Sjoerd Houwing* and René Mathijssen. SWOV Institute for Road Safety Research, Leidschendam, the Netherlands

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1 T2007 Seattle, Washington Drink-Driving Trend in the Netherlands Slowing Down Sjoerd Houwing* and René Mathijssen. SWOV Institute for Road Safety Research, Leidschendam, the Netherlands Background Between 1970 and 2006 drink driving declined by 80%. The most influencing factors that reduced the proportion of offenders were: technical improvements which made random and evidential breath testing possible in the eighties, legal amendments (introduction of a legal BAC limit in 1974 and the introduction of a lower limit for novice drivers in the beginning of 2006), increased enforcement levels, annual national publicity campaigns, more severe penalties, and driver improvement courses and medical assessment of fitness-to-drive for severe DUIoffenders. The proportion of high-bac drivers did not follow the downward trend in the last decennium. High-BAC drivers are responsible for almost three quarters of all serious alcohol related accidents in the Netherlands. Objectives and methodology This paper presents the drink-driving trend in the Netherlands as well as the trend of the alcohol-related road toll. Since 1970, annual roadside surveys have been conducted. The objective of these surveys is to obtain an insight into the patterns of drink-driving and into the effect of countermeasures. Roadside survey sessions are conducted during Friday and Saturday nights between 10 pm and 4 am, collecting data on about 30,000 motorists, annually. Breath testing is performed by police officers. Since random breath testing by the police is allowed in the Netherlands, non-response is virtually non-existent. Between 2000 and 2004, a large case-control study was conducted in the Netherlands to assess relative injury risk of driving under the influence of psychoactive substances. The case sample consisted of seriously injured car drivers who were admitted to the Emergency Department of the St. Elisabeth Hospital in the city of Tilburg. Controls consisted of motorists who were taken at random from moving traffic in the Tilburg police district which coffers the hospital's catchment area. Body fluids (blood and urine) of both cases and controls were analyzed for alcohol, and a number of licit and illicit drugs. The relative risk of these psychoactive substances was determined by calculating odds ratios. Furthermore, data on publicity campaigns, rehabilitation programmes, medical examinations, and crash data was collected and analyzed. Results Road side surveys On November 1st, 1974, a statutory BAC-limit of 0.5 g/l was introduced in the Netherlands. The police were given chemical test tubes for screening purposes and those who tested positive underwent a blood test for evidential purposes. The short-term effect of the introduction of the BAC-limit was enormous with an immediate decline of the proportion of offenders from 15% to 1%. But one year after the introduction the proportion went upward again to 11% (SWOV,

2 1978).The strong decrease in 1974 was more likely due to an increased risk of apprehension and punishment than to the introduction of the legal limit itself. Development drink driving offenders (in %) Offenders (in %) Development drink driving offenders (in %) Years Figure 1. Development drink driving offenders Between the late seventies and the early eighties, police enforcement remained more or less at the same level and despite mass media campaigns the proportion of offenders slightly increased and subsequently stabilised until the mid-eighties at 12%, which is nevertheless still significantly lower than in In 1984 electronic breath alcohol screening devices were introduced which were cheaper, more reliable and easier-to-handle than the chemical test tubes. Police were now able to test larger number of drivers than before and to introduce random breath testing, thus strongly increasing the risk of apprehension. In 1987 evidential breath testing was introduced, which was less time consuming and cheaper than evidential blood testing. From this moment on the police was able to test more drivers, and penalties for drink driving were administered quicker (Mathijssen, 2004). Between 1983 and 1987 the proportion of offenders dropped again from 12% to 8% and even to 3.9% in In the early 90s Dutch policeforces were reorganized which led to a rise in the proportion of drink driving offenders from 3.9% in 1991 to 4.9% in 1994 despite more severe sanctions for driving with an illegal BAC. After the reorganization had finished the proportion of drivers with an illegal BAC stabilized just around 4.5% at the beginning of the new millenium. The formation of special traffic enforcement units in 7 out of the 25 Dutch police regions in 1999, did not result in a higher enforcement level throughout the country (Mathijssen, 2002). In 1996 administrative sanctions were imposed, after the intorduction of more severe punishment under criminal law in 1992 did not result in a decrease of drink driving. Both a

3 medical/psychiatric assessment of fitness-to-drive and a driver improvement program were introduced: the so-called Educational Measure Alcohol and traffic (EMA) program. This program aims at influencing the drivers' attitude towards drink driving. An evaluation study in 1999 concluded that EMA did not have a significant effect on repeat drink driving (Vissers, 2002). As a result of the evaluation study, the course was improved. After a period with a more or less stable proportion of illegal BACs, the drink-driving trend further decreased from 2003 to present. In 2003 special regional traffic enforcement units were established in all Dutch police regions, resulting in a higher enforcement level. At the same time new mass media campaigns were held and the proportion of offenders dropped from 4.1% in 2002 to 3.0% in 2006 (AVV, 2007). However, the decline was solely visible among lower BAC levels ( 1.3 g/l). Despite efforts of police and government, the proportion of high BAC offenders (> 1.3g/l) did not decrease significantly over the past six years. Although the overall proportion drink-driving offenders dropped since 2000, the proportion of high-bac drivers remained the same, however. In absolute terms the number of alcohol related traffic fatalities decreased between 2003 and 2006, since the total number of traffic fatalities in the Netherlands dropped by a quarter during the same period. Since January 1 st 2006, the legal BAC limit for novice drivers was lowered from 0.5 g/l to 0.2 g/l. The introduction of a lower legal limit for novice drivers in Austria had a positive effect on traffic safety (Bartl et al., 2000). According to estimations by SWOV (Mathijssen, 1999) this countermeasure would save approximately 10 fatalities and 100 serious injuries per year. Table 1. Development of the proportion of alcohol related fatalities of young drivers (18-24 years) Proportion alcohol related serious accidents involving young car drivers (18-24) 14.2% 12.6% 16.1% 14.3% 18.0% Table 1 shows the development of alcohol related fatalities of young drivers aged 18 to 24. Despite the introduction the lower limit no effect was found in the 2006 accident figures either, allthough the results could have partially been the result of an increase of the proportion of young drivers caused by economical growth. Selective enforcement based on high risk hours and places, and large-scale publicity campaigns are needed to stimulate the compliance of the new law. Case-control study Tilburg During the case-control study that was conducted in the city of Tilburg blood and urine specimens from both seriously injured drivers and drivers from the general driving population were tested to determine the relative risk factors associated with the use of licit and illicit drug groups including alcohol. The eight drug groups included in the study were: alcohol, amphetamines, benzodiazepines, cannabis, cocaine, methadone, opiates and tricyclic depressants. The opiates group was subdivided into heroin, morphine and codeine. The amphetamines group was subdivided into amphetamines, methamphetamines and ecstasy. Among the general driving population, cannabis, benzodiazepines and alcohol were the prevailing substances. Out of the 3,799 stopped and tested drivers 2.1% were positive for

4 alcohol; 1.8% of them positive for alcohol alone and 0.3% for a combination of alcohol and drugs. Approximately 35% of the seriously injured car drivers were associated with the use of alcohol and/or drugs. BAC's above 1.3 g/l alone (12.7% of all seriously injured car drivers), BAC's above 0.8 g/l in combination with drugs (8.3%), and drug-drug combinations (7.2%) were prevailing. The corresponding odds ratios were 108, 104 and 10.2, respectively. Table 2. Use of psychoactive substances in traffic by young males Proportion among young males Proportion among all other groups Positive for drugs only 16.0% 4.0% Of which for drug-drug combination 1.4% 0.4% BAC g/l 2.6% 1.5% Of which in combination with drugs 1.0% 0.2% BAC 0.8 g/l 0.6% 0.5% Of which in combination with drugs 0.6% 0.03% Young male drivers have high risks. While.forming only 4% of the population, they are involved in 13% of the serious injuries. In the case of drink driving their involvement is even higher. Males from years form nearly a quarter of all alcohol-intoxicated drivers who are involved in serious injury accidents. Table 2 shows the results of the Tilburg case-control study in which young male drivers were especially overrepresented in the user groups of drug-alcohol and drug-drug combinations (Mathijssen and Houwing, 2005). Trend of alcohol related road injuries In the Netherlands the number of alcohol related fatalities is not known exactly since deceased road users are not tested alcohol. Although the proportion of offenders seems to be decreasing once again since 2003, the proportion of reported alcohol-related fatalities stayed more or less stable around 4%. Figure 2 shows the development of the reported and estimated road toll. The estimated alcohol-related road toll is much higher than the reported one. Estimates by the Ministry of Transport show a downward trend from almost 18% in 1999 to approximately 13 % in SWOV estimates are approximately twice as high and show a more or less stable level.

5 Estimated and Reported Proportion Alcohol Related Fatalities ,0 30,0 Proportion 25,0 20,0 15,0 10,0 Reported proportion alcohol related fatalities Estimation Ministry of Transport Estimation SWOV 5,0 0, Year Figure 2. Estimated and reported proportion of alcohol related fatalities The major difference between the two estimating methods is that the SWOV method is based on relative injury risks for the BAC-classes resulting from the Tilburg case-control study, while the Ministries method is based on relative accident risks from the Grand Rapids Study by Borkenstein et al. (1974). Especially at a high-bac the relative injury risk is much higher than the relative accident risk. Another important difference between the two methods is that SWOV includes the combined use of alcohol and drugs, whereas the Ministry of Transport excludes it (AVV, 2007). It is not clear however, how the Ministry is making a distinction between the two groups, since neither the subjects of the roadside survey, nor the deceased drivers are tested for drugs. Discussion During the last 35 years the Dutch government was very successful in reducing drink driving. Increased enforcement levels, legal amendments and technological developments resulted, together with national publicity campaigns and educational programs, in a downward trend of drink driving. The proportion of alcohol related fatalities decreased as well, although not to the same extend as the proportion of drink drivers. During the few last years the alcohol-related road toll seemed to remain more or less unchanged. The following high risk groups can be identified: high-bac drivers and young males, who are overrepresented among the cases of alcohol-drug and drug-drug combinations. With regard to young male drivers, the introduction of a lower legal BAC limit for novice drivers as of January ist 2006 is an important. High BAC-drivers may be targeted by more selective enforcement during high-risk hours and at high-risk places.

6 The Dutch government is aware of the increasing problem of drug use in traffic and the minister of Transport announced stricter legislation and enforcement. Regarding the high-bac drivers, extra selective enforcement on high risk hours and places might be a successful measure. Increased random breathtesting and more severe penalties do not seem to have a significant effect. More can be expected form the implementation of an alcohol interlock program. The implementation of an alcolock program in the Netherlands is foreseen for This alcolock program will target high-bac drivers and repeat offenders. The effect in terms of road safety will be dependent on the shape of the program, but expectations are high, based on the results of international evaluation studies (Beirness, 2001 Bax, 2001). References Bartl, G. and Neuberger, R. Effects of lowering the legal BAC-limit in Austria. Proc. 15 th International Conference on Alcohol, Drugs and Traffic Safety, Stockholm, Bax C (Ed.). Alcohol Interlock Implementation in the European Union; Feasibility Study. SWOV, Leidschendam, Beirness DJ, Best practices for Alcohol Interlock programs. Traffic Injury Research Foundation, Ottawa, Borkenstein RF, Crowther RF, Shumate WB, Ziel, WB, Zylman R. The role of the Drinking Driver in Traffic Accidents (the Grand Rapids Study). 2 nd ed. Blutalkohol 11, 1974; Supp.1. Dutch Ministry of Transport. Rijden onder invloed in Nederland in ; Ontwikkeling van het alcoholgebruik van automobilisten in weekendnachten. AVV, Rotterdam, Mathijssen, MPM. Schatting van de effecten van verlaging van de wettelijke limiet voor alcoholgebruik in het verkeer. R SWOV. Leidschendam, Mathijssen, MPM and Houwing, S. The prevalence and relative risk of drink and drug driving in the Netherlands: a case-control study in the Tilburg police district. R SWOV, Leidschendam, Mathijssen, MPM. Three decades of Drink Driving Policy in The Netherlands; An Evaluation. Proc. 17 th International Conference on Alcohol, Drugs and Traffic Safety, Glasgow, Mathijssen, MPM. Indecisive drink driving policy allows for increase of DUI in the Netherlands. Proc. 16 th International Conference on Alcohol, Drugs and Traffic Safety, Montreal, SWOV. Alcoholgebruik onder automobilisten; Verslag en resultaten van het onderzoek Rij- en drinkgewoonten van Nederlandse automobilisten in weekeindnachten in het najaar van de jaren, 1970, 1971, 1973, 1974, 1975 en R SWOV, Voorburg, 1978.

7 Vissers, JAMM and Van Beekum, RJ. The Educational Measure Alcohol and Traffic (EMA). Proc. 16 th International Conference on Alcohol, Drugs and Traffic Safety, Montreal, 2002.