Effects of enforcement intensity on alcohol impaired driving crashes

Background

Research measuring levels of enforcement has investigated whether increases in police activities (e.g., checkpoints, driving-while-intoxicated [DWI] special patrols) above some baseline level are associated with reduced crashes and fatalities. Little research, however, has attempted to quantitatively measure enforcement efforts and relate different enforcement levels to specific levels of the prevalence of alcohol-impaired driving.

Objective

The objective of this study was to investigate the effects of law-enforcement intensity in a sample of communities on the rate of crashes involving a drinking driver. We analyzed the influence of different enforcement strategies and measures: (1) specific deterrence – annual number of driving-under-the-influence (DUI) arrests per capita; (2) general deterrence – frequency of sobriety checkpoint operations; (3) highly visible traffic enforcement – annual number of traffic stops per capita; (4) enforcement presence – number of sworn officers per capita; and (5) overall traffic enforcement – the number of other traffic enforcement citations per capita (i.e., seat belt citations, speeding tickets, and other moving violations and warnings) in each community.

Methods

We took advantage of nationwide data on the local prevalence of impaired driving from the 2007 National Roadside Survey (NRS), measures of DUI enforcement activity provided by the police departments that participated in the 2007 NRS, and crashes from the General Estimates System (GES) in the same locations as the 2007 NRS. We analyzed the relationship between the intensity of enforcement and the prevalence of impaired driving crashes in 22–26 communities with complete data. Log-linear regressions were used throughout the study.

Results

A higher number of DUI arrests per 10,000 driving-aged population was associated with a lower ratio of drinking-driver crashes to non-drinking-driver crashes (p = 0.035) when controlling for the percentage of legally intoxicated drivers on the roads surveyed in the community from the 2007 NRS. Results indicate that a 10% increase in the DUI arrest rate is associated with a 1% reduction in the drinking driver crash rate. Similar results were obtained for an increase in the number of sworn officers per 10,000 driving-age population.

Discussion

While a higher DUI arrest rate was associated with a lower drinking-driver crash rate, sobriety checkpoints did not have a significant relationship to drinking-driver crashes. This appeared to be due to the fact that only 3% of the on-the-road drivers were exposed to frequent sobriety checkpoints (only 1 of 36 police agencies where we received enforcement data conducted checkpoints weekly). This low-use strategy is symptomatic of the general decline in checkpoint use in the U.S. since the 1980s and 1990s when the greatest declines in alcohol-impaired-driving fatal crashes occurred. The overall findings in this study may help law enforcement agencies around the country adjust their traffic enforcement intensity in order to reduce impaired driving in their community.     

Why are sobriety checkpoints not widely adopted as an enforcement strategy in the United States?

Sobriety checkpoints have been used by police in the United States for at least the past two decades to enforce impaired driving laws. Research has indicated that sobriety checkpoints are effective in reducing drinking and driving and alcohol-related fatal crashes. Despite this evidence, many police agencies have been unenthusiastic about using checkpoints. Information was collected from all 50 states plus the District of Columbia on the use of sobriety checkpoints. A total of 37 states and the District of Columbia reported conducting sobriety checkpoints at least once or twice during the year. Only 11 states reported that checkpoints were conducted on a weekly basis. Thirteen states do not conduct checkpoints either because of legal or policy issues. More detailed information was collected from five states that conduct checkpoints frequently and matched with information from five similar states that conduct checkpoints infrequently. States with frequent checkpoint programs had several common features such as program themes, support from task forces and citizen activist groups, use of a moderate number of police at the checkpoints, and use of all available funding mechanisms (federal, state, local) to support them. States with infrequent checkpoints claimed a lack of funding and police resources for not conducting more checkpoints, preferred saturation patrols over checkpoints because they were more “productive,” and used large numbers of police officers at checkpoints. Ways to overcome perceived barriers to checkpoint use are discussed.     

Deterring the drinking driver: the Stockton experience

The effectiveness of drunk driving enforcement patrols is generally assumed. However, few adequate evaluations are available in the traffic safety literature. The U.S. Department of Transportation funded a special program in Stockton, a city with a population of 120,000 in the central valley of California, to test the effectiveness of special drunk driving patrols on weekend evenings, applied within a setting in which no other major alcohol safety programs were present. The objective of this effort was to determine the effectiveness of a "traditional" approach to enforcing driving while impaired (DWI) laws; one in which innovative procedures such as sobriety checkpoints were not used. The results indicated that nighttime collisions in Stockton were reduced during the three and a half year period of the special enforcement program.     

Prevalence of alcohol-impaired drivers based on random breath tests in a roadside survey in Catalonia (Spain)

Sobriety checkpoints are not usually randomly located by traffic authorities. As such, information provided by non-random alcohol tests cannot be used to infer the characteristics of the general driving population. In this paper a case study is presented in which the prevalence of alcohol-impaired driving is estimated for the general population of drivers. A stratified probabilistic sample was designed to represent vehicles circulating in non-urban areas of Catalonia (Spain), a region characterized by its complex transportation network and dense traffic around the metropolis of Barcelona. Random breath alcohol concentration tests were performed during spring 2012 on 7596 drivers. The estimated prevalence of alcohol-impaired drivers was 1.29%, which is roughly a third of the rate obtained in non-random tests. Higher rates were found on weekends (1.90% on Saturdays and 4.29% on Sundays) and especially at night. The rate is higher for men (1.45%) than for women (0.64%) and it shows an increasing pattern with age. In vehicles with two occupants, the proportion of alcohol-impaired drivers is estimated at 2.62%, but when the driver was alone the rate drops to 0.84%, which might reflect the socialization of drinking habits. The results are compared with outcomes in previous surveys, showing a decreasing trend in the prevalence of alcohol-impaired drivers over time.     

Are lower legal blood alcohol limits and a combination of sanctions desirable in reducing drunken driver-involved traffic fatalities and traffic accidents?

In 1970 and 1978, a set of strict new countermeasures against drunk driving went in to effect in Japan. Analysis of official statistics of motor vehicle fatality data have indicated that alcohol involvement in fatal crashes has declined substantially in Japan since 1970. From the beginning of 1970 to the late 1980s and 1990s, public awareness of and tolerance for the problem of alcohol-impaired driving changed dramatically, as shown in this study. Further it seems that attitudes in Japan on drink driving have improved over the last 20 years or so, instep with a major program of government action. As well as being part of a long running campaign to reduce alcohol related road deaths and injuries, these accident savings are an important part of a national strategy which began in 1970, comprising a well structured legislative program introducing a lower legal limit, progressive penalties for those above the legal limit, over and above Police enforcement strategies underpinning the law and reinforcing the publicity massage. Enactment of the lower legal blood alcohol level with a combination of other severe sanctions is desirable for prevention of alcohol-related traffic casualties, DWI, and accidents, which is shown in this study. Finally, much of the current reduction in alcohol-related fatalities and morbidity reflects that Japanese society has largely endorsed alcohol impaired driving as a socially undesirable behavior. However, this study suggests that it is necessary for policy makers to understand that the DUI problem in Japan must be handled with diverse approaches, rather than relying exclusively on the deterrence based laws.     

Alcohol-impaired driving behavior and sensation-seeking disposition in a college population receiving routine care at campus health services centers

Accidents stemming from alcohol-impaired driving are the leading cause of injury and death among college students. Research has implicated certain driver personality characteristics in the majority of these motor vehicle crashes. Sensation seeking in particular has been linked to risky driving, alcohol consumption, and driving while intoxicated. This study investigated the effect of sensation seeking on self-reported alcohol-impaired driving behavior in a college student population while adjusting for demographics, residence and drinking locations. A total of 1587 college students over the age of 18 completed a health screening survey while presenting for routine, non-urgent care at campus heath services centers. Student demographics, living situation, most common drinking location, heavy episodic drinking, sensation-seeking disposition and alcohol-impaired driving behavior were assessed. Using a full-form logistic regression model to isolate sensation seeking after adjusting for covariates, sensation seeking remains a statistically significant independent predictor of alcohol-impaired driving behavior (OR = 1.52; CI = 1.19-1.94; p < 0.001). Older, white, sensation-seeking college students who engage in heavy episodic drinking, live off-campus, and go to bars are at highest risk for alcohol-impaired driving behaviors. Interventions should target sensation seekers and environmental factors that mediate the link between sensation seeking and alcohol-impaired driving behaviors.     

Retail alcohol monopolies, underage drinking, and youth impaired driving deaths

OBJECTIVE: To explore associations of state retail alcohol monopolies with underage drinking and alcohol-impaired driving deaths. DATA: Surveys on youth who drank alcohol and binge-drank recently and their beverage choices; census of motor vehicle fatalities by driver blood alcohol level. METHODS: Regressions estimated associations of monopolies with under-21 drinking, binge drinking, alcohol-impaired driving deaths, and odds a driver under 21 who died was alcohol-positive. RESULTS: About 93.8% of those ages 12-20 who consumed alcohol in the past month drank some wine or spirits. In states with a retail monopoly over spirits or wine and spirits, an average of 14.5% fewer high school students reported drinking alcohol in the past 30 days and 16.7% fewer reported binge drinking in the past 30 days than high school students in non-monopoly states. Monopolies over both wine and spirits were associated with larger consumption reductions than monopolies over spirits only. Lower consumption rates in monopoly states, in turn, were associated with a 9.3% lower alcohol-impaired driving death rate under age 21 in monopoly states versus non-monopoly states. Alcohol monopolies may prevent 45 impaired driving deaths annually. CONCLUSIONS: Continuing existing retail alcohol monopolies should help control underage drinking and associated harms.     

Traffic officers'' attitudes toward blood alcohol law enforcement

Research findings in other countries suggest that drinking driving laws could be much better enforced even without resorting to special patrols or random checks. It has been reported that law enforcement officers apprehend or breath test only a small fraction of the potentially impaired drivers that they normally encounter on patrol. This survey of New Zealand traffic officers was designed to determine the extent to which this was the case here, and what were the major disincentives to breath testing. Traffic officer responses, obtained on an anonymous questionnaire, suggested that there were not so many missed opportunities as had been suggested by others, but that there was a great deal of variability in the number of drinking drivers detected by different officers. This was confirmed by the actual distribution of breath testing activity, which was markedly different in shape (positively skewed) compared to the distribution of traffic enforcement activities in general. Several clues from the disincentives cited on the questionaire suggested that there are major deterrents to a greater degree of alcohol enforcement activity on the part of most officers. These are discussed in terms of potential legislative changes, and in relation to the changes introduced in the 1978 Transport Act Amendment.     

Hurried driving: Relationship to distress tolerance,driver anger,aggressive and risky driving in college students

Being a hurried driver is associated with a variety of risky driving behaviors, yet the mechanisms underlying this behavior remain unknown. Distress tolerance, defined as an individual's capability to experience and endure negative emotional states, was examined as a predictor of hurried driving among 769 college students. Results indicate that after controlling for age, gender, race, ethnicity, the student's year in school, their grade point average, driving frequency, angry driving, aggressive driving as well as other forms of self-reported risky driving; hurried driving was significantly associated with lower levels of distress tolerance. Hurried drivers also reported greater levels of frustration and impatience with other drivers, suggesting that they have difficulty in withstanding or coping with negative psychological states when driving. Traditional traffic safety campaigns that emphasize enforcement may be less successful with these drivers. The need to develop campaigns that address the affective coping abilities that contribute to this behavioral pattern is discussed.     

Recent evidence from scandinavia on deterring alcohol impaired driving

This paper summarizes the results of a number of studies of the effectiveness of control of drunken driving in Norway and Sweden. Econometric techniques are used for these evaluations within a simultaneous systems framework that takes account of variations in law enforcement effort, levels of alcohol consumption, and environmental effects that include indices of distance driven, vehicle mix and/or traffic density, and road quality. Effectiveness is measured in terms of the impact on fatal and serious injury accidents. Both cross-section and time series analyses have been conducted for periods in which legal statutes have remained relatively unchanged. Across all of the data sets involved there is a substantial unanimity supporting the hypothesis that increases in alcohol consumption levels are associated with higher accident levels and increases in law enforcement effort leading to a greater probability of sanctions will result in lower levels of fatal and serious injury accidents than would otherwise prevail.     

Decisions relating to alcohol-impaired driving: An exploratory analysis

This paper focuses on an individual's decision to drive or not to drive after drinking. To evaluate this decision, a utility maximizing probabilistic choice model is specified and estimated using a sample of college students. The estimation results provide interesting insights relating to the potential effectiveness of drinking-driving countermeasures, and suggest that the most effective methods of reducing the probability of driving after drinking are those advertising and awareness campaigns that focus on altering individual preferences.     

Using a multidimensional Rasch model approach to measure the police's perceived ability to detect,detain and intercept DWI vehicles when conducting sobriety checkpoints

This study developed a scale to measure 502 Taiwan traffic police officers’ perceived ability to detect, detain, and intercept those vehicles whose drivers are driving while intoxicated (DWI) when conducting sobriety checkpoints. Through factor analysis, the officers’ enforcement ability was found to consist of two component latent traits: detecting ability (DA) and detaining and intercepting ability (DIA). A multidimensional approach of Rasch models was then applied to measure the police officers’ perceived abilities and particular difficulties in conducting sobriety checkpoints. The study results indicated that the majority of police officers performed well in detecting DWI vehicles, but half of the study participants lacked confidence in detaining DWI vehicles and intercepting escaping DWI vehicles. DWI with weaving was found to be the most aggressive and threatening behavior to traffic police when conducting sobriety checkpoints. Police officers over age 46 were found to have significantly lower DA and DIA, while branch captains were found to have significantly higher DA than their colleagues. Several strategies and programs are suggested based on the study findings to improve the enforcement ability of police officers.     

The role of sensation seeking,perceived peer pressure,and harmful alcohol use in riding with an alcohol-impaired driver

Alcohol-related motor vehicle collisions have been the top of policy agenda for more than three decades in Korea. Despite implementation of various traffic safety measures, some drivers’ alcohol use and abuse has resulted in a high number of alcohol-impaired traffic fatalities every year. This paper presents the association of theoretical factors with behavior of riding with an alcohol-impaired driver (RAID) among all age groups in the Korean adult sample. The theoretical factors of the drivers are personality factor, socio-psychological factor, and alcohol-related behavioral risk factor. We utilized national survey data from 1007 respondents consisting of 703 males and 304 females aged 20–66 collected by Korean Institute of Criminology (KIC) to test our theorized model. Our results indicated that there were three major predictors of RAID involvement: sensation seeking propensity, perceived peer pressure, and frequent harmful drinking. Overall, prediction of RAID behavior by gender was mediated entirely through these predictors. The issue of males’ higher risk of RAID involvements was addressed for effective communication strategies such as campaigns.     

The influence of safety belt laws on self- reported safety belt use in the United States

We assessed rates and trends in safety belt use by presence and type of safety belt law using data from states participating in the 1984–1989 Behavioral Risk Factor Surveillance System. State(s) with a safety belt law allowing law enforcement officers to stop vehicles for occupants' failure to use safety belts (primary enforcement law) had greater and more rapid increases in safety belt use rates than did states with laws requiring that vehicles must first be stopped for some other violation before a citation or fine for occupants' failure to use safety belts could be imposed (secondary enforcement law). Larger and sustained increases in safety belt use occurred when safety belt laws became effective or when fines were imposed for violations than when laws were first enacted. These data suggest that primary enforcement laws result in greater and more rapid increases in safety belt use than do secondary enforcement laws, and that initial increases in safety belt use following implementation of laws are sustained.     

Reducing alcohol-impaired driving crashes through the use of social marketing

Over the past decade there has been little decrease in the number of alcohol-related driving fatalities. During this time most interventions have been educational or legal. This paper presents the results of a field experiment that used social marketing to introduce a new ride program into three rural communities. Almost all people in the 21–34-year-old target know that they should not drive while impaired, and most agree it is not a good thing to do, but for many the opportunity to behave properly does not exist. The Road Crew program was developed using new product development techniques and implemented by developing broad coalitions within the communities. A key feature of the program included rides to, between, and home from bars in older luxury vehicles. Results showed a significant shift in riding/driving behavior, especially among 21–34-year olds, a projected 17% decline in alcohol-related crashes in the first year, no increase in drinking behavior, and large savings between the reactive cost of cleaning up after a crash and the proactive cost of avoiding a crash. Programs have become self-sustaining based on fares and tavern contributions, and have become part of the life style in the treatment communities.     

Trends in alcohol-impaired driving in Canada

While a general decreasing trend in the number of persons killed in a traffic crash involving a drinking driver has occurred in Canada since the 1980s, it is evident that much of this decrease occurred in the 1990s. Since 2002, less progress has been made as the number of persons killed in crashes involving drinking drivers remains high. To better understand the current situation, this paper describes trends in drinking and driving in Canada from 1998 to 2011 using multiple indicators based on data collected for the Traffic Injury Research Foundation's (TIRF) Road Safety Monitor (RSM), the National Opinion Poll on Drinking and Driving, and trends in alcohol-related crashes based on data collected for TIRF's national Fatality Database in Canada. There has been a continued and consistent decrease in the number of fatalities involving a drinking driver in Canada. This remains true when looking at the number of fatalities involving a drinking driver per 100,000 population and per 100,000 licensed drivers. This decreasing trend is also still apparent when considering the percentage of persons killed in a traffic crash in Canada involving a drinking driver although less pronounced. Data from the RSM further show that the percentage of those who reported driving after they thought they were over the legal limit has also declined. However, regardless of the apparent decreasing trend in drinking driving fatalities and behaviour, reductions have been relatively modest, and fatalities in crashes involving drivers who have consumed alcohol remain high at unacceptable levels.     

Seat belt use among 13-15 year olds in primary and secondary enforcement law states

CONTEXT: Coverage and enforcement provisions of safety belt use laws vary by state. Most laws cover drivers and passengers age 16 and above. "Primary" enforcement laws allow police to stop and ticket a motorist for a safety belt law violation. With "secondary" enforcement laws, ticketing can only occur in the presence of another traffic infraction. Given the lower rates of restraint use among teen drivers and their passengers, the effect of primary enforcement laws on the restraint use of young teen passengers is of particular interest. OBJECTIVE: To compare restraint use by 13-15 year olds passengers in motor vehicle crashes in states with primary versus secondary enforcement safety belt laws. METHODS: Cross-sectional study of 3953 crashes involving 5372 children, representing 54,226 children aged 13-15 years in 41,198 crashes of insured vehicles in 16 states and Washington, DC between December 1, 1998 and December 31, 2004, with data collected via insurance claims records and a telephone survey. RESULTS: Non-use of restraints by 13-15 year olds was 7.2% (95% CI 4.3-10.1%) greater in secondary enforcement states (10.8%) as compared to states with primary enforcement laws (3.6%). After controlling for driver's age and restraint status and the seating row of the occupant, a 13-15 year olds was over twice as likely to be unrestrained in a secondary enforcement state as compared to a primary enforcement state (adjusted RR=2.2, 95% CI 1.5-3.1). CONCLUSIONS: States considering primary enforcement provisions to their restraint laws should consider the potential benefits these laws may have to all occupants in the vehicle, particularly young adolescents who are nearing driving age.     

“I drove after drinking alcohol” and other risky driving behaviours reported by young novice drivers

Background: Volitional risky driving behaviours such as drink- and drug-driving (i.e. substance-impaired driving) and speeding contribute to the overrepresentation of young novice drivers in road crash fatalities, and crash risk is greatest during the first year of independent driving in particular. Aims: To explore the: (1) self-reported compliance of drivers with road rules regarding substance-impaired driving and other risky driving behaviours (e.g., speeding, driving while tired), one year after progression from a Learner to a Provisional (intermediate) licence; and (2) interrelationships between substance-impaired driving and other risky driving behaviours (e.g., crashes, offences, and Police avoidance). Methods: Drivers (n = 1076; 319 males) aged 18–20 years were surveyed regarding their sociodemographics (age, gender) and self-reported driving behaviours including crashes, offences, Police avoidance, and driving intentions. Results: A relatively small proportion of participants reported driving after taking drugs (6.3% of males, 1.3% of females) and drinking alcohol (18.5% of males, 11.8% of females). In comparison, a considerable proportion of participants reported at least occasionally exceeding speed limits (86.7% of novices), and risky behaviours like driving when tired (83.6% of novices). Substance-impaired driving was associated with avoiding Police, speeding, risky driving intentions, and self-reported crashes and offences. Forty-three percent of respondents who drove after taking drugs also reported alcohol-impaired driving. Discussion and Conclusions: Behaviours of concern include drink driving, speeding, novice driving errors such as misjudging the speed of oncoming vehicles, violations of graduated driver licensing passenger restrictions, driving tired, driving faster if in a bad mood, and active punishment avoidance. Given the interrelationships between the risky driving behaviours, a deeper understanding of influential factors is required to inform targeted and general countermeasure implementation and evaluation during this critical driving period. Notwithstanding this, a combination of enforcement, education, and engineering efforts appear necessary to improve the road safety of the young novice driver, and for the drink-driving young novice driver in particular.     

Legal consequences for alcohol-impaired drivers injured in motor vehicle collisions: A systematic review

Background

The treatment of alcohol-impaired drivers injured in a motor vehicle collision (MVC) is a complex public health issue. We conducted a systematic review to describe the legal consequences for alcohol-impaired drivers injured in a MVC and taken to a hospital or trauma center. Methods We searched MEDLINE, Embase, and CINAHL databases from inception until August 2014. We included studies that reported legal consequences including charges or convictions of injured drivers taken to a hospital or trauma center after a MVC with a blood alcohol concentration (BAC) exceeding the legal limit.Results Twenty-six studies met inclusion criteria; twenty studies were conducted in the USA, five in Canada, and one in Sweden. All were cohort studies (23 retrospective, 3 prospective) and included 11,409 patients overall. A total of 5,127 drivers had a BAC exceeding the legal limit, with legal consequences reported in 4937 cases. The median overall DUI/DWI conviction rate was 13% (range 0–85%). The median percentage of drivers with a previous conviction on their record for driving under the influence (DUI) or driving while intoxicated (DWI) was 15.5% (range 6–40%). The median percentage of drivers convicted again for DUI/DWI during the study period was 3.5% (range 2–10%). Heterogeneity between study designs, legal jurisdictions, institutional procedures and policies for obtaining a legally admissible BAC measurement precluded a meta-analysis. Conclusions The majority of intoxicated drivers injured in MVCs and seen in the emergency department are never charged or convicted. A substantial proportion of injured intoxicated drivers had more than one conviction for DUI/DWI on their police record.     

Stated response to increased enforcement density and penalty size for speeding and driving unbelted

To what extent can traffic offences be reduced through stronger enforcement, higher penalties, and the provision of information to road users? This question was addressed with respect to the offences of “speeding” and “driving unbelted.” Data were collected by a telephone survey of admitted speeders, followed by 438 face-to-face stated response interviews. Based on the data collected, separate statistical models were developed for the two offences. The models predict the behavioral effect of increasing enforcement density and/or penalty size as well as the additional effect of providing information to car drivers. All three factors are predicted to be effective in reducing speeding. According to the model, one additional enforcement event per year will cause a driver to reduce his current frequency of speeding by 5%. A penalty increase of 10 Euros is predicted to have the same effect. An announcement of stronger enforcement or higher fines is predicted to have an additional effect on behavior, independent of the actual magnitudes of increase in enforcement or fines. With respect to the use of a seat belt, however, neither an increase in enforcement density nor its announcement is predicted to have a significant effect on driver behavior. An increase in the penalty size is predicted to raise the stated wearing rate, which is already 90% in Austria. It seems that both the fear of punishment and the motivation for driving unbelted are limited, so that there is only a weak tradeoff between the two. This may apply to most traffic offences, with the exception of speeding, which accounts for over 80% of tickets alone, whereas all other offences account for less than 3% each.