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Alcohol Related Motor Vehicle Crashes ARMVC

Alcohol and Driving. Ethanol the active ingredient in alcohol reduces a driver's or pedestrian's perception, judgment, and motor skills.Experiments demonstrate that impairment begins when Blood Alcohol Concentration (BAC) > 0.0 ?one drink increases risk.State BAC limit is legal compromise, i.e.,

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Alcohol Related Motor Vehicle Crashes ARMVC

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    1. Alcohol Related Motor Vehicle Crashes (ARMVC) Development of Indicators for State and Local Prevention “No perfect Alternative” Harold D. Holder, Ph.D. Prevention Research Center Pacific Institute for Research and Evaluation Berkeley, CA

    2. Alcohol and Driving Ethanol the active ingredient in alcohol reduces a driver’s or pedestrian’s perception, judgment, and motor skills. Experiments demonstrate that impairment begins when Blood Alcohol Concentration (BAC) > 0.0 …one drink increases risk. State BAC limit is legal compromise, i.e., is prima facie evidence of impairment. As driver BAC increases, risk of crash increases

    3. Overview of Presentation Purpose of Data on Alcohol Related Motor Vehicle Crashes Self Reported Drinking and Driving DUI arrests Fatal Accident Reporting System State crash records-- Police Reports of “Alcohol Involved” crashes, surrogates What data is most useful for what purpose?

    4. Purposes of ARMVC Data State Epidemiological estimate of alcohol-involvement in traffic crashes. Indication of unique or important regional needs for prevention—comparison across areas of a state in terms of rates or levels of ARMVC can help planning and resource allocation. Local prevention evaluation

    5. Self Reported Drinking and Driving in the U.S.

    6. Challenges with “Self-Reported Drinking and Driving” Survey in which people self-report if they have driven after drinking. Substantial under reporting of actual number of events No real information on BAC level of driver. Survey sample not large enough to validly measure crashes. Can be used as intermediate variable of drinking and driving patterns/trends.

    7. Characteristics of Drinking Drivers in Fatal Crashes, U.S.

    8. Perfect Measurement of ARMVC The ideal for measuring ARMVC is to have every driver and pedestrian involved in any traffic crash tested for BAC, e.g., breath for living drivers and blood for dead drivers). Obviously the ideal is not likely to be implemented any time soon. ………probably not in our lifetime.

    9. Alternatives for Measuring Alcohol Related Motor Vehicle Crashes DUI arrests —local and state data Fatal Accident Reporting System (FARS)—National Highway Traffic Safety Administration, U.S. Dept. of Transportation —State reports of crashes in which at least one person died. State Traffic Crash Data –Every crash including police reported “had been drinking” or can develop surrogates developed from state data.

    10. DUI Arrests Unacceptable as measure of crashes—totally based upon arrests not even breath checks or random checkpoints. Biased—based upon enforcement priority law enforcement agency, department or individual officer. If done regularly, could actually cause lower drinking and driving and thus less ARMVC….”case of Random Breath Tests” Could be used as intermediate variable measure of “DUI enforcement activity”.

    11. Fatal Accident Reporting System Based upon detailed individual crash records from every state When possible BAC of any fatal driver or pedestrian is measured—considerable state variation. Data is cleaned and inconsistencies reported and usually corrected.

    12. FARS--Extent of BAC Reporting by State for Drivers in Fatal Crashes, 2004

    13. Table shows important predictor variables that cover crash, vehicle and driver level characteristics. Imputation is performed along Vehicle categories, i.e., the process for one vehicle category is performed completely independent of another vehicle category. Vehicle Categories are: Passenger Cars, SUVs, Minivans, other LTVs, motorcycles, Large Trucks, Nonoccupants, Miscellaneous vehicles (Buses, motorhomes, etc.).Table shows important predictor variables that cover crash, vehicle and driver level characteristics. Imputation is performed along Vehicle categories, i.e., the process for one vehicle category is performed completely independent of another vehicle category. Vehicle Categories are: Passenger Cars, SUVs, Minivans, other LTVs, motorcycles, Large Trucks, Nonoccupants, Miscellaneous vehicles (Buses, motorhomes, etc.).

    14. ARF Imputed BAC versus Final Reported BAC, 2001

    15. ARF Imputed BAC versus Final Reported BAC, 2003

    16. Details on FARS Imputation http://www.lifesaversconference.org/webfiles2006/utter.ppt)

    17. Advantages of FARS Focus on alcohol involvement of fatal drivers and pedestrians. Long historical files by state—useful for establishing tends and time series. Readily available over the internet or via data request. Based, where possible, on actual BAC measurement. Widely used in epidemiology, policy analyses, and program evaluation.

    18. Disadvantages of FARS Underestimate of alcohol-related crashes (even if ALL dead drivers and pedestrians are tested). Lack of full reporting by every state requires imputation. Analyses for regions, counties, or cities often lack statistical power to be useful…too few cases in low population areas.

    19. State Traffic Crash Records Available to qualified researchers and state statisticians/epidemiologists. Uses all available crash data not just fatal crashes—much larger numbers than FARS. Enable long time series to be developed which can be customized to the local situation and needs. Can be used to analyze trends and patterns over time.

    20. Police Reported “Had been Drinking” or “Alcohol-Involved” Available--Every state has such an item on its traffic crash form. Requires officer judgment at the scene of the crash—introduces bias in reporting. Does not provide separate validation. Has been shown to mirror other ARMVC data but is substantial underestimate.

    21. Surrogates from State Crash Data Single Vehicle Nighttime Crashes —includes factors associated with drinking and driving. Fatal Crashes —large number of these crashes are alcohol-involved (between 30-50%) Injury crashes —alcohol-involvement increases with severity.

    22. Single Vehicle Nighttime Crashes Drinking & Driving Single vehicle—associated with one driver, not multiple drivers, for cause. High drinking probability. Typically 8 pm to 4 am has highest number of drinking drivers. Fatal alcohol crashes highest between midnight and 3 am--FARS Most popular surrogate Produces greater number of cases for local analyses Increased alcohol-involvement if limited to weekend nights (Friday or Saturday) or Fatal crashes

    23. Fatal Crashes On average, fatal crashes have high likelihood of having at least one drinking driver or pedestrian involved. Limiting to nighttime crashes will increase alcohol-involvement probability. Fatal alcohol crashes highest between midnight and 3 am--FARS

    24. Injury Crashes Injury crashes—one in which at least one person is injured (but not killed). Injury crashes have higher association with alcohol-involvement than non-injury. Alcohol-involvement (percentage of crashes) increases as injury severity increases. Typically yields highest number of ARMVC. Limiting to nighttime or weekend nighttime increases percentage of alcohol-involvement.

    25. State Traffic Crash Data Disadvantages Special statistical analyses required. Surrogates developed since ideal measurement not available. Surrogates may lack “face validity”. Advantages Statistical power for small populations increased …more local cases. Alternative surrogates can be tested and compared for reliability. Widely used in policy studies and evaluation in published scientific papers.

    26. ARMVC Data and Purpose

    27. General Analytical Strategies for Evaluation Use long time series (quarterly or monthly) to test for prevention effects. Pre period (before prevention) can be compared to post prevention period. Can control for historical effects by using same data from another comparable localities or by using other indicators, e.g., daytime or non injury crashes. Use multiple surrogates to test—increases validity of inference of “effects”. Eliminates competing explanations.

    28. Suggested References Mounce, N., O. Pendleton, and O. Gonzales. 1988. Alcohol involvement in Texas driver fatalities. College Station: Texas Transportation Institute, Texas A&M University. PF Waller, FC Blow, RF Maio, EM Hill, K Singer, N Schaefer, “Crash Characteristics and Injuries of Drivers Impaired by Alcohol/Drugs”, Accident Analysis & Prevention, 29 (1997) pp. 817-827 Holder, H.D. and Wagenaar, A.C. "Mandated server training and reduced alcohol-involved traffic crashes: A time series analysis of the Oregon experience," Accident Analysis and Prevention, 26(1):89-97, 1994. Bernat DH, Dunsmuir WT, and Wagenaar AC., “Effects of lowering the legal BAC to 0.08 on single-vehicle-nighttime fatal traffic crashes in 19 jurisdictions.” Accid Anal Prev. 2004 Nov;36(6):1089-97. Heeren, T., Smith, R. A., Morelock, S., & Hingson, R. W. (1985). Surrogate measures of alcohol involvement in fatal crashes: Are conventional indicators adequate? Journal of Safety Research, 16(3), 127-133.

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