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Reducing the Costs of Dnnking and Driving DAVIl) S. REED INTRODUCTION Public concern over the dangers of drunken driving is almost as old as the automobile. Indeed, few authors on the subject can resist citing the "motor wagons" editorial in the Quarterly Journal of Inebriety in 1904. Despite the long history of concern and the many attempts to control the problem, drunken driving is still perceived as a major highway safety problem. Paradoxically, the widespread familiarity in our society with drinking, driving, and their combination may have hindered the development of effective countermeasures. An individual who is very familiar with the elements of a problem may let preconceived notions interfere with the gathering, assimilating, and applying of information. The first section of this paper examines the costs generated by the drinking-driving prob- lem, what part of these costs are potentially preventable, and how the magnitude and distribution of costs might be viewed in assessing the priority of the problem. The next section taps the extensive experience worldwide with programs to reduce drunken driving. We find some David S. Reed, a doctoral candidate in the program in public policy at the John F. Kennedy School of Government, Harvard University, is currently an intern at the Federal Communications Commission. This work was completed during my enrollment at the John F. Kennedy School of Government, Harvard University. I would particularly like to thank Mark Moore and Dean Gerstein, who supervised its preparation. 336
Reducing the Costs of Drinking and Driving 337 promising avenues for future action and equally important some un- promising avenues that still have vocal advocates. The following section examines efforts to reduce the risk associated with a given amount of drunken driving. Because there have been few such efforts, this section offers few conclusions; it does raise questions that seem to warrant further investigation. -I- The final section examines the manner in which the federal govern- ment has designed and managed programs of drinking-driving counter- measures. It concludes that changes are necessary if we are to learn from experience and improve our ability to reduce the costs of drunken . · . arlvlng. COSTS AND THEIR IMPLICATIONS FOR THE ROLE OF GOVERNMENT THE NEED FOR EVALUATION Any attempt to ameliorate dr~nking-driving problems will consume scarce government resources and may impose monetary and nonmo- netary costs (such as some restriction of civil liberties) on individuals. We must therefore determine the costs generated by the problem in order to compare them with the costs imposed by possible solutions. This section examines the magnitude and distribution of costs resulting from drunken driving. It also provides information to help determine the priority of reducing this problem by governmental efforts. This question of costs is of more than academic interest. The comp- troller general of the U.S. (1979, p. 3) estimates that "Federal, State, and local governments spent over $100 million in 1976 for their drinking- driver countermeasure activities." This level of resources, and, as we discuss below, the large human and economic costs potentially at stake suggest the importance of determining the appropriate role of govern- ment in efforts to reduce the costs of drunken driving. PREVENTABLE ACCIDENTS Information presented to policy makers about drunken driving (U.S. Department of Transportation 1968, Noble 1978a, Comptroller General of the U.S. 1979) has typically expressed the importance of the problem in terms of the costs associated with it. For example, Noble (1978a, p. 61) reports that "approximately one-third of the . . . injuries and one- half of the fatalities [from traffic accidents] are alcohol related." The term "alcohol-related" refers to any accident in which a driver, or some-
338 REED TABLE 1 Percentage of Accident-Involved Drivers and Control Group Drivers Found to Be Within Various BAC Ranges, by Worst Consequence of Accident and Place and Time of Study Fatal,a Vermont, Huntsville, Ala., 1967-1968, 197~1975, BAC (%) Ar~itlent/~natro1 A~nirlent/(~nntrn1 injury, Grand Rapids, Mich., 1962-1963, Accident/Control Property Damage, Grand Rapids, Mich., 1962-1963, Accident/Control <0.01 64~o 84% 0.01~.049 5% 9% 0.05 0~999) 0.10 0.149~31% ~0.015 ~ 73.98~o 88.18% 4.86% 4.29~o 7.97% 4.6B~o 4.84~o 2.11% 8.35% 0.74% ) 81.83~o 89.01% 6.55% 7.76% 4.11~o 2.46% 83.87% 89.01% 6.89% 7.76% 3.54% 2.46% 0.76% 5.70% 0.76% a Vermont data adjusted per Appendix B. Source: Appendix A. Note: BAC levels less than 0.01% are effectively equal to zero. The minimum BAC at which it is illegal to drive in most states is 0.10%. times any person involved in an accident, had a positive blood alcohol content (BAC).i Clearly, a better indication of the importance of solving a problem than calculating the associated costs would be to calculate the costs that would be eliminated if it were solved. To determine the maximum pre- ventable costs of drunken driving, I first examine the BAC levels of drivers involved in various types of accidents and those of control groups of drivers selected at random from times and places similar to those at which the accidents being controlled for occurred. Table 1 shows these data, which I have selected from several studies (also see Appendix A). As Table 1 shows, the BAC levels of drivers involved in more serious accidents are generally higher than those of drivers involved in less serious accidents. Once the distribution of BAC levels among accident-involved drivers and the control groups is known, it is possible to compute how many accidents would be avoided if all driving was done at the risk level associated with the lowest BAC level; that is, accidents that would be prevented by a "perfect" drinking-driving countermeasure. Appendix C demonstrates these computations, and the results are shown in Table 2. Since the figures in Table 2 are based on the association between ' Blood alcohol content (BAC) and the equivalent term blood alcohol concentration refer to the standard measure of the concentration of alcohol present in a person's body at a given time (not including any alcohol that has been drunk but not yet absorbed).
Reducing the Costs of Drinking and Driving 339 TABLE 2 Expected Reduction in Motor Vehicle Traffic Accidents If All Drivers Had a Zero BAC Type of Accident, Place and Time Expected Reduction Fatal, Vermont, 1967-1968 Injury, Huntsville, 197~1975 Injury, Grand Rapids, 1962-1963 Property damage, Grand Rapids, 1962-1963 23.7% 15.8% 8.2~o s.75rO Source: Appendix C. BAC and accident involvement, we must ask whether any other factors, correlated with both BAC while driving and accident risk, are con- founding our analysis. There appear to be two confounding factors bias- ing the results in opposite directions. First, there is evidence that greater frequency of drinking is positively associated with more frequent drun- ken driving and negatively associated with accident risk at any given BAC (Borkenstein et al. 1974, Hurst 1973~. As Appendix C shows, the risk of accident as computed from the data on Grand Rapids and Ver- mont is actually lower for the 0.10-0.049 BAC range than for the <0.01 range. The correlations with drinking frequency bias Table 2 toward underestimating the accident reduction, since those who currently drive drunk, if sober, would have a lower accident risk than those who cur- rently drive sober. The second bias results from a disputed but probable positive asso- ciation between "problem drinking" or "alcoholism" and both drunken driving and accident risk while sober (Smart 1969, Noble 1978b, pp. 238-240~. This bias would result in drunken drivers, as a group, having higher accident risk than the general driving population even if they were prevented from driving with positive BAC levels. Available information is not sufficient to quantify either of these biases, therefore I present the expected reductions in Table 2 as they are and hope that the biases are small or cancel each other out. A final caution is that my figures for maximum achievable accident reduction are based on samples at specific times and places. Their va- lidity for the nation as a whole is not ensured. It is heartening that the Huntsville and Grand Rapids studies of injury accidents, despite their spatial and temporal separation, yield reduction estimates within 8 per- centage points of each other. The Vermont data on distribution across
340 REED BAC ranges of drivers killed is in agreement with several other studies of driver fatalities (Jones and Joscelyn 1978, p. 12, Noble 1978b, pp. 233-240~.2 I have encountered no studies of property-damage-only crashes other than the Grand Rapids study. MAGNITUDE OF PREVENTABLE COSTS The figures on accident reduction can be roughly converted to savings in terms of lives, injuries, and dollars of property damage. In 1977, motor vehicle traffic accidents resulted in 49,500 deaths, 1.9 million disabling injuries, arid $15.5 billion of property damage in the United States (National Safety Council 1976~. (The $15.5 billion figure is based on $520 per accident-involved vehicle [Jones and Joscelyn 19783.) Mul- tiplying these figures by the percentages of accident reductions in Table 2 yields maximum achievable savings in 1977 of 11,700 deaths, 156,000 to 300,000 disabling injuries, and $963 million in property damage (based on the total reduction in accident-involved vehicles). Of course, like any estimates based on sketchy information, these figures must be interpreted with some care. The figures in Table 2 refer to reductions in the number of accidents, not directly to reductions in the consequences of accidents. For instance, alcohol-related accidents more frequently involve only a single car and driver than do accidents in general (Borkenstein et al. 1974, p. 105, Noble 1978b, p. 235~. There- fore, the reduction in the number of people killed, the number of people injured, and the number of cars damaged will be less than the reduction in number of accidents. It is also likely, however, that the average severity of injury and damage in the accidents prevented will be greater than the severity of injury and damage in accidents in general; therefore only in the case of fatalities do the above figures clearly overstate po- tential savings from drinking-driving countermeasures. It is beyond the scope of this paper to develop estimates of preventable costs for all other problems that may compete with drinking-driving for government resources. Table 3, however, provides some perspective. For example, we see from Table 3 that 22 percent of all accidental deaths resulted from alcohol-related traffic accidents and that 10 percent of accidental deaths would have been prevented if all drivers had zero BAC.3 2 I could not produce accident reduction estimates from these other studies because they lacked control groups. 3 Table assumes that 50 percent of all traffic accident deaths are alcohol related (Comp- troller General of the U.S. 1979, Noble 1978b), and that 23.7 percent of all traffic accident deaths would be prevented if all drivers had zero BAC (see Table 2~.
Reducing the Costs of Drinking and Driving TABLE 3 Deaths from Alcohol-Related Motor Vehicle Traffic Accidents, and Deaths Prevented If All Drivers Had Zero BAC as Percentages of Various Categories of Deaths, 1977 341 Cause of Death Related to Drinking-Driving Prevented If All Drivers Had Zero BAC Alcohol-related motor vehicle traffic accidents All motor vehicle traffic accidents All accidents All causes except cardiovascular diseases and malignancies All causes 100% 50% 22% 4% 1% 47% 24~o 10% Do 0% Source: Bureau of the Census (1978' pp. 75, 78~. In considering the data in Table 3, one should be aware that deaths caused by traffic accidents, particularly alcohol-related traffic accidents' occur typically among a younger age-group than deaths from other major causes. For example, Perrine et al. (1971, p. 46) report that of drivers killed in accidents, 47 percent were under 30 years of age, and of those with positive BAC levels, 49 percent were under 30. Many think that deaths of younger persons should be counted more heavily in making policy decisions, because each such death results in more years of life lost. Another problem of weighting involves deaths of drinking drivers themselves versus deaths of innocent victims of drinking-driving acci- dents. I estimate that 61 percent to 78 percent of persons killed in drinking-driving traffic accidents are drivers with positive BAC levels (see Appendix B). One may argue that since people can choose how much to drink before driving, it may not be the proper role of govern- ment to protect them from the consequences of a decision freely made. Alternatively, one might argue that people may drive after excessive drinking due to a momentary lapse of judgment, an episode of severe stress, or a habitual behavior pattern that is difficult to control (i.e., an "addictions. One study reports that 75 percent of drivers admit to driving after drinking at least occasionally (U.S. Department of Trans- portation 1968, p. 614.4 Viewed in this way, drunken driving looks less 4 This is not to say that 75 percent of drivers drive with the high BAC levels associated with greatly increased accident risk (see Table C-1 in Appendix C). However, there is evidence that less frequent drinkers, and less frequent drinking drivers, show elevated accident risk at lower BAC levels than does the drinking-driving population in general (Hurst 1973~.
342 REED like a risk some choose to take and more like a random risk to which many people will be exposed whether or not they would choose to in a moment of calm reflection. Furthermore, the death or injury of some- one who is driving drunk may impose costs on friends, loved ones, those dependent for financial support, and the economy in general. In setting policy, the proper weight to give to deaths of drunk drivers cannot be determined by empirical or logical analysis, although these may inform the decision. I feel that such deaths should be weighted equally to others for purposes of setting policy, but that we should be wary of providing perverse incentives to potential drunk drivers- a topic I address later in this paper. In conclusion, it seems that drinking-driving countermeasures can be legitimate and useful government actions, but that even if such coun- termeasures were perfectly successful, the savings in lives, injuries, and property loss would be less than widely quoted figures would lead one to believe. Which countermeasures show the best prospect of success is the topic of the rest of this paper. EXPOSURE REDUCTION OVE RVIEW The strategy of drinking-driving countermeasure that occurs first to most people is exposure reduction: reducing the amount of drunken driving that takes place and thereby reducing accident costs. This section ex- amines several potential ways of achieving exposure reduction: · General deterrence: countermeasures that seek to prevent drivers in general from combining driving with drinking in excess of legally prescribed limits (0.10 percent BAC in most states). · Recidivism reduction (specific deterrence): countermeasures that seek to specifically compel those people who have already been arrested for driving while intoxicated (DWI) not to drive drunk again. · Third-party intervention: countermeasures that seek to influence those around potential drunk drivers (servers of alcohol, fellow party guests, or bar patrons, etc.) to prevent them from driving while intox- icated. · Altering the legal minimum drinking age. · Screening the driving population for those most likely to drive drunk. · Installing devices in vehicles to automatically detect drunk drivers. · Providing alternative transportation for potential drunk drivers.
Reducing the Costs of Drinking and Driving GENERAL DETERRENCE Risk of Punishment 343 The most effective programs of general deterrence seem to have been those that raised drivers' perceived risk of arrest and punishment for drunk driving. The classic program of this type is the British Road Safety Act of 1967. The act "defined driving with a BAC of .08% or higher per se as an offense," and "gave police the power to require pre-arrest roadside tests [for breath alcohol] from drivers who had been involved in traffic accidents or moving violations or where there was reasonable cause to suspect them of drinking and driving. Drivers who refused to provide a breath test were considered guilty" (Cameron 1978, p. 22~. Passage of the act was accompanied by a great deal of publicity and public awareness of its provisions (Jones and Joscelyn 1978, pp. 66-67~. The immediate impact of the act was positive and dramatic. For the 3 months following passage of the act, casualties from traffic accidents were reduced 16 percent from the same period the previous year, and fatalities were reduced 23 percent (Ross 1973, p. 20~. The percentage of fatally injured drivers with BAC levels of greater than or equal to 0.08 percent dropped from 27 percent before passage to 17 percent the following year (Comptroller General of the U.S. 1979, p. 27~. A careful quasi-experimental study by Ross (1973) attributed these reductions substantially to the act and the wide publicity it received. He also noted (p. 75~: Unfortunately. there are many signs that the initial effect of the legislation is diminishing. Although there are problems in speculating on what would have happened in the absence of the legislation, the significant change in the slope of the casualty rate curves . . . suggests that the savings achieved ought to be regarded as temporary. This conclusion is bolstered by the fact that blood analysis of fatalities shows that the initial drop in the percentage with an illegal alcohol concentration. from 25 percent in 1967 to 15 percent in 1968, was progressively diminished and the percentage has now returned to its former level. The trend noted by Ross appears to have continued. By 1975 the percentage of drivers killed in England and Wales in road accidents with a BAC level of 0.08 percent or more had reached 36 percent, substan- tially above its pre-1967 level (Comptroller General of the U.S. 1979, p. 27~. The explanation offered by Ross ( 1973, pp. 75-78), which has achieved wide acceptance, is that the well-publicized passage of the act convinced
344 REED many drivers that the risk of arrest when driving drunk had become much higher than it used to be be. Potential drunk drivers were deterred by the threat of arrest and punishment. As time went on, however, drivers realized that enforcement was rather slack and that risk of arrest was not all that high. This realization caused an "evaporation" of the act's deterrent effect.5 In September 1975, the Cheshire County Police seemed to recapture the Road Safety Act's deterrent effect through a publicized policy of administering breath tests to all drivers pulled over for violations or involved in accidents during "drinking hours." The resulting accident reduction "evaporated" a month after the policy came to a publicized end (Ross 1977~. How applicable is Britain's experience to that of the United States? Ross (1973, p. 1) asserts that "in broad culture and narrower legal structure Britain is the closest of European countries to the United States." Comparative statistics indicate that Britain is very similar to the United States in number of traffic fatalities per vehicle mile (Borkenstein et al. 1974, p. 20) and has a slightly smaller representation of alcohol- influenced drivers among driver fatalities (Organisation for Economic Co-operation and Development 1978, p. 25~. More convincing is the fact that the Road Safety Act experience has been partially replicated in countries other than Britain. As Robertson (1977, p. 6) describes: A law providing for breath testing and penalties for blood alcohol above .08~o by weight or refusing the test came into force in Canada in 1969 but with less widely publicized predictions of increased chances of arrest than in Britain. Death rates were about 8 percent less than expected in the subsequent two years but, again, the effect of the law was temporary. After 2 years of the law, death rates in Canada returned to levels that would have been expected without the law. In 1978, France amended its drunk-driving law to allow police to 5 There are alternatives to the "evaporation" theory regarding the British Road Safety Act. In support of alternative or supplementary explanations. we should note that since the date of Ross's study, incidence of illegally high BAC levels among drivers killed in Britain has continued to climb, until it now substantially exceeds the incidence before passage of the act. Mere evaporation of the deterrent effect cannot account for this. Other factories) must be strengthening the association between BAC level and driver fatalities over time. It is not certain how much of what Ross observed was due to "evaporation" and how much was the result of the aforementioned unidentified factories). The "evaporation" theory, however, is still attractive as a partial explanation. It is well grounded in theory and predicts the outcomes of several other programs patterned after the British Road Safety Act.
Reducing the Costs of Drinking and Driving 345 administer breath tests to drivers even in the absence of an accident or traffic violation. Dorozynski and Volnay (1978, p. 44) describe the initial effects (presented here in translation): A certain number of [breath testing] operations were organized immediately, [and] announced in the press, in several French provinces and in Paris. Their results were entirely unexpected: less than O.S~o of the "alcooltests" were pos- itive, and in Paris, zero. Taking account of what is known of the accuracy of the "alcooltest," and of its sensitivity, this roughly indicates that the "French at the wheel" had stopped drinking. While the information from France so far is too sketchy to tell us anything, it does not appear inconsistent with Ross' observations in Britain. Unfortunately, the only agreed-upon success in the United States similar to the British Road Safety Act was a 1-year countermeasure program at Lackland Air Force Base, Texas, in 1959. While the program achieved "a statistically significant decrease of 50% to 60% in the num- ber and rate of accidents, driver injuries, and other injuries during the operational period" (Cameron 1978, p. 23), it is not clear how applicable this experience would be to a civilian environment. Despite the lack of documented successes in the United States for countermeasures to deter drunken driving by increasing the risk of arrest and punishment, this approach appears to have won favor among state highway safety officials. A recent survey by the U.S. General Account- ing Office (Comptroller General of the U.S. 1979) asked officials from the 50 states, the District of Columbia, and Puerto Rico to choose and rank the three most important current or past efforts in their state to combat drunken driving. "Instituting or increasing the use of special police patrols for the drinking driver" was ranked number one by 25 percent of respondents, more than any of the other nine responses. Another 27 percent of respondents ranked it second. Of six states examined in depth in the GAO report (California, Geor- gia, Louisiana, Minnesota, New York, Washington state), five were operating some police patrols targeted at drinking drivers, four reported increased numbers of driving while intoxicated (DWI) arrests, and two reported evaluations of the patrol's effect on accident rates. In King County, Washington, a "drinking-driver emphasis patrol" was operated as part of the federally funded Alcohol Safety Action Project (ASAP). Evaluation failed to find a change in accident fatalities or injuries re- sulting from the patrol, although DWI arrests had increased. In Hen-
346 REED nepin County, Minnesota, emphasis patrols were also operated as part of ASAP. "Alcohol involvement in fatal crashes was reduced from 63 percent in 1972 to 38 percent in 1976" (Comptroller General of the U.S. 1979, p. 22~. Even in the absence of a control group, this finding is very suggestive of success. From present evidence, then, it appears that when drivers' perceived risk of arrest and punishment for drunk driving is sufficiently increased, drunk driving is deterred and accidents are reduced. In Britain, fatalities from traffic accidents decreased by 23 percent in response to the Road Safety Act, and similar legislation in Canada brought about a temporary reduction of 8 percent. In order to sustain a high perceived risk of arrest and punishment, the risk must be made high and kept high. Targeting patrols by day of week, time, and geographic location; legislative and technical progress toward making breath tests for alcohol easier to administer; and simplifying the process of making a DWI arrest and providing police with motivation to make such arrests are all ways to increase the risk of arrest. Using such methods, ASAPs were able to double and triple the number of DWI arrests, although it is unclear how much of this increase resulted merely from charging drivers with DWI rather than a specific moving violation (Zimring 1978 pp. 151- 152~. What remains unknown is just what levels of risk are necessary to achieve various degrees of deterrence and what it would cost to bring about such increases in risk. These questions appear to require empirical study. Severity of Punishment If increasing risk of punishment can deter drunken driving, then what about increasing severity of punishment? It seems at first glance easier and less expensive to hand out stiffer penalties to convicted drinking drivers than to beef up enforcement. The archetypes of the severe pun- ishment approach are the Scandinavian countries. Imprisonment or fines exceeding one-tenth of the convicted person's after-tax income, com- bined with license suspensions exceeding 1 year, are common punish- ments for first DWI offense in these countries. The Scandinavian drunk-driving laws are widely reputed to be effec- tive deterrents, and there is anecdotal evidence in accord with this rep- utation, but during a 3-month study in Scandinavia, Ross (1975) was unable to find any scientific evidence that the laws had deterrent effects. He then performed time series analyses of drunk driving and traffic
Reducing the Costs of Drinking and Driving 347 casualty measures in Sweden, Norway, and Finland. In no case did these measures change systematically with changes in drunk-driving laws so as to indicate a causal relationship. Of course, the failure to demonstrate the laws' efficacy does not prove them ineffective. The Scandinavian laws are quite old and have changed only gradually over the years, hampering time series analysis. Since there is no scientific evidence of the Scandinavian laws' effec- tiveness, and since cultural traditions such as drinking in large quan- tities when drinking may be adequate to account for the anecdotal reports of differences with American drinking and driving behavior, we must look elsewhere to try to assess the potential of deterrence through severe punishment. A less well-known test of the severe punishment approach occurred in the United States in Chicago. For 7 months during 1970 and 1971, "magistrates in Chicago's traffic courts were directed by the supervising judge to sentence persons convicted of driving while intoxicated (DWI) to seven days in jail and to recommend to the Secretary of State's office that such drivers' licenses be suspended for one year. The policy was publicly announced and widely publicized" (Robertson et al. 1973, p. 57~. While motor vehicle fatalities decreased during this period, eval- uators concluded that the decrease was not statistically significant com- pared with variations during the preceding 5 years and noted a similar decline during the period in another, similar city without such a program. The Chicago program's failure could be attributed to a frequently identified pitfall of this approach judges, juries, and even police and prosecutors are thought to be reluctant to subject DWI offenders to severe punishment. Up to 75 percent of drivers admit to driving after drinking at least occasionally (U.S. Department of Transportation 1968, p. 61), so many people in our society do not view driving after drinking as deviant behavior. If the general feeling of the public is "there but for the grace of God go I," it is doubtful that severe penalties will be applied often even if they are authorized by law. In fact, what DWI offenders do is unusual. In order to achieve a high enough BAC level to be considered intoxicated in most states, a person weighing 140 pounds would have to consume four to five drinks within an hour (more if he or she were drinking on a full stomach), a "drink" being 12 ounces of beer, 3 ounces of wine, or 1 ounce of 80- to 90-proof spirits. A typical BAC level for a person brought to trial for DWI is 0.15 percent and would be the result of consuming six to seven drinks. It is probably safe to say that most drivers have never driven after consuming this much alcohol.
348 REED Severe penalties for drunk driving may nevertheless result in fewer arrests, fewer convictions, and more plea bargaining. In the Chicago experiment it is unknown how frequently judges actually complied with the supervising judge's instructions to give 7-day jail sentences for DWI convictions. It is known that DWI arrest levels did not change signifi- cantly, but there was a decrease in the number of convictions, accounted for by a decrease in the conviction rate for defendants who did not undergo a test for alcohol after arrest. "tT]his change appears to be a result of changes in plea bargaining or reluctance of judges or juries to convict and sentence to seven days in jail those drivers for whom ob- jective evidence of impairment was not available" (Robertson et al. 1973, p. 66~. The difficulty of convicting any but the most blatantly impaired may be the reason that a Norwegian government committee, in the wake of Ross' Scandinavian study, has recommended abolishing the mandatory prison term for DWI convictions with a BAC level of 0.05-0.12 percent, and reducing the mandatory prison sentence for those convicted with BAC levels exceeding 0.12 percent from 21 days to 7 days (Comptroller General of the U.S. 1979, pp. 31-32~. Even if judges and juries could be educated to adopt severe sentences for DWIs, there is a question of how severe a penalty we as a society are willing to levy for this crime. A 7-day jail sentence may not be severe enough to achieve significantly more deterrence than the risk of license suspension. We simply do not know at present what combinations of risk and penalty will achieve deterrence. I speculate, however, that people's behavior is relatively insensitive to changes in the seriousness of an adverse outcome that is viewed as very unlikely to occur. After all, those who currently drive drunk are not deterred by the small risk of a very severe penaltyaccidental death. While information is sparse, the most commonly accepted figure for the risk of arrest when driving while illegally intoxicated in the United States is 1 in 2,000 (Jones and Joscelyn 1978, p. 53) and in Britain, in the wake of the Road Safety Act, it was estimated to be 1 in 1,000 (Comptroller General of the U.S. 1979, p. 27~. In addition to the dubious potential for effectiveness, we should re- member that the severe punishment approach would not be as costless as it may seem. As the severity of penalties increases, the length of trials and number of appeals are likely to increase (assuming the penalties are not circumvented by plea bargaining), thus further crowding the over- burdened court system. If penalties are to include imprisonment, then the cost of a large addition to the country's prison population is part of the calculation.
Reducing the Costs of Drinking and Driving Public Information and Education 349 The third approach to achieving general deterrence is public information and education. In fact, a recent report by the U.S. General Accounting Office (Comptroller General of the U.S. 1979, p. i) makes this claim: Before any significant reduction in alcohol-related traffic accidents will occur, a long-term continuous educational commitment must be made. Governments, educational institutions, and the general public need to work together to change attitudes about drinking and driving. The report concludes that "the Secretary of Transportation should take the lead in a massive effort to start changing social attitudes about drinking and driving" (front cover). Is such a "massive effort" necessary? And would it be productive? Public education, taken in its broadest sense, would include programs to arrest drinking drivers and to subject them to punishment and/or other treatment. If the argument is thus trivialized, it is considerably strengthened but of less interest. Public education in a narrower sense means communication with the public through symbols rather than ac- tions. Furthermore, not all efforts at public information and education are intended to achieve general deterrence that is, not all are targeted at affecting the behavior of potential drinking drivers. For instance, the efforts included in the U.S. Department of Transportation's Alcohol Safety Action Project (ASAP) program were intended to build political support for countermeasure programs. The objectives, as stated by the U.S. Department of Transportation (Hawkins et al. 1976, p. 15), were: · Make the problem of alcohol-related crashes a higher priority among com- munity concerns. · Make key officials and professional groups (police, judiciary, etc.) aware that two-thirds of the drunk driving fatalities involve problem drinkers, rather than social drinkers. [This is a weakly supported assertion.] · Create support for the hypothesis that this relatively small segment of the driving population that abuses alcohol can be effectively controlled. · Inform key officials, professionals, and the public about modern counter- measure methods. The propriety of a federal agency's funding advertising campaigns to try to influence public priorities and to advance controversial scientific theories is open to question. This is not to underrate the importance of information and technology transfer to state and local governments. Another use of public information and education is to try to influence
350 RE ED third parties to intervene in potential drunk-driving situations (e.g., driving an intoxicated friend home from a party). This use is discussed later. There are three avenues for using public information and education to achieve general deterrence. The first is to inform potential drunk drivers of the risks they face accident and arrest- if they drive while drunk. The potential effectiveness of this avenue is dubious, since it appears that the public is quite familiar with these risks. A national opinion survey in the United States in 1973 found that "86 percent of the respondents rated drinking-driving as 'a very serious problem' in the United States and 78 percent felt that police and courts should be 'tougher than they are' " (Hawkins et al. 1976, p. 74~. A recent study in Canada (Wilde et al. 1975) asked members of the public to rank 40 traffic safety measures in order of effectiveness and in order of desir- ability. "Double penalties for drunk driving" rated second in effective- ness (behind "make the wearing of seat belts mandatory") and fourth in desirability. This information leads me to concur with Cameron (1978, p. 53) that: While the public might not always be aware of the specific details of the laws against drinking and driving or understand the more technical aspects of how alcohol affects the body, the majority of people are aware of the basic message, that drinking and driving is dangerous and is against the law. Thus, the drinking and driving behavior observed in the U.S. today is, generally speaking, char- acteristic of a fairly well informed and educated public. A campaign of public information and education that merely repeats what is generally known or fills in small details seems unlikely to cause much change in drinking-driving behavior. The second avenue is to use information and education to try to alter attitudes rather than provide informationthat is, to alter norms and standards of behavior of people who drink and drive so as to make drunk driving less likely. As Maloff et al. (1980) point out, norms con- cerning substance use are set and reinforced by a person's entire social environment, including family and peer group. An advertising campaign advocating conflicting norms is likely to be too weak a stimulus to have much effect and may be rejected out of hand as an attack on the groups an individual identifies with. An example of the apparent failure of a public information and ed- ucation campaign to effect a desired attitude change is described by Hochheimer (in this volume) with regard to the Australian "Stop a Slob from Driving" campaign: The idea was to portray drinking drivers as slobs; since people would not want to be perceived as slobs, they would reduce their alcohol-related driving. Instead,
Reducing the Costs of Drinking and Driving 351 many people found "Mr. Slob" to be funny, attractive, a person they wouldn't mind being like. This incident represents more than a random backfiring of an adver- tising campaign. The campaign was undertaken because many Austra- lians perceived drunk driving as an acceptable, even attractive thing to do. Thus, any character presented as a drunk driver already had an advantage with the campaign's target audience. The potential for re- ducing drunk driving by altering attitudes of potential drunk drivers through such campaigns seems quite limited. A final avenue is to use public information and education to provide potential drunk drivers with information that will make it easier for them to avoid driving while dangerously or illegally drunk. Such infor- mation might include simple rules of thumb for determining how many drinks a person of given body weight can drink on a full and an empty stomach before reaching 0.10 percent BAC (e.g., simple sobriety tests one might give oneself to decide whether or not to drive, or socially and economically acceptable alternatives to driving when one realizes one has had too much to drink). Of course, such a campaign would hinge on the existence of such rules of thumb, tests, and alternatives. Attempts to achieve general deterrence of drunk driving through pub- lic information and education have generally employed the first two avenues, describing the risks of drunken driving and trying to form attitudes against it. While there have been many sucl, campaigns, a relatively small number have been subjected to scientific evaluation of their impact on drinking-driving behavior (Jones and Joscelyn 1978, Organisation for Economic Co-operation and Development 1978, Wilde 1971~. Of these, the one that came nearest to success was a campaign conducted in Edmonton, Canada, during December 1972 (Organisation for Economic Co-operation and Development 1978, p. 88~: "In this campaign evaluation a control city (Calgary) was used and initial results suggested a trend towards reduced blood alcohol levels among Edmon- ton drivers apparently as a result of the campaign." There is no evidence that the Edmonton campaign reduced the number of traffic accidents. Conclusion In conclusion, general deterrence of drunk driving does seem possible if a high perceived risk of arrest can be sustained. Severe punishment does not appear as promising as increased arrest risk for achieving gen- eral deterrence. Public information and education campaigns that pro- vide information useful to those who wish to avoid driving while dan- gerously or illegally drunk, without radically changing their drinking or driving behavior, may also be useful.
352 REDUCTION OF RECIDIVISM REED Maximum Potential Savings The potential reduction in traffic accidents obtainable by reducing DWI recidivism is sharply limited by the small number of persons with pre- vious DWI arrests among drivers involved in accidents while driving with a positive BAC level. Sterling-Smith (1976, pp. 111, 135) reports that of drivers responsible for fatal accidents in the Boston area during the early 1970s, 4 percent had a previous DWI arrest and 39 percent had a BAC level exceeding 0.05 percent at the time of the accident. Thus, even if all drivers responsible for fatal accidents with a previous DWI arrest had a BAC exceeding O.Q5 percent at the time of their accident, only 10 percent (i.e.? 4 percent/39 percent) of drunk drivers responsible for fatal crashes would have had a previous DWI arrest. Hurst (1973) has suggested that more experienced drinking drivers? when driving with a positive BAC level, may drive in a slow, cautious, but erratic manner that reduces their chances of serious accident com- pared with other drivers at the same BAC level. This mariner of driving would probably increase the chance of less serious accidents as well as arrest. Since drunk drivers with previous DWI arrests are more likely to be experienced drunk drivers than those without, we would expect drunk drivers with previous DWI arrests to be more heavily represented among drivers in less serious accidents than in fatal accidents. This expectation is borne out in data reported by Waller (U.S. De- partment of Transportation 1968, p. 67~? that of male drivers in crashes involving alcohol or hit-and-run, 20 percent had one or more previous arrest for DWI. Based on the Sterling-Smith and Walter findings, I estimate that drivers with previous DWI arrests comprise 10 percent of all alcohol-influenced drivers in fatal accidents, 15 percent in injury accidents' and 20 percent in property-damage-only accidents. Multiplying these estimates by my figures from Table 2 for the per- centage of accidents that would be prevented if all drunk driving was eliminated, and the resulting cost savings in 1977, we arrive at estimates of the savings if all drunk driving by persons with previous DWI arrests was eliminated- that is, the savings from a "perfect' countermeasure reducing recidivism. The results are shown in Table 4. Of course if the risk of arrest for drunk driving increased, so would the percentage of accident-involved drunk drivers with previous DWI arrests. Thus, in- creased risk of arrest would raise the potential savings from reducing DWI recidivism.
Reducing tile Costs of Drinking and Driving TABLE 4 Expected Reduction in Motor Vehicle Traffic Accidents and Costs as a Result of Preventing All Drunk Driving by Persons with Previous Arrests for Driving While Intoxicated :53 Type of Accident, Place and Time Expected Reduction in United States, 1977 Fatal, Vennont, 1967-1968 2.4~o 1,188 lives Injury, Huntsville, 19701975 2.4% 45,600 injuries Injury, Grand Rapids, 1962-1963 1.2~o 22,800 injuries Property damage, Grand Rapids, 1962-1963 1.1% $171 million Effectiveness of Treatments We are still left with the question of what is the best way to treat those arrested for DWI. Possible treatments fall into two categories. The first is punitive, involving treatments such as fines, imprisonment, license suspension and revocation, and license restriction (e.g., to allow driving only to and from work). Many "punitive" treatments are also prophy- lactic, in that they temporarily or permanently restrict the subject's opportunity to drive drunk again. The second is educational and ther- apeutic, including such treatments as drinking-driver schools, group therapy, and treatment for general alcohol abuse. In general, educational and therapeutic treatment is more expensive than punitive treatment (an exception being long-term imprisonment) but not necessarily more effective in preventing accidents. A review of relevant literature (Preusser et al. 1976, Jones and Joscelyn 1978, pp. 56-63, Organisation for Economic Co-operation and Development 1978, pp. 91-96, Nichols et al. 1978, Comptroller General of the U.S. 1979, pp. 4-34, U.S. Department of Transportation 1979a,b) yields the fol- lowing observations: · No credible evaluation has shown that any educational or thera- peutic treatment reduces future accidents of a person arrested for DWI more than traditional punitive treatment does. However, at least two studies of intensive treatment for general alcohol abuse showed a decline in the future incidence of accidents and rearrests combined (Organi- sation for Economic Co-operation and Development 1978, pp. 92, 95~. · Some evaluations have reported a decrease in the DWI rearrest
354 REED rate due to educational or therapeutic treatment, but such reports appear to vary inversely with the scientific rigor of the evaluation. Even when an improvement is reported, it is small. Aggregate data from the ASAP program indicate that for DWI arrestees classified as "social drinkers," the group found to be most responsive to educational and therapeutic treatments, such treatments are associated with a small (less than 15 percent) increase in the number of persons not rearrested for DWI within 3 years (Nichols et al. 1978, p. 180~. · While DWI arrestees classified as "problem drinkers" (including "alcoholics") have been shown to be less responsive than "social drink- ers" to educational and therapeutic treatment in general, they appear to be more responsive to more personalized and interactive treatment than to more formal treatment, and more responsive to programs clas- sified as therapeutic than those classified as educational. These differ- ences are not apparent when treating "social drinkers" (Nichols et al. 1978, pp. 183-185~. A poor record of past performance does not preclude future success, but the burden of proof seems to rest with advocates of a particular educational or therapeutic treatment program to show reason to believe that such a program will reduce recidivism more sharply than the cheaper punitive approach. Although an analysis of the treatment of general alcohol abuse is outside the scope of this paper, it should be noted that court referral of DWI offenders has become an important case-finding mechanism for alcoholism treatment programs. Persons thus referred tend to be younger, lighter drinkers, and to have suffered less disruption of their lives from alcohol abuse than others entering alcoholism treatment (Chatham and Batt 1979~. THIRI)-PARTY INTERVENTION The potential of this approach obviously hinges on what fraction of drunk drivers involved in accidents were drinking and driving in the presence of others before their accidents. Unfortunately, this infor- mation does not seem to be available, although data concerning the predriving drinking venue of DWI arrestees may be available.6 It seems reasonable to assume, however, that a large fraction of drunk drivers, h In the process of its 'iDUI Protect described in the text the California Department of Alcoholic Beverage Control collected data on where persons had been drinking who were arrested for driving under the influence of alcohol.
Reducing the Costs of Drinking and Driving 355 perhaps a majority, were drinking in the presence of other persons before driving. Servers and fellow guests or patrons can take various steps to reduce drunk driving, such as: · Make it less convenient or less socially acceptable for a guest or patron to drink to intoxication. · Suggest that intoxicated guests or patrons wait to sober up before driving or have a friend or taxi take them home. · Physically restrain or report to police an intoxicated guest or patron who insists on driving. All of these steps impose some costs on the third party: reduction in profit or apparent hospitality, the expense or inconvenience of arranging alternative transportation or lodging for the inebriate, or the unpleas- antness of telling a person that he or she is for the moment incompetent to drive. The problem, then, is how to convince third parties to bear these costs. As mentioned above, public information and education campaigns have been used to try to increase third-party intervention. These cam- paigns face the same difficulties as those attempting general deterrence; no truthful information that could be provided is likely to have much impact on a third party's perception of the risk inherent in drunk driving by others, since present perceptions appear to be fairly accurate. More- over, a media campaign may not have sufficient persuasive force to alter social behavior that is reinforced by groups important to the individual. As for its use in general deterrence, however, the use of public infor- mation and education for third-party intervention is unproven rather than discredited. The other way to convince third parties to intervene in potential drunk-driving situations is to impose legal liability on them. Such liability may be imposed by statute (referred to as a dramshop law) or by court interpretation of common law. Mosher (1979, pp. 6-8) describes the present situation: Today there are eighteen state dram shop acts. A typical statute provides that a commercial seller of alcoholic beverages will be found liable for injuries caused by his or her patrons if the server sold or gave alcoholic beverages to the patron in violation of the law. A violation occurs if the patron is a minor, habitual drunkard, or someone "already" or "obviously" intoxicated when served. . . . Because most of these laws were passed before Prohibition, many are now outdated and not relevant to current social problems.... The habitual drunkard provisions are now largely ignored because of the difficulty and potential con-
356 REED stitutional problems involved in identifying those who can be considered "ha- bitual drunkards." . . . Courts in ten states without dram shop acts, five states with such acts, and the District of Columbia have imposed civil liability on commercial servers of alcoholic beverages by court decision . . . based on the server's alleged negligence. There is variation among states as to whether the drunk driver can sue a third party who contributed to his intoxication (Mosher 1979, p. 7~. In general, liability is imposed on "social hosts," those not in the business of serving alcohol, only when an underaged person is served, not when an "obviously intoxicated" person is served. Court decisions in Iowa and California that social hosts were liable if they served "obviously intoxicated" guests were quickly followed by legislation in each state overturning the decision (Mosher 1979, pp. 12-14~. In another case, a California court decided that a person who merely encourages another to drink without furnishing alcohol is not liable (p. 19~. One would hope that third-party liability would cause those liable, primarily commercial servers, to take steps to prevent drunk driving by patrons. Unfortunately, the criteria by which liability is judged do not encourage servers to take precautions. A server is considered liable if he or she served an underaged or "obviously intoxicated" person, and if that person subsequently did damage. To take reasonable precautions to avoid serving such persons or to prevent those served from doing damage is not considered a valid defense (Mosher 1979, pp. 22-23~. If a single patron or guest leaves and does damage and if a court decides post hoc that he or she was "obviously intoxicated" when served, then liability is determined. Since there is no standard of practice that, if adhered to, will absolve the server of responsibility, servers tend to view dramshop liability as a random risk, and insure against it rather than altering their serving practices (Mosher 1979, pp. 23-25~. If there were accepted standards of practice for servers of alcohol, and if following these practices absolved the server of liability even if a patron "slipped through," drove drunk, and had an accident, then presumably servers would follow these practices to protect themselves and avoid high insurance costs. (Insurance premiums increased 500 per- cent to 1,000 percent for commercial servers in California in the wake of a court decision imposing liability on them. Insurance rates for rel- atively small chains of on-premise sales reached $100,000 per year [Mosher 1979, p. 24~.) In addition to liability for the actions of intoxicated patrons, the mere serving of an intoxicated person by a commercial server is in violation of the alcoholic beverage control (ABC) laws of most states. Unfortu- nately, state ABC departments have traditionally concentrated much more effort on ensuring the operation of an orderly industry with a low
Redlucing the Costs of Drinking and Driving 357 level of competition than on preventing alcohol-related problems such as drunk driving (Matlins 19764. An exception is the "DUI (Driving Under the Influence) Project" of the California Department of Alcoholic Beverage Control (Mosher and Wallack 1979~. In this experimental program drivers arrested for drunk driving were asked where they had been drinking. On-premise retailers who were twice identified in this way were offered free training for their personnel by the Department of ABC on methods of detecting intoxi- cated patrons and curtailing their consumption. It seems that the concern over dramshop liability was largely responsible for the good cooperation the Department of ABC received from retailers during this project. There was no evaluation of the project's impact on drunken driving or accidents. Nonetheless, it is significant as an example of involvement of a state ABC department in drunk-driving countermeasures, and as an instance of a government agency developing and recommending standards of practice for servers of alcohol to avoid intoxication and subsequent drunk driving by patrons. MINIMUM DRINKING AGE If people are prevented from drinking, then they are also prevented from driving drunk. A return to prohibition would be politically un- feasible even if it were desirable, but persons under a given age are routinely prohibited from purchasing or consuming alcohol. Throughout the United States, the minimum drinking age is set within the range from 18 to 21 years. It is probably unrealistic to consider setting a minimum drinking age outside this range, but the question remains of what value within the range is optimal. It is clear from several studies that when the drinking age is lowered from 21 or 20 to 18, the number of accidents involving 18-, 19-, and 20- year-old drivers increases (Organisation for Economic Co-operation and Development 197S, pp. 96-98, Comptroller General of the U.S. 1979, pp. 43-45, Haddon 1979, pp. 56-57, Scotch 1979, pp. 2-4~. Various studies have found the percentage increase to range from undetectable to 26 percent. The fact that prohibiting 18- to 20-year-olds from drinking reduces their accident involvement does not in itself make a convincing argument for setting the drinking age at 21. After all, prohibiting persons of any age-group from drinking would probably reduce their accident involve- ment. On what basis can we decide that persons who are old enough to drive, vote, and enter into contracts may not have the same access to alcohol as all other adults? A possible justification is that accident risk rises more quickly with
358 REED BAC level for drivers under 21 than for any other age-group (Jones and Joscelyn 197S, pp. 31-33~. It is unclear, however, to what degree this is merely because younger drivers tend to be less experienced at drinking and drinking and driving. Those who drink more often are at less risk at ally given BAC level. To the degree that the association between age and sensitivity to BAC is due to lack of drinking experience, raising the drinking age will merely transfer high accident risk from drivers under 20 to those recently turned 21. SCREENING A strategy that has received little attention is screening the population of drivers for those most likely to drive drunk and targeting counter- measures to them as individuals. An example of this strategy is a program that had been planned by federal and District of Columbia officials in which every driver applying for a renewal of his or her driver's license (and, presumably, an initial license) would be given a written test to determine whether she or he is, or is likely to become, a problem drinker. Those drivers so identified would be required to attend a pro- gram on alcohol education before they would be issued unrestricted drivers' licenses. One consultant involved in the project compared the measure to the current requirement that diabetics, epileptics, and other persons whose driving could be impaired by recurrent illness must certify that they are under proper medical care and control before being issued licenses. As a pilot study for the contemplated project, drivers renewing their licenses in the District of Columbia during 1976 were asked to volun- tarily, and anonymously, take part of a widely used test for current or prospective alcohol abuse. The test took less than 15 minutes to complete and consisted of a series of yes/no and true/false questions. Many con- sidered the questions, some of which dealt with the driver's income, relationship with spouse, and arrest and drinking-driving history? to be too personal and inappropriate for a motor vehicle licensing agency to ask. Despite the fact that the test had been given on a voluntary and anonymous basis, press coverage, citizens' complaints, and protests by the American Civil Liberties Union led the mayor to suspend the project for further study and eventually to order the program aborted and all collected data destroyed. (The above information was culled from the Washington Post for August 5, 1976, August 7, 1976, August 31, 1976, December 22, 1976.) This experience does not bode well for countermeasures involving mass screenings. There seem to be two basic problems.
Reducing the Costs of Drinking and Driving 359 · The screening device. The test or procedure used for screening must use only information that is considered proper for licensing au- thorities to examine. Information in this class might include convictions for drunken driving and other alcohol-related offenses, and perhaps whether the driver has ever been treated for alcohol abuse. The screen- ing device must produce a low level of false positive errors in order not to inconvenience or stigmatize persons without drinking problems. · The treatment of persons identified by the screening. Treatment is largely dependent on what the screening device tests for. If potential drunk drivers are identified, then some sort of alcohol education or other preventive measure may work. If actual drinking drivers are iden- tified, then the problem is the same as that of reducing recidivism (spe- cific deterrence). A program in North Carolina screened driver license records to iden- tify "habitual offenders" based on past traffic convictions (Li and Wailer 1976~. Many of the "habitual offenders" were drinking drivers. Despite a law authorizing S-year license revocations for habitual offenders, 62 percent of the referrals from the screening program were never acted on by prosecutors. The screening program was widely viewed as super- fluous, because there was opportunity to impose similar sanctions on "habitual offenders" when they were brought to court for a particular offense. This may be a generic weakness of screening programs based on public record information. DETECTION DEVICES IN VEHICLES The suggestion has been made that cards be equipped with devices that will detect an intoxicated driver and either prevent the car from starting or make it very conspicuous on the road, for example, by automatic flashing headlights. Such a device could be installed in all cars or in only those driven by persons who seem likely to drive after drinking (e.g., persons with previous DWI convictions). Of course, any such device could be bypassed: a driver alone or with the help of a mechanic could remove the device, render it inoperative, or even install a switch to reactivate it if the car was subject to periodic . . Inspection. Of the two types of detectors that have been developed, either are to some degree capable of being circumvented by having a sober com- panion take the "test" for the drinking driver. One type of detector is a breath alcohol analyzer; the other is a skill tester, such as one requiring the driver to punch into a keyboard a series of random numbers that are briefly displayed on a screen.
360 REED Although it is clear that any of the detection devices so far suggested can be defeated, they may still be of use since they require the driver to admit to himself or herself and to anyone else whose aid has been enlisted, that he or she is too drunk to drive. It is not known how much exposure would be reduced if potential drunk drivers and those around them were given unambiguous and immediate evidence that they were incapacitated. More advanced detectors than are currently available, such as those that would continuously "sniff" the air around the driver's head for alcohol, or that would continuously monitor the driver's behavior for such signs of intoxication as oversteering, would eliminate the problem of someone's starting a drunk's car for him or her, although they would still be susceptible to bypass. The widespread installation of detection devices in vehicles may meet hostile public reaction, since even those who never wish to drive drunk are likely to oppose the inconvenience as well as the added expense. The inconvenience and expense would be more easily justified if de- tectors were installed only in the cars of persons with previous DWI convictions. One would expect such persons to have a greater likelihood of driving drunk in the future than do drivers in general and, indeed, empirical evidence suggests that this expectation is correct (Jones and Joscelyn 197S, p. 37~. ALTERNATIVE TRANSPORTATION To have an intoxicated person ride public transportation is safer for himself or herself and, of course, for others. It therefore seems promising to provide public transportation as an alternative to drinking and driving at times and places with a high concentration of drinking. For example, it is reported that the alcoholic beverage industry supplies free mass transit in Toronto on New Year's Eve. A large part of Washington, D.C., is closed to traffic on the night of the Fourth of July, and expanded bus and subway service is provided free of charge (although this is probably targeted as much at relieving traffic congestion as preventing drunk driving). There do not seem to be any evaluations of alternative transportation programs for drunken-driving countermeasures, therefore little can be said regarding this strategy's effectiveness and efficiency. FINDINGS AND RECOMMENDATIONS While our knowledge regarding the ways in which the amount of drunk driving can be reduced is far from complete, it does lead to some con- clusions that may be useful to the policy maker.
Reducing the Costs of Drinking and Driving General Deterrence 361 There is good evidence that if drivers in general perceive a high risk of being arrested if they drive drunk they will be deterred from doing so, and alcohol-related traffic accidents will decrease substantially. It is currently unknown how high the risk of arrest must be maintained to achieve deterrence or how much it would cost to maintain such risk. Carefully designed and evaluated experimental countermeasure pro- grams should be executed in which steps are taken to increase the risk of arrest for drunk drivers, the risk of arrest is measured, and the impact on drinking-driving behavior and accidents is assessed. There is no convincing evidence that severe punishments deter drunk driving in the absence of high risk of arrest. A massive effort to start changing social attitudes about drinking and driving, as urged by a recent report by the General Accounting Office to be the major thrust of federal drinking-driving countermeasure ef- forts, would be a poor allocation of resources. Public information and education campaigns explaining the risks of drunk driving are unlikely to affect behavior, since the public at large has a fairly accurate per- ception of these risks already. Campaigns aimed at altering individual norms and attitudes concerning drinking and driving are unlikely to have much impact, since such norms are set and constantly reinforced by social groups with which individuals identify. If, however, information is available that would help individuals avoid driving when dangerously or illegally drunk without radically changing their values and social behavior, then disseminating such information would be a useful coun- termeasure. Red ucing Recid ivism (Specific DeterrenceJ Since only a small number of drivers involved in alcohol-related acci- dents have previous arrests for drunk driving, the potential savings from reducing recidivism is sharply limited. Even if all persons with drunk- driving arrests were prevented from ever combining drinking and driving again, the reduction in motor vehicle traffic accidents would be only about 1-3 percent, although absolute cost savings would not be trivial. Increasing the risk of arrest for drunk driving would increase the po- tential savings from reducing recidivism. Educational and therapeutic treatments for arrested drunk drivers, such as the drinking driver schools operating in many states, rarely cause a reduction in recidivism compared with traditional punitive measures such as fines. The burden of proof should rest with the advocates of a particular educational or therapeutic treatment program to show that
362 REED such a program will reduce recidivism more sharply than the punitive approach, which has lower costs. Court referrals of drunk-driving offenders deemed to be problem drinkers or alcoholics has become a significant case-finding mechanism for programs of alcohol abuse treatment. Third-Part;y Intervention Servers of alcohol and other persons can intervene to prevent an indi- vidual from becoming intoxicated and driving. Such actions impose costs on the intervener, so finding ways to motivate intervention is important. Public information and education campaigns are likely to be no more effective in increasing third-party intervention than in bringing about general deterrence. Dramshop laws and court decisions to the same effect impose liability on commercial servers of alcohol for damage done by patrons who were underage or served while "obviously intoxicated." Under current prac- tice, servers are held liable regardless of whether they took reasonable precautions to avoid drunk driving by patrons. For this reason, servers tend to insure themselves against dramshop liability (and engage in political action against it) rather than altering their serving practices to reduce the risk. Standards of practice for servers that would reduce the risk of drunk driving should be developed and disseminated. Courts and legislatures should be encouraged to absolve servers who follow these standards of liability for damage done by patrons who drive drunk de- spite the server's efforts. Drinking Age The minimum drinking age in all states is currently between 18 and 21, and it does not seem feasible to adopt a drinking age outside this range. When the drinking age is lowered from 21 to IS, the accident involve- ment of 18-, 19-, and 20-year-old drivers increases. The same effect would probably occur to any age-group that was prohibited from drink- ing, so the case is not clear for setting the drinking age at 21. Drivers under 21 are more sensitive in their accident risk to BAC than are other drivers, but this may be merely because they are inexperienced drinkers. If so, then raising the drinking age would merely transfer increased accident risk from drivers under 21 to those just over 21. There is at present no compelling case for denying persons between the ages of 18 and 21 the same access to alcohol as all other persons who have attained . . maJorlty.
Reducing the Costs of Drinking and Driving Screening 363 It may be possible to screen the driving population for those most likely to drive drunk and expose these people to preventive treatments, but this approach has yet to be shown workable. An attempt in Washington, D.C., failed, largely because the screening test was viewed as an invasion of privacy. Although it may be better developed in the future, the screening approach seems to have little potential in the near future. Detection Devices in Vehicles It is technologically possible to install in a car a device that will prevent an intoxicated person from starting the car. Such devices may be cir- cumvented, but they may still have significant effectiveness in reducing drunk driving. The cost and inconvenience of having such devices on all cars may arouse public opposition and indeed may not be warranted by their effectiveness as a countermeasure. The use of such devices could be tested on the cars of a sample of drivers convicted of drunk driving. Since such persons are presumably more likely to drive drunk in the future than is the average driver, the cost and inconvenience of the detection devices are more likely to be warranted in this application. Alternative Transportation Providing public transportation at times and in places in which drinking and drinking and driving are concentrated may in some cases be an effective and efficient countermeasure. No evaluation of this approach is currently available, but a test may be useful and not very expensive in an area with an existing mass transit system. REDUCING RISK PERVERSE INCENTIVES Reducing risk refers to lowering the expected cost, in term of deaths, injuries, and property damage, of each unit of drunk driving. A possible objection to such a strategy is that as drunk driving becomes safer, people will do more of it. The question involves estimating the "risk elasticity of drunken driv- ing." If a 1-percent decrease in the risk of drunk driving led to a 1- percent increase in the amount of drunk driving (i.e., if elasticity equals one), then our efforts to reduce risk would seem vain. The total costs
364 REED resulting from drunk driving would remain the same. Conceivably, the elasticity may be greater than one, which is to say that a decrease in risk would lead to a greater increase in exposure, so that total costs from drunk driving would increase. I would like to suggest that the elasticity is less than one; that when the adverse consequences of an act are both remote in probability and so serious that they are painful to contemplate, as is the possibility of a serious accident resulting from drunk driving, that a person will tend to evaluate the risk at less than its expected cost and will be insensitive to small changes in the expected cost. This would explain why drivers seemed no more effectively deterred from drunk driving by the threat of a jail sentence than of a license suspension in the Chicago experiment (see above). The probability of being subjected to either penalty was quite small, and both penalties were so serious that one would be tempted to think "that couldn't happen to me." If this speculation is accurate, then changes in the risk of drunken driving brought about by risk-reducing measures would not have a large impact on the amount of drunk driving and would result in a reduction of total costs resulting from drunk driving (net of the cost of bringing about the risk reduction). This speculation could be tested experimen- tally if the amount of drunk driving in an area was measured before and after a quick and significant reduction in the risk of drunken driving. GENERALLY APPLIED RISK REDUCTION Some risk reduction measures are applied to drivers in general. They may be differentially more (or less) effective in lowering the risk of drivers with elevated BAC levels, but implementing the measures does not require knowing which drivers are likely to be impaired. Passive restraint systems, for instance (such as air bags or automatic seat belts), would protect vehicle occupants regardless of alcohol in- volvement in a crash, but they would be differentially effective in pro- tecting drunk drivers involved in accidents since they are less likely to use conventional seat belts than are drivers involved in accidents in general (Sterling-Smith 1976, p. 160~. The same is true of other attempts to make vehicles in general more crashworthy. Other changes in the driving environment would reduce the probability of accident or the probable severity of accidents that do occur for all drivers while having a differentially greater effect on drinking drivers. For example, the ability to divide attention between tasks has been found to be one of the driving-related skills degraded first and most severely as BAC in-
Reducing the Costs of Drinking and Driving 365 creases (U.S. Department of Transportation 1968, pp. 42-52~. There- fore, speed governors in cars, redesigned road markings, and other changes in the driving environment that reduce the driver's need to frequently shift attention would probably result in greater risk reduction among drinking drivers than drivers in general. Some generally applied risk reduction measures would benefit only those persons with elevated BAC levels. Haddon and Baker (1978, p. 16) point out that "injured people are rarely tested for alcohol in emer- gency rooms although symptoms, diagnoses, response to drugs and anesthesia, and even prognosis may be influenced by alcohol." Informal consultation with physicians experienced in emergency room situations suggests that physicians do not routinely test accident victims for alcohol, relying on cues such as breath odor, drunken behavior, and unac- counted-for unconsciousness to warn them of possible alcohol involve- ment. William Haddon, M.D., of the Insurance Institute for Highway Safety, has suggested that medical personnel may be reluctant to test for alcohol in part because doing so might tend to involve them in litigation concerning the accident in which the patient was injured. It is certainly not clear prima facie whether the incremental improve- ment in medical care resulting from more frequent tests for alcohol would be worth the expense of such testing. It might be found that testing some subgroups of accident victims, such as those injured in nighttime traffic accidents, is cost-effective. All measures to reduce the risks of drunken driving (as opposed to amount of drunken driving)even measures that offer no protection to persons with zero BAC levels should be evaluated and assigned priority In relation to all proposed measures to reduce the risk of driving in general. In a world of limited resources there is no defense for spend- ing a dollar to reduce alcohol-related accidents if the same expenditure would be more effective if applied to reducing motor vehicle traffic accidents in general. Similarly, if the lives of drinking drivers should be weighted no less heavily than those of innocent victims when selecting countermeasures, then a marginal dollar should be devoted to alcohol- specific risk reduction if this produces the greatest expected savings in accident costs (lives, injuries, and property damage). It is important, therefore, that government agencies choosing among motor vehicle traffic safety measures evaluate their benefits in a way that recognizes drunk drivers are a minority on the road and that they have differential sensitivity to some safety measures. This will promote the efficient mix of alcohol-specific and nonalcohol-specific risk reduc- tion.
366 SPECIFICALLY APPLIED RISK REDUCTION REED Some measures to reduce the risk of drunken driving may be uneco- nomical or impractical to apply to drivers in general, but cost-effective and practical when applied specifically to drivers with a higher than normal probability of driving with elevated BAC levels. Some modifications to improve a vehicle's crashworthiness or ease of driving, as mentioned in the previous section, may be cost-effective only when applied to the vehicles of persons with previous drunk-driving arrests, persons requesting such safety devices for their cars, or persons willing to buy such protection on the free market. In the case of specifically applied risk reduction the problem of po- litical acceptability may be greatest. For instance, it is known that drow- siness, one of the obvious effects of drinking, impairs driving ability, yet public information and education campaigns from government and private sources consistently omit such suggestions as taking caffeine, driving with the window open, or playing the radio when driving after drinking. (Although it is frequently and accurately pointed out that coffee does not reverse the intoxicating effects of alcohol.) Presumably, such suggestions are omitted because they could be perceived as en- couraging drunk driving by lowering its expected cost. There does not appear to be empirical evidence as to whether a driver with an elevated BAC level has less risk of accident with or without antidrowsiness meas- ures, and the answer is not clear a priori (e.g., is a more awake drunk driver also more recklessly. Such questions are not even asked when the problem of perverse incentives is viewed as a moral issue rather than an issue of effectiveness. FINDINGS AND RECOMMENDATIONS Reducing the risk associated with drunken driving would tend to increase the amount of drunken driving that is done. I speculate that the "risk elasticity of drunken driving" is less than one, meaning that a decrease in risk is likely to bring about a smaller increase in exposure, resulting in a net reduction in accidents. Risk-reducing measures that affect drinking drivers by the same mech- anism that they affect drivers in general are best considered in the context of general traffic safety. Those concerned with alcohol-related problems should check that the procedures used by traffic safety au- thorities to select countermeasures accurately take into account differ- ential impacts on drinking drivers. (For example drinking drivers use seat belts less often than drivers in general.)
Reducing the Costs of Drinking and Driving To the extent that general traffic safety measures are successful, they will reduce the accident reduction attributable to drinking-driving coun- termeasures. The extent of the drinking-driver problem should be pe- riodically reviewed to determine if extensive countermeasures are still warranted. Research should be performed to determine whether it would be cost- effective for emergency medical personnel to test traffic accident victims for alcohol. Alcohol affects particular skills important to driving. It may be pos- sible to redesign portions of the driving environment to decrease the impact on accident risk of degradation of these skills. Cars driven by persons likely to drive drunk, such as those with pre- vious DWI convictions, could be held to higher standards of crashwor- thiness than cars in general. This might, however, tend to make drivers of such cars overconfident and be counterproductive, and public reaction may be hostile. 367 GOVERNMENT ACTION TOWARD DRINKING AND DRIVING In spite of the large reduction in deaths, injuries, and property damage that could be achieved by effective drinking-driving countermeasures, we have no technology to bring about these savings. I have demonstrated above that a consideration of possible countermeasures raises more questions than it answers. In the case of risk-reducing countermeasures, there is unfortunately little experience to draw on. There have been many applications of exposure-reducing countermeasures, yet despite this experience we have not developed any dependable and effective techniques. If our ability to prevent losses from drunken driving is ever to improve, we must begin to learn from experience. INSTITUTIONAL BIAS AGAINST LEARNING Cameron (1978, p. 11) has observed that: Only a small proportion of drinking-driving programs in the U.S. have ever been subjected to a scientific evaluation of their effectiveness in reducing al- cohol-traffic problems. In fact, much of what is known about the effectiveness of some types of drinking-driving countermeasures is based primarily on data from other countries. An example of evaluation problems is the Alcohol Safety Action Project (ASAP) program. The program consisted of 35 local ASAPs' each ap-
368 REED proximately 3~/: years in duration, funded by the U.S. Department of Transportation between 1969 and 1975 at a cost to the federal govern- ment exceeding $88 million (U.S. Department of Transportation 1979a,b). Each ASAP attempted to integrate and improve enforcement, prosecution, screening, and treatment countermeasures so as to reduce drunken driving and associated accidents in its geographic area. The design of the ASAP program did not allow for evaluation of its effectiveness as a drinking-driving countermeasure. Zimring's critique (1978) and the Department of Transportation's reports on the Program (U.S. Department of Transportation 1979a,b) reveal several important flaws: · Noncomparable sites. The original eight grantees included four cities, one "twin city" site, two counties, and the state of Wisconsin. · Inadequate control sites. Control sites for comparison with the ASAP sites were not selected until the projects had ended operation. This delay restricted potential control sites to the relatively few localities that happened to have kept sufficient accident records for comparison with ASAPs. · Proliferation instead of replication. The program expanded to 35 projects before the initial 8 had been completed and analyzed, therefore preventing evaluation problems from being detected in time to be cor- rected in the later projects. · Overaggregated evaluation. Evaluation focused on the change in accident occurrence at each ASAP site during the entire operational period at that site, even though each project used several types of coun- termeasures and many changes occurred in each project's countermea- sure programs during its operational period. At best, each evaluation could have determined the efficacy of focusing money and attention on drinking and driving; it did not have the potential to determine the efficacy of particular countermeasures. None of the above is to denigrate the skillfully prepared final reports on ASAP (U.S. Department of Transportation 1979a,b), but these were obviously post hoc efforts to scavenge findings from a program not well designed to supply them. Exceptions to the generally poor experimental design associated with ASAP include the Short Term Rehabilitation study (Nichols et al. 1978) and a well-designed experimental evaluation of a "drunk driver school" at the Nassau County, New York, ASAP (Preusser et al. 1976~. The lack of adequate evaluation is not confined to the efforts of the
Reducing the Costs of Drinking and Driving 369 U.S. Department of Transportation. During the early 1970s the National Institute on Alcohol Abuse and Alcoholism (NIAAA) funded 18 prob- lem drinking driver programs (PDDPs) to operate in conjunction with ASAPs. Stanford Research Institute was contracted to evaluate them and released its final report in 1975 (Eagleston et al. 1975~. Although the 131-page document reflects considerable work and ex- pense, it is of little use in determining whether PDDP, or any compo- nents of it, brought about improvement in the persons treated. The paper states (p. II-6: It is apparent that PDDP treatment and rehabilitation does affect [sic] a positive change on client drinking patterns and behavior as measured in various ways at intake and six months after intake. This is accomplished at a relatively low cost per client $153 on the average. As a result we recommend that these programs be continued. Even assuming that the measures at intake and 6 months later are entirely adequate, the report's data do not adequately support its con- clusion. First, without a control group, we do not know from the report whether the programs' clients would have shown just as much or more improvement in the absence of treatment. There is evidence that drink- ing problems are often transitory and exhibit spontaneous remission in the absence of treatment (Cahalan and Roizen 1974~. Second, the report does not account for or even mention distortion of the data through selection by potential clients and by program personnel of program entrants. Only 77.2 percent of clients making "initial contact" with a PDDP actually entered treatment (Eagleston et al. 1975, pp. V-5, V- 6~. Even if there had been a control group, superior progress among those in treatment might be a result of selection rather than of treatment. What can account for the persistent pattern of neglect of the most basic precepts of experimental design when planning and evaluating government drinking-driving programs? The answer, I believe, is that the persons and organizations with influence over these programs view them not as research, but as service provision. The programs are treated as if they were applying well-developed technology to solving a problem (I use the term "service" here in a broad sense to include arresting drunk drivers, repairing roads, etc). From the perspective of service provision, the program traits we have noted are predictable and expected and in many cases represent good management. If the purpose of a program is to provide service, then why spend money establishing control groups or collecting baseline data? Why wait until one project is evaluated before starting the next? These
370 REED efforts would reduce the amount of service one could provide. Of course, even a service provider sees the need for project evaluation, but the evaluation required for such purposes is a management and performance audit rather than a scientific investigation. If the technology has been assumed sound, then why question it? The political pressure on government agencies is no doubt to do something about drunken driving rather than to learn something about it. There is much evidence that agencies are quite responsive to this pressure. Remember that ASAP stood for Alcohol Safety Action Pro- ject. The ASAPs, touted as "demonstration projects" to show what could be done and how to do it, resulted in a set of handbooks for state and local governments on how to run an ASAP-type program, but with no assurance that this is a good way to reduce drinking-driving accidents (Hawkins et al. 1976, U.S. Department of Transportation 1979b). The problem drinking driver program "evaluation" is probably all a service provider could want in terms of reviewing the organization, manage- ment, and operation of these programs. It has little to offer those in- terested in whether PDDPs and programs like them are effective because it was never meant to address that question. RECOMMENDATION Unfortunately, we do not know how to prevent drinking-driving acci- dents and their related costs in a dependable and cost-efficient manner. It is therefore counterproductive to run government programs relating to drunken driving as if the primary purpose was service provision. Persons concerned with research and experimental design should work with those concerned with service provision and program management from the earliest planning and budgeting stages of drinking-driving coun- termeasure programs. Federal agencies sponsoring such programs should view the development and rigorous testing of the countermeasure being used as a goal at least coequal to the application of the counter- measure in an attempt to reduce drinking-driving accident costs. Pro- grams should not be termed "demonstration projects" unless they are indeed demonstrating a countermeasure that the agency has good reason to believe will be effective. Such recommendations will doubtlessly evoke protests that resources are being diverted from saving lives to performing research. But if our goal is immediate saving of lives then we are investing our resources poorly. The U.S. Department of Transportation (1979a~b) estimates that the ASAP program saved 506 lives at a cost of $156~306 each. I think a fairer estimate is that 425 lives were saved at a cost on the order
Reducing the Costs of Drinking and Driving 371 of $300,000 each.7 Using either set of estimates, it appears that more lives could have been saved by using the ASAP money elsewhere. As the U.S. Department of Transportation (1979a,b) points out, "The National Highway Safety Needs Report . . . ranks 37 countermeasures (by] cost per fatality forestalled.... The ASAP cost t$156,306] would rank between number 14- motorcycle lights-on practiceand number 15impact absorbing and roadway safety devices." Given our present level of technology for preventing drinking-driving accidents, additional expenditures seem warranted only if they promise to produce findings that will help us improve the technology and save more lives in the future, as well as contributing to current traffic safety. APPENDIX A: REVIEW OF EPIDEMIOLOGICAL STUDIES To my knowledge, the five investigations reviewed here comprise all controlled epidemiological studies of the risk of automobile-accident involvement (as opposed to causation) associated with various BAC levels for drivers in the United States. I examine the studies here solely to determine the relationship between BAC and accidents, although the studies are rich in other information. Each study is briefly analyzed. The results of my analysis are sum- marized in Table A-1. The "risk" figure is a simple Bayesian calculation of the risk of having an accident per unit of driving within a BAC interval, as explained in Appendix C. The variation among results of the studies judged methodologically adequate seems explicable by differences in location, time, and accident severity. In rural areas such as Vermont, the small number of accidents involving traffic congestion would make accidents due to gross driver error (such as a drinking driver might make) a more important part of the total accident picture, thus increasing the risk figures for high BAC intervals. Similarly, the lower road congestion and average driving speed of the early 1960s would lead to a more important role for alcohol in 7 The DOT figure of 506 lives saved is based on the sum of accident reduction at all ASAP sites that exhibited a statistically significant decrease in accidents. I think it is more informative to subtract from this estimate the sum of accident increase at the two ASAP sites that exhibited a statistically significant increase in accidents in order to balance gratuitous accident reductions at the sites exhibiting reductions: thus my figure of 425 lives saved. To estimate ASAP costs I deducted the portion of federal ASAP funds devoted to evaluation and then doubled the balance to roughly account for other federal funds. state and local expenditures, and expenditures by persons arrested for drunk driving. The resulting estimated cost for ASAP countermeasures is $141 million.
372 REED TABLE A-1 Epidemiological Studies of BAC and Risk of Accident Involvement Relative Risk Within BAC Intervals Description of Study <0.01 0.01~.049 0.05~.099 0.10 0.149 ~0.15 Evanston' Ill., 193~1938 Injury accidents Comparatively poor method- ology 1.00 3.82 2.90 12.73 53.92 Grand Rapids, Mich., 1962-1963 5.70 18.85 All accidents 1.00 0.91 1.52 Methodologically adequate 8.82 Injury accidents 1.00 0.92 1.86 Ill-matched control group 10.77 Damage-only accidents 1.00 0.94 1.53 Ill-matched control group 7.95 Huntsville, Ala., 197~1975 Injury accidents 1.00 1.34 2.02 2.73 13.42 Methodologically adequate New York, N.Y., 195~1960 Dnver-fatal accidents Inadequate sample size 1.00 0.82 1.27 3.21 39.73 Vermont, 1967-1968 Dnver-fatal accidents 1.00 1.02 3.27 Methodologically adequate 21.07 53.43 accidents than it had in the mid-1970s. This might account for the Grand Rapids study showing greater alcohol-related risk than the Hunstville study. The tables on the following pages show the derivation of relative risk figures from each study's data. Table columns labeled "Ratio" show the ratio of percent of all accident group observations within the BAC interval to percent of all control group observations within that interval. The column labeled "Risk" shows the values in the "Ratio" column multiplied by the constant necessary to make risk in the lowest BAC interval equal to one. EVANSTON Richard L. Holcomb (1938) Alcohol in relation to traffic accidents. Journal of the American Medical Association 111~12~: 1076-1085.
Reducing the Costs of Drinking and Driving 373 Case group was some accidents resulting in hospitalization, in and near Evanston, Ill., between Feburary 1, 1935, and February 1, 1938. Method of selection is not explained in report. Control group was vehicles stopped at eight locations in Evanston "which approximated the area in which the accidents of the first part of the study occurred." Samples were taken during the following periods during a week beginning Saturday, April 23, 1938: Saturday Sunday Monday Tuesday Wednesday Thursday Friday Saturday 0000 to 2400 0000 to 2400 0000 to 0600 and 1800 to 2400 0600 to 1800 0000 to 0600 and 1800 to 2400 0000 to 1800 0000 to 0600 and 1800 to 2400 0000 to 0200 Of the control group 1.35 percent refused the BAC test. It is not reported what fraction of the case group refused, but the report claims "rather good cooperation was obtained from the drivers examined. A representative cross section of all drivers involved in injury accidents was thus obtained" (p. 1077~. TABLE A-2 Evanston: Survey Results and Relative Risk BAC # Control To Control # Accident To Accident Ratio Risk <0.01 1,538.78 87.93 144.10 53.37 0.61 1.00 0.01~.049 100.98 5.77 36.26 13.43 2.33 3.82 0.05 0.099 77.35 4.42 21.14 7.83 1.77 2.90 0.10~).149 26.08 1.49 31.21 11.56 7.76 12.73 ~0.15 7.35 0.42 37.29 13.81 32.88 53.92 The selection of neither the case nor control group is explained in detail, and neither appears to have been selected with as much rigor as in more recent studies. Thus, the reliability of this study's results is questionable. GRAND RAPIDS R. F. Borkenstein, Crowther, R. F., Shumate, R. P., Ziel, W. B., and Zylman, R. (1974) The Role of the Drinking Driver in Traffic Accidents,
374 REED 2nd ea., Blutalkohol XI (Supplement 1):8-131. (1st ed. unpublished, Department of Police Administration, Indiana University, 1964.) Case group was all accidents in Grand Rapids, Michigan, between July 1, 1962, and June 30, 1963. Control group was four vehicles stopped at random at each of 2,000 time-place sites selected at random from sites of all reported accidents between May 1, 1959, and April 30, 1962. Control group sampled over same period as accident group. Of control group 2.18 percent and 4.25 percent of accident group refused the BAC test (p. 39~. Refusal rates were generally higher in demographic groups more prone to drunken driving (pp. 52-57~. The probable result is a significant but small bias toward underestimating the relative risk of driving at higher BAC levels. TABLE A-3 Grand Rapids: Survey Results and Relative Risk BAC # Control 5to Control # Accident Do Accident Ratio Risk <0.01 6,756 89.01 4,992 83.41 0.94 1.00 0.01~.049 589 7.76 406 6.71 0.86 0.91 0.05 0.099 187 2.46 210 3.51 1.43 1.52 0.10 0.149 44 0.58 186 3.11 5.36 5.70 ~0.15 14 0.18 191 3.19 17.72 18.85 In order to promote driver cooperation, the study was heavily pub- licized while observations were being made. Although Borkenstein claims that this publicity was insignificant as a drinking-driving coun- termeasure and therefore as a source of bias (p. 52), I suspect that it caused a small decrease in the frequency of drunken driving by moderate drinkers (who would have positive BAC levels below about 0.104. I cannot predict with any confidence its impact on the "risk" associated with various BAC levels. The study also presents the distributions across BAC categories of only those accidents that resulted in injury, including the 15 accidents that resulted in death, and of only those accidents that resulted in property damage. The study does not, however, show the distribution across BAC intervals of control group observations corre- sponding to these two severities of accidents. Thus, the risk figures presented in Tables A-4 and A-5 are based on case group observations for the severity of accident indicated and control group observations for all accidents.
Reducing the Costs of Drinking and Driving TABLE AM Injury Accidents: Survey Results and Relative Risk 375 BAC # Control Ho Control # Accident No Accident Ratio Risk <0.01 6,756 89.01 1,162 81.83 0.92 1.00 0.01-0.049 589 7.76 93 6.55 0.84 0.92 0.05-0.079 132 1.74 27 1.90 1.09 1.19 0.0~0. 109 76 1.00 47 3.31 3.31 3.61 ~0.11 37 0.49 91 6.41 13.08 14.62 I have interpolated these results into my standard BAC categories by assuming uniform density of observations within the interval 0.08-0.109 (There are insufficient data to show ~0.15 as a separate interval.) <0.01 6,756 89.01 1,162 81.83 0.92 1.00 0.01-0.049 589 7.76 93 6.55 0.84 0.92 0.05-0.099 187 2.46 58.33 4.1 1 1.67 1.86 ~0. 10 58 0.76 106.67 7.5 1 9.88 10.77 TABLE A-5 Damage-Only Accidents: Survey Results and Relative Risk BAC # Control % Control # Accident °%c Accident Ratio Risk <0.01 6,756 89.01 3,833 83.87 0.94 1.0() 0.01-0.049 589 7.76 315 6.89 0.89 0.94 0.05-0.079 132 1.74 105 2.30 1.32 1.4() 0.0~0. 109 76 1.00 85 1 .85 1 .85 1 .96 ~0. 1 1 37 0.49 232 5.08 10.37 1().99 I have interpolated these results into my standard categories as above: <0.01 6,756 89.01 3 Ss33 Ss3.87 0.94 1.()~) 0.01-0.049 589 7.76 315 6.89 ().89 ().94 0.05-0.099 187 2.46 16 1.67 3.54 1.44 1.53 ~0. 10 58 0.76 260.33 5.7() 7.50 7.95 HUNTSVILLE R. Farris, Malone, T. B., and Lilliefors, H. (1976) A Comparison of Alcohol Involvement in Exposed and Injured Drivers, Phases I and 11. National Highway Traffic Safety Administration technical report DOT HS-801 826. Washington, D.C.: U.S. Department of Transportation. Case group was automobile drivers in injury-causing accidents in
376 REED Huntsville, Alabama, between July 1974 and July 1975, including the six fatal accidents during that period. Control group was an unreported number of drivers (averaging 2.61) stopped at same place, time of day, day of week, and direction of travel as each of the last 314 (of a total of 615) observations in the case group. Control observations were taken within 30 days of the case observation being matched. Two percent of control group and three percent of case group refused the BAC test. The subgroup of case observations to which controls were matched did not show a significantly or systematically different distribution of BAC levels than the earlier, unmatched case data. I have therefore pooled all case data. TABLE AM Huntsville: Survey Results and Relative Risk BAC # Control % Control # Accident No Accident Ratio Risk <0.029 728 90.32 459 76.63 0.85 1.00 0.0~0.059 25 3.10 23 3.84 1.24 1.46 0.0~0.099 30 3.72 38 6.34 1.70 2.00 0.1(}0.149 17 2.11 29 4.84 2.29 2.69 ~0.15 6 0.74 50 8.35 11.28 13.27 I have interpolated these results into my standard BAC categories by allowing each of the report's categories to "steal" enough observations from the next lower category to preserve its (the higher category's) original observation density as it expands to become one of my cate- gones. <0.01 710.76 88.18 443.14 73.98 0.84 1.00 0.01~.049 34.55 4.29 29.12 4.86 1.13 1.34 0.05~.099 37.69 4.68 47.74 7.97 1.70 2.02 0.10 0.149 17 2.11 29 4.84 2.29 2.73 ~0.15 6 0.74 50 8.35 11.28 13.42 NEW YORK James R. McCarroll and William Haddon, A controlled study of fatal automobile accidents in New York City. Journal of Chronic Diseases XV:811-826. Case group was fatally injured drivers in New York City, exclusive of Staten Island, between June 1, 1959, and October 24, 1960.
Reducing the Costs of Drinking and Driving 3~17 Control group was six cars going in the same direction at same place, time of day, and day of week as each accident in case group. "All site visits were made in 1960, within a few weeks of the calender week of occurrence" (p. 812~. Of the control group 0.39 percent refused the BAC test. BAC test was performed by the municipal medical examiner on each member of case group. TABLE A-7 New York: Survey Results and Relative Risk BAC # Control No Control # Accident % Accident Ratio Risk 0 195 77.38 14 41.18 0.53 1.00 <0.02 14 5.56 0 0.00 0.00 0.00 0.02~.099 34 13.49 3 8.82 0.65 ~ 1.23 0.1~0.249 9 3.57 2 5.88 1.65 3.12 0.25 0.399 0 0.00 15 44.12 I have interpolated these results into my standard BAC categories by assuming uniform density of observations within each of the study?s BAC categories. <0.01 202.00 80.31 14.00 41.12 0.51 1.00 0.01-0.049 19.48 7.75 1.10 3.23 0.42 0.82 0.05-0.099 21.09 8.39 1.86 5.46 0.65 1.27 0.10-0.149 2.96 1.18 0.66 1.94 1.64 3.21 ~0.15 5.99 2.38 16.43 48.25 20.27 39.73 The predominant flaw of this study is the small sample size, which allows us to put little confidence in the results. VERMONT M. W. Perrine, Wailer, J. A., and Harris, L. S. (1971) Alcohol and Highway Safety: Behavioral and Medical Aspects. National Highway Traffic Safety Administration technical report DOT-HS-800-599. Wash- ington, D.C.: U.S. Department of Transportation. Case group was fatally injured drivers in Vermont from July 1, 1967, to April 30, 1968. Control group was pooled data of: (1) six drivers at same place, time of day, and day of week as each observation in case group, either within a few weeks or one year after accident being matched; and (2) six drivers at same place, time of day, and day of week as each observation from
378 REED a group of crashes occurring in Vermont in 1966 and resulting in an injury warranting hospitalization, each observation of which was chosen as a close match to one observation in the case group. The report's account of control group selection is unclear and self- contradicting. The report justifies pooling the two samples by showing that there is a significant difference in the distribution within either sample of only 3 of 22 variables. I suspect that the control group shows fewer high BAC levels than were actually present among drivers at times and places similar to those of case group crashes. Of control group 1.3 percent refused the BAC test. BAC test was performed on all members of the case group. The lowest BAC category used in the report is <0.02. I have inter- polated into my standard BAC categories by assuming that the density of observations in the interval 0.01 SAC <0.02 is the same as the density in the interval 0.02 ~ BAC ~0.04. All other categories in the report are comparable to mine. TABLE A-8 Vermont: Survey Results and Relative Risk BAC # Control % Control # Accident Do Accident Ratio Risk <0.01 942.10 83.74 47.62 44.92 0.54 1.00 0.01~.049 104.90 9.32 5.38 5.08 0.55 1.02 0.05-0.099 54 4.80 9 8.49 1.77 3.27 0.1~0.149 13 1.16 14 13.21 11.39 21.07 ~0.15 11 0.98 30 28.30 28.88 53.43 The "risk" figures for the higher BAC categories are probably biased upward somewhat due to flaws in the control group. APPENDIX B: ADJUSTING VERMONT DATA TO REFLECT ALL FATAL ACCIDENTS The Vermont Study (see Appendix A) reports the BAC levels only for fatally injured drivers, but for purposes of computing the possible savings from drinking-driving countermeasures we need to know the BAC dis- tribution of all drivers involved in accidents in which anyone was killed. To adjust the Vermont data to reflect all fatal accidents, I use data presented by Sterling-Smith (1976, p. 135~. Sterling-Smith studies the drivers judged to have been "most responsible" for each of 267 fatal traffic accidents in the Boston area from 1971 to 1974. He presents a breakdown of this group of drivers by BAC range and whether the fatality was the driver or another person. Table B-1 shows these results.
Reducing the Costs of Drinking and Driving TABLE B-1 Number of Drivers Responsible for Fatal Accidents, Boston, 1971-1974 BAC (5to) Driver Killed Other Killed <0.01 29 1 16 0.01-0.04 6 13 ~0.05 68 35 TOTAL 103 164 Source: Sterling-Smith (1976, p. 135~. 379 Table B-1 cannot be directly applied to the Vermont data. Since Boston is much more urbanized than Vermont, there is a greater density of vehicles and pedestrians for a driver to collide with, and we would expect a lower ratio of driver fatalities to all fatalities than in Vermont. The data bear this out. According to Table B-1 driver fatalities comprise 39 percent of fatal accidents in the Boston area, whereas Perrine et al. (1971, p. 42) report that the ratio in Vermont in the early 1970s was 59 percent. To adjust the Boston data to those of Vermont, I reduced the number of nondriver fatalities ("other killed") until driver fatalities comprised 59 percent of total fatalities. I multiply the number of nondriver fatalities in each BAC range by 72/164 to arrive at the figures in Table B-2. TABLE B-2 Adjusted Number of Drivers Responsible for Fatal Accidents BAC (%) Driver Killed Other Killed Total Killed <0.01 29 5 1 80 0.01-0.04 6- 6 12 ~0.05 68 15 83 TOTAL 103 72 175 By dividing the "total killed" figure by the "driver killed" figure for each BAC range in Table B-2, I obtain for each range an estimate of the ratio of all fatal accidents to driver-fatal accidents in Vermont. Let us call the ratio for the ith BAC range Ri. The percentage of driver fatalities in each BAC range, as listed in Appendix A, is D'. Then it is clear that the percentage of all fatalities in the ith BAC range is Ti = ~;ij; lOO~o.
380 REED Table B-3 shows Ti for each BAC range. The control group figures need no adjustment, so they are merely reproduced in Table B-3 as they appeared in Appendix A (with the three highest BAC ranges summed). TABLE B-3 Percentage of Drivers Involved in Fatal Accidents, and of Control Group Drivers, Estimated to Be Within Three BAC Ranges BAC (DO) Accident (5to) Control (%) 84 <0.01 64 0.01-0.04 5 30.05 31 APPENDIX C: RELATIVE RISK AND ACCIDENT REDUCTION CONTROLLED EPIDEMIOLOGICAL STUDIES Among the most valuable studies of drinking-driving problems are con- trolled epidemiological studies, such as those reviewed in Appendix A of this paper. In these studies, a random (or exhaustive) sample of drivers involved in accidents in a set geographic area and time period is made. The BAC of each driver in the sample is measured at the time of the accident. These drivers constitute the "accident group." In addition, researchers match a "control site" to each observation in the accident group. The control site is ideally the same place, at the same time of day and day of the week, under similar weather conditions, and otherwise nearly identical to the circumstances under which the accident being matched occurred. Several drivers passing each control site are randomly selected and their BAC levels measured. These ob- servations constitute the "control group." Drivers in both the accident group and control group are classified into BAC ranges, and the results are presented in Table C-1. I use the results of a controlled epidemiological study, as presented in Table C-1, to estimate the results of an imaginary experiment that is impractical to actually perform. The imaginary experiment is to ran- domly sample "units of accident exposure" and record driver BAC and whether an accident occurs for each unit of exposure selected. A unit of accident exposure would be a period of driving during which a "stand- ard" driver would have some particular expected number of accidents.
Reducing the Costs of Drinking and Driving TABLE C-1 Results of a Controlled Epidemiological Study Number of Accident BAC Range Group Drivers Number of Control Group Drivers O a`, c<, 1 al Cl n a,, en 381 For example, driving for 1 hour (or 1 mile) at night in the rain on a narrow twisting road would constitute more units of exposure to accident than would 1 hour (or 1 mile) of driving on a sunny day on a well- designed expressway. If we could perform the imaginary experiment, then we could answer two important questions: (1) What are the probabilities of an accident occurring when one unit of accident exposure is driven by a driver at various BAC levels? (2) What would be the reduction in number of accidents if all driving was done by drivers in the lowest BAC range? ESTIMATING RELATIVE RISKS What is the probability that a random unit of exposure results in an accident, given that the driver is in some particular BAC range? To answer this question, I invoke Bayes's theorem: P`A~i~ - (A n i) = . p (i) ~ where (1) P(A~i) is the probability that a given unit of exposure results in an accident, given that the driver is in the ith BAC range. UP n id is the probability that a randomly chosen unit of driving results in an accident, and that the driver is in the ith BAC range. P(i) is the probability that a randomly selected unit of ex- posure is driven by a driver in the ith BAC range. 'The Bayesian analysis used in this and the following section has been applied to drunk driving before, notably by Hurst (1970, 1973~.
382 Also from Bayes's theorem: Substituting (2) into (1~: REED P(Ani) =P(i~A)P(A). P`A~i' P(i~A) P(A) . (2) (3) Referring back to Table C-1, we see that Pupil) = at/~.ai, since the accident group is a random sample of units of exposure resulting in accidents. We can use c,/Ici as a proxy for P(i), because the probability of a driving trip being included in the control group is primarily deter- mined by the likelihood that a similar trip resulted in an accident. Thus, the control group approximates a random sample of units of exposures We can thus rewrite (3) as: 2 The probability of any given trip being included in the control group can be expressed as: P(T ~ C) = N E D (SIN - R), where P(T ~ C) is the probability that trip T becomes an element of the control group. N is the number of trips (including trip T) to which trip T could be matched as a control (i.e., the number of trips passing sites for which the site of T might be a control site). is the mean exposure to accident of each of the N trips. D is the risk multiplier due to the fraction of drivers among the N trips who have elevated BAC levels. S is the number of trips sampled at each control site. R is the probability that trip T ends in an accident before the car reaches the site where it would have been sampled for the control group. I make the simplifying assumptions that L) approaches one and R approaches zero. We are left with: P(T ~ c) = ES. S is a constant, so the probability that trip T is included in the control group is ap- proximately equal to the expected value of the exposure to accident of trip T.
Reducing the Costs of Drinking and Driving We can thus rewrite (3) as: P`<A ~i' = (` . ~ ;) PEA 383 (4) Note that controlled epidemiological studies do not provide sufficient information to determine P(A~i), the probability that a randomly se- lected unit of exposure will result in an accident. We cannot determine the absolute value of P(A~i). We can? however, determine its value for all values of i relative to its value for i = 0 (i.e., for the lowest BAC range): P(A~i) ai cO = ~ P(A~O) c' an (5) I will refer to P(A~i~lP(A~O) as the relative risk of driving in BAC range i. Thus, the relative risk of the lowest BAC range is always one. Table C-2 shows the relative risk of driving in several BAC categories, as derived from the controlled epidemiological studies in Table 1 of this paper. TABLE C-2 Relative Risk of Accident Involvement per Unit of Driving in Various BAC Ranges' as Computed from Several Studies Injury Property Damager Fatal, Injury, Grand Rapids. Grand Rapids, Vermont, Huntsville. Ala Mich Mich., BAC (%) 1967-1968 197~1975 1962-1963 1962-1963 <0.01 1.0 1.0 1.0 1.0 0.01~.049 0.7 1.4 0.9 0.9 0.0~0.099 2.0 1.8 1.5 3~0.15 5.8 13 4 ~ 10.8 ~ 8.0 PREDICTING ACCIDENT REDUCTION The total number of accidents of a given severity that one would expect to occur in a given area during a given period may be expressed as: IBi= IP(A~i)E,, (6) where Bi is the expected number of accidents involving drivers in BAC range i; Ei is the units of exposure to accident driven by drivers in BAC range i.
384 REED Note that as long as P (A~O) remains constant, relative risk for BAC range i is a linear function of P(A~i). Also, ci approximates a linear function of Ej (see note 2~. Thus, we can rewrite (6) as: IBi = P(A o) Ci ~ (7) where Bi is a linear function of Bi A I will refer to Bi as the relative number of accidents involving drivers in BAC range i. If all drunken driving was eliminated, without changing any individual's driving patterns (mileage, route, etc.), then we would compute a new Bi for each BAC range merely by setting relative risk for every range equal to one. Thus, if a "perfect" drinking-driving coun- termeasure was to go into effect, the total expected relative number of accidents would be: A IB;= Ec;. (8) In Table C-3' I present Bj for each BAC range' and IBi' for each of the studies in Table C-2, computed both with and without a "perfect" drinking-driving countermeasure in effect. The percentage change in B when the perfect countermeasure is figured in predicts the percentage change in the absolute expected number of accidents if such a counter- measure was implemented. TABLE C-3 Relative Number of Accidents Involving Drivers in Various BAC Ranges, Without and With a Perfect Drunk-Driving Countermeasure, for Four Studies Injury. Injury, Grand Property Damage. Fatal, Vermont Huntsville' Ala Rapids. Mich Grand Rapids, 1967-1968 1974-1975 1962-1963 Mich., 1962-1963 BAC (%) (Without/With) (Without/With) (Without/With) (Without/With) <0.01 84 84 88.2 88.2 89.0 89.0 89.0 89.0 0.01-0.049 6 9 6.0 4.3 7.0 7.8 7.0 7.8 0.05-0.099 9.4 4.7 4.5 2.5 3.8 2.5 0.10-0.149 41 7 5 7 2 1 ~ 8 6 ~ 0.8 6.4 0.8 ~0.15 9.4 0.7 ) ~ SUM 131 100 118.7 100.0 109.1 100.1 106.2 10().1
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