Motorcyclists, Pedestrians, and Alcohol

Susan P. Baker3

INTRODUCTION

In connection with highway travel, the ultimate goal is to reduce the number of highway deaths and the num ber and severity of injuries that are at least partly attributable to alcohol and other drugs.

It is im portant that we should keep sight of the wide variety of available approaches. They can be divided into four categories, none of which is sufficient by itself, none of which should be excluded: first, reductions in the am ount or changes in the patterns of use o f alcohol and other drugs; second, reductions in the degree of impairment produced when alcohol and other drugs are used; third, reductions in the am ount of travel or changes in the character­istics o f travel by people who are impaired by alcohol and other drugs; and fourth, reductions in the probability o f injury and severity o f its consequences when impaired people use our roadways, either as vehicle operators or as pedestrians.

My own remarks come under the fourth category. My primary purpose is to direct atten­tion to the im portance of tailoring our transportation systems and environments to meet the needs o f people who are impaired, whether they are impaired by the use of alcohol or drugs, or by other physical or mental disabilities or limitations.

In particular, I will speak about motorcyclists and pedestrians, two groups that face the traffic environm ent without the protection o f enclosed occupant compartments. Much of my discussion will be based on similarities between motorcyclists and pedestrians, especially as regards the scientific approaches that are likely to give them greater protection.

First, however, I would like to describe the size of the problem of motorcycle and ped­estrian fatalities, in terms o f both death rates and the importance of alcohol.

DEATH RATES

In 1975, o f an estimated 210 million U.S. residents, some 8600 were killed as pedestrians, 2800 as motorcyclists. There are jnany ways o f converting numbers of deaths to death rates, for various modes o f travel. The num ber of deaths can be related, for example, to:

the num ber o f people in the population; the num ber o f registered vehicles; the miles travelled by various types of vehicles; or the miles travelled by people using various modes o f transport.

The latter, which can be expressed as the num ber of deaths per 100 million person-miles o f travel, is especially helpful when we want to appraise the risks o f moving people in various ways.

a Associate Professor of Public Health Administration, The John Hopkins School of Hygiene and Public Health, Baltimore, Maryland, U.S.A.The research concerning motorcyclists and pedestrians killed in Maryland was supported by the Insurance Institute for Highway Safety and the Maryland Medical-Legal Foundation. The co-operation of the Maryland State Police, Baltimore Police Department, and Instituto Medico-Legal in Guanabara, Brazil, is gratefully acknowledged.

32

Motorcyclists, Pedestrians, and Alcohol 33

It will not come as a surprise to you that motorcyclists have an extremely high death rate per mile travelled: In the United States, the estimated rate in 1975 was roughly 11 deaths per 100 million person-miles o f travel, or more than five times the rate for car occupants. 12’ 15 W hat surprises most people is that the death rate for pedestrians is probably even higher: assuming that U.S. residents averaged half a mile daily as pedestrians, their death rate in 1975 was 22 per 100 million miles. (Even if we averaged as much as three-quarters o f a mile daily, the death rate was about fifteen. It is unlikely that U.S. residents walk that much, since surveys show that the average in less-motorised England is 1.2 kilometres, or about0.75 miles. 18 Similar surveys are needed in the U.S. and elsewhere.)

It is tempting to try to ‘explain away’ this figure by saying that for most pedestrians the risks are really a lot lower, that most o f the pedestrians who are killed are impaired by alcohol or extreme youth or the limitations of old age. But there are two reasons that we should not yield to the temptation. First, the statement is not always true: for example, although children, the elderly and people impaired by alcohol constitute about three-quarters of the pedestrians killed in Baltimore, these three groups constitute only one-quarter of the pedestrians killed in Rio de Janeiro . 1 2 (Figure 1 shows the difference between Baltimore and Rio in age distribution of pedestrian fatalities.) Second, and far more important, attempts to ‘explain away’ high death rates can distract us from coming to grips with a major problem and its solution.

,20CDCOCD"O<D

CL

O 10

I 1 1-0 -9 10-19 20-29 30-39 40-49 50'59 60*69 70+

Age

Figure 1 Percent distribution by age o f pedestrians killed in Baltimore and Rio deJaneiro.

ALCOHOL AS A FACTOR

It has long been recognised that alcohol is an important factor in adult pedestrian fatalities. Haddon, et al, 13 in New York City, Birrell5 in Victoria, and investigators elsewhere have found high blood alcohol concentrations (BACs) in large proportions of the fatally injured adult pedestrians. In both New York City and Baltimore, 113 for example, more than one-third had BACs of 100 m g /100 ml or higher. In Rio de Janeiro, even though alcohol-impaired pedestrians constitute a much smaller proportion of adult fatalities than in Baltimore, the number of alcohol-impaired pedestrians age 15-64 who are killed, per 100 000 population of that age, is more than twice as high as in Baltimore.

The importance of alcohol in motorcycle fatalities, in contrast to pedestrian fatalities, has not been widely reported or recognised. Therefore I would like to describe our findings in Maryland.

34 S. P. Baker

Recently, with Dr Russell Fisher, who is Chief Medical Examiner for the State of Maryland, I reviewed police and medical examiner records for all of the motorcyclists killed in Maryland from January 1973 to June 1975.3 During this period, there were:

99 fatal motorcycle crashes;63 involving other moving vehicles;91 motorcycle drivers killed;12 passengers killed.Sixty-two o f the 91 drivers who died were tested for alcohol. BACs were not determined

for the remainder because they survived more than four hours or (in 6 cases) because the blood sample was lost, contaminated or not drawn. The drivers who were tested did not differ significantly from those who were not tested in age. time of crash, or whether they were responsible for the crash.

The results clearly demonstrated the importance of alcohol. Of the 62 drivers tested for alcohol:

41 (66%) had measurable BACs;31 (50%) had BACs > 100 m g /100 ml;the median positive BAC was 140 m g /100 ml.Negative tests for alcohol were most common among motorcycle drivers who appeared

not to have been responsible for causing the crashes — that is, they were struck in the rear, or by a vehicle that failed to yield the right of way or was travelling in the wrong lane (Figure 2 ).

N 27 N = 15 N - 17 10 ° r r — ------------------------------- ----------------

90 -

80 -

SINGLE MULTI APPARENTLYVEHICLE VEHICLE NOT

RESPONSIBLEAPPARENTLY RESPONSIBLE ----------------------

Figure 2 Blood alcohol concentrations o f m otorcycle drivers in relation to responsibility for crash.

Motorcyclists, Pedestrians, and Alcohol 35

As one might expect, alcohol was most common in night-time crashes. It should be noted, however, that even in daytime crashes (between 6 a.m. and 6 p.m.) five of eighteen drivers killed had BACs of 100 m g /100 ml or greater. High BACs were especially common in the age group 20-34: about two-thirds had BACs of 100 m g /100 ml or more, compared with one- fifth of the drivers of other ages.

TABLE I B lood alcohol concentration by police report o f driver condition.

Blood alcohol concentration of

driver, m g/100 mlApparently

Normal

Driver Condition (Police Report)

Had been Condition drinking Unknown Total

0 16 1 4 2110-40 0 1 5 650-90 1 1 2 4

100-140 3 4 4 11150-190 4 3 7 14200 + 2 2 2 6

Total tested 26 12 24 62Unknown 20 8 9 37

Total 46 20 33 99

The police reports greatly underreported the presence of alcohol (Table 1). They categorised only 20% of all motorcycle drivers in this study (and only nine of the 31 drivers whose BACs were 100 m g /100 ml or higher) as ‘had been drinking’. Underreporting of alcohol is readily understandable since an accurate appraisal of the driver’s condition is difficult even when he is alive. It is important, however, that conclusions about alcohol im pairm ent should not be based on information from police reports. Since we lack chemical tests on surviving drivers, we do not know what proportion of the motorcyclists involved in all Maryland crashes have been drinking. The true proportion undoubtedly is much greater than the 3% that has been reported . 16

The presence of alcohol in illegally high concentrations in half of the motorcycle oper­ators killed in Maryland and tested for alcohol is especially noteworthy because — even though similar findings were reported from California a decade ago8— essentially no attention is given to alcohol in educational programs or materials describing important factors in motor­cycle crash causation.

DISCUSSION

In many respects, our highway transportation system is geared to the capabilities of the ‘aver­age’ driver, cyclist, or pedestrian, performing at optimal levels. We expect users of the system to be able to see and read well, to obey all the rules, to pay attention, to react quickly, to adjust to the deficiencies o f vehicles and roads, to compensate for failure on the part o f other users.

The prevalence o f high blood alcohol concentrations among fatally injured motorcyclists and pedestrians underscores the fact that the impaired person is not adequately protected by a system that assumes optimal performance. On the other hand, everyone could be protected by a system tailored to the needs and capabilities of the impaired person.

In general, such a system would be based on approaches that minimise the need for individuals to make the correct decisions and follow difficult or unappealing courses of action .4- 11 A wide variety of approaches has been described elsewhere7-10-l4, so I will mention

36 S. P. Baker

only a few examples. They are not new, but I urge you to consider the fact that they will protect the unperceptive, the unco-ordinated, and those unable to concentrate, comprehend, and decide among complex alternatives. They also will protect people like you. The examples illustrate three basic phases o f prevention .9

The first phase is aimed at reducing the likelihood of collisions. Examples include incor­porating reflective materials into coats, shoes, and motorcycle components to improve the visibility o f pedestrians and cyclists; limiting the speed capabilities o f motorcycles and other vehicles; restricting vehicle use in areas used by pedestrians, or vice versa; putting signalised pedestrian crossings away from intersections to simplify the task of crossing the street; and providing separate lanes for motorcycles.

The second phase is reducing the hum an damage when collisions occur. Examples include requiring helmet-use by all motorcyclists17 (although this does require individual co­operation, the routine wearing o f helmets may foster helmet use by motorcyclists who are im paired by alcohol. W hen helm et use is optional, on the other hand, impairment by alcohol may disproportionately reduce the likelihood o f helmets being worn by the very people who are probably at greatest risk o f being involved in serious motorcycle crashes); modifying those portions o f vehicles that are likely to contact pedestrians or motorcyclists (for instance, by removing projections or rounding them so as to spread the forces over a larger part of the body); removing sharp edges and projections from roadside markers.

The third phase is improving survival and minimising the adverse results of injury. An example would be testing survivors for alcohol in order to improve the diagnosis and treatment o f their injuries.6

The approaches that are chosen should depend upon what is likely to work — for example, travel environments where the routes most likely to be chosen are also the safest routes.2 ,12 In illustration, let me describe two types o f crossings I saw, not far from one another, on a highway in Mexico’s Baja California. One crossing was for people, and had long flights o f steps up to a pedestrian bridge. No one was using it; it was easier to run across the road. For the other crossing, the level o f the road had been raised slightly and underneath was a wide, gently sloping underpass. It had been especially designed so that cows would choose to use it — and they did. I believe we could come closer to solving the pedestrian problem if, in similar fashion, we took advantage o f people’s tendency to go the easy way, and built safe routes that will be used because they are the easiest way to go.2 Such routes would be used by everyone, im paired or not.

In summary, greater emphasis needs to be placed on travel environments that can be easily and safely negotiated by people who are impaired by alcohol or other drugs or by any sort o f disability. M easures that protect these high-risk travellers will protect others as well, and thus will serve everyone while reducing alcohol-associated deaths and injuries.

REFERENCES

1. Baker, S. P., ‘Pedestrian Deaths in Rio de Janeiro and Baltimore’, Accident A nalysis and Prevention, in press.

2. Baker, S. P., ‘The Man in the Street: A Tale of Two Cities’, American Journal of Public Health, 65: 524-525^ 1975.

3. Baker, S. P., Fisher, R. S., ‘Alcohol and Motorcycle Fatalities’, American Journal o f Public Health, in press.

4. Barry, P. Z., ‘Individual Versus Community Orientation in Prevention of Injuries’, Preventive Medi­cine, 4: 47-56, 1975.

5. Birrell, J. H. W., ‘A Comparison o f the Post-Mortem Blood-Alcohol Levels of Drivers and Passen­gers Compared With Those o f Drinking Drivers Who Kill Pedestrians’, Medical Journal of Aus­tralia, 2 : 945-948, 1971.

6. Champion, H. R., Caplan, Y., Baker, S.P., et al.,‘Alcohol Intoxication and Serum Osmolality , Lancet, 2: 1402-4, 1975.

Motorcyclists, Pedestrians, and Alcohol 37

7. Drysdale, W. F., Kraus, J. F., Franti, C. E., Riggins, R. S., ‘Injury Patterns in Motorcycle Collisions’, Journal of Trauma, 15: 99-115, 1975.

8. Graham, J. W., ‘Fatal Motorcycle Accidents’, Journal of Forensic Sciences, 14: 79-86, 1969.9. Haddon, W., Jr., ‘A Logical Framework for Categorising Highway Safety Phenomena and Activity’,

Journal of Trauma, 12: 193-207, 1972.10. Haddon, W., Jr., ‘Reducing the Damage of Motor Vehicle Use’, Massachusetts Institute of Tech­

nology, Technology Review, July-August, 52-59, 1976.11. Haddon, W., Jr., ‘Strategy in Preventive Medicine: Passive Versus Active Approaches to Reducing

Human Wastage’, Journal o f Trauma, 14: 353-359, 1974.12. Haddon, W., Jr., Baker, S. P., ‘Injury Control’, in Clark, D. W., MacMahon, B. (editors), Preventive

Medicine, 2nd edition, Little, Brown, and Company. To be published.13. Haddon, W., Jr., Valien, P., McCarroll, J. R., Umberger, C. J., ‘A Controlled Investigation of

the Characteristics of Adult Pedestrians Fatally Injured by Motor Vehicles in Manhattan’, Journal of Chronic Disease, 14: 655-678, 1961.

14. Kraus, J. F., Riggins, R. S., Franti, C. E., ‘Some Epidemiologic Features of Motorcycle Collision Injuries’, American Journal of Epidemiology, 102: 74-98, 1975.

15. National Safety Council, Accident Facts, 1976 Edition. Chicago, National Safety Council, 1976.16. Reiss, M. L., Berger, W. G., Valette, G. R., Analysis of Motorcycle Accidents and Statistics. Motor­

cycle Safety Foundation, Elkridge, 1974.17. Robertson, L. S., ‘An Instance of Effective Legal Regulation: Motorcyclist Helmet and Daytime

Headlamp Use Laws’, Law and Society Review, 10: 467-477, 1976.18. Smeed, R. J., ‘Pedestrian Accidents’, Proceedings of the International Conference on Pedestrian

Safety, Haifa, Israel: Technion, 1976.