual values o f the BAC distributions found in dead crash victims, in surviving crash participants and in aberrant drivers breathalysed by police were rather similar, with mean values o f the order of gm100 ml. B.A.C. (gm100 ml) Figure 7 Com parison o f blood alcohol concentrations in 111 killed or injured m otorcycle riders an d B reathalysed drivers. The distributions shown in Figure 7 are similar. They both peak at a blood alcohol concentration above 0.15 gm100 ml and the proportions of operators with a particular BAC are alike. The notable difference is the absence of very high blood alcohol levels (above 0.30 gm ml) in the case of motorcycle riders. Age of Drinking Road Users The ages o f breathalysed drivers (Robertson10) have been compared with the age distribution of 137 motorcycle riders who were suspected of having used alcohol prior to an accident in the present study (Figure 8). The drinking motorcycle riders were almost exclusively younger than 25 years of age. While 87% of the motorcycle riders were within this age group, only 35% of the drivers were o f similar age. This is the principal difference between the two populations of road users and can probably be explained in terms o f the com parative youthfulness o f motorcycle riders.

10 Motorcycle Accidents and Alcohol Use _ PERCENT 40 W DRIVERS ( n =22352) 30 RIDERS (n =137) % Figure JL _L _L l u i n i i AGE Comparison o f ages o f 137 drinking riders and Breathalysed drivers. CONCLUSIONS It has been established that alcohol use is an im portant factor in motorcycle accidents, particularly fatal accidents. Alcohol affected riders are significantly overinvolved in fatal and single vehicle accidents. They are predominantly younger than twenty-five years of age, but this appears to be a result of the youthfulness of the motorcycle riding population. Blood alcohol levels attained by m any drinking riders are typical o f those found in problem drinkers. Significantly fewer killed motorcycle riders are affected by alcohol than killed car drivers. However, the levels of blood alcohol attained in comparable groups of riders and drivers are similar. Alcohol-affected motorcycle riders are significantly younger than their car driving counterparts. These findings contradict the widespread belief that it is impossible for a rider even to begin to operate a motorcycle when affected by alcohol. However, they do indicate that riding ability is seriously impaired by the ingestion of alcohol. This is borne out by the over involvem ent o f alcohol affected riders in single vehicle accidents.

11 48 M. Williams REFERENCES 1. Berenguel, A. P., A Motorcycle Accident Study, Iowa Department o f Public Safety, December Graham, J. W., Fatal Motorcycle Accidents, Journal o f Forensic Sciences, 14:1, Hossack, D. and Brown, G., The Hard Facts of the Influence of Alcohol on Serious Road Accident Casualties, Medical Journal o f Australia, 2:473, Jamieson, K. G. and Tait, I. A., Traffic Injury in Brisbane, National Health and Medical Research Council, Special Report No. 13, Marsden, W. E., Motorcycle Fatalities in San Diego County: A Study of Drinking Motorcycle Riders, Origin Unknown, Raeder, P. K. and Negri, D. B., An Evaluation of Motor Vehicle Accidents Involving Motorcycles, New York State Department o f Motor Vehicles, Research Report, No , Rankin, J. G., The Effects of Alcohol on Driving Efficiency, Medical Journal of Australia, 2:718, Raymond, A., Drivers Breathalysed in Melbourne in 1967, Proceedings, Australian Road Research Board, 5:209, Road Safety and Traffic Authority, Victoria, Personal Communication Regarding Ages of 1268 Motorcycle Riders Involved in Casualty Accidents in Victoria in Robertson, J. S., Blood Alcohol Concentrations in Drivers Breathalysed by Police in Six Australian States, National Road Safety Symposium, Australian Government Publishing Service, Canberra, Robertson, J. S., Dimensions of the Drink-Driving Problem, Road Safety and the Law Seminar, Australian Government Publishing Service, Canberra, Santamaria, J. N., Treatment of the Drinking Traffic Offender, Medical Journal of Australia, 2:74, Smith, D. I., An Investigation to Determine whether Blood Alcohol Tests should be made Compulsory for all Traffic Accident Casualties over the Age of 15 Years Admitted to Hospital in Western Australia, Road Traffic Authority, Perth, W.A., Undated. 14. Tonge, J. I., Post-mortem Blood Alcohol Levels in Road Accident Victims, National Road Safety Symposium, Australian Government Publishing Service, Canberra, Western Australia, Report of the Government Chemical Laboratories, Western Australia, Report of the Government Chemical Laboratories, 1974.