Research on Control and Prediction of Alcohol Impaired Driving with Ignition SAE International Meeting February 6, 2009 Interlocks Paul R. Marques, Ph.D. Senior Research Scientist marques@pire.org
Important Distinction Interlock Devices the hardware Early devices were non-specific Tagucci semiconductors, currently most are alcohol specific fuel-cell devices. Interlock Programs the regulations Laws (court or licensing programs), sanctions, reporting protocols, information flow, treatment links, consequences etc
Four Key Elements (of alcohol interlock devices) (1) an alcohol sensor that prevents engine starts if breath alcohol is detected above some minimal level such as BAC.02 g/dl (e.g.,.02%) (2) a running retest feature, which requires at least one retest after the car has started, typically retests are every 15 to 45 minutes while driving (3) a tamper-detecting installation in the engine, which requires inspection every 30 to 60 days to preclude bypass wiring (4) a data-recording system that logs the time of all BAC tests, starts, stops, procedural violations or circumvention attempts.
Topics Today Interlock Penetration / Growth Effectiveness Evidence Patterns in the Data: Drinking, Vehicle Use, High Risk Offenders First Offender Risks
Events in interlock history 250000 200000 150000 California law Alberta law NHTSA Model Specs O 100000 ICADTS Interlock WG 50000 0 FL program MADD Campaign -50000 Year 1987 1989 1991 1993 1995 1997 1999 2001 2003 2005 2007 2009 Voas et al. AB study Beck et al., MD study
FBI estimate of 1.4 million DUI arrests annually. 1400000 1,4 million DUI arrests annually (in 2007: FBI) MADD Campaign to End Drunk Driving will seek 600,000 more interlocks in 5-7 years. What might accomplish this? First and multiple offenders, More enforcement, Better monitoring, Program tied to the BAC tests and other objective indicators, Stronger (less appealing) alternatives for the opt outs 1200000 1000000 800000 600000 400000 200000 0 1986 1990 Total Convictions? MADD projection 1994 1998 2002 2006 2010 2014
New Mexico interlock rate represents 49% of all convicted DUI offenders there
Topics Today Interlock Penetration / Growth Effectiveness Evidence Patterns in the Data: Drinking, Vehicle Use, High Risk Offenders First Offender Risks
Effectiveness We want to reduce alcohol crashes, crash injuries and fatalities but we mostly measure drunk driving recidivism as the target outcome measure. Arrest/conviction for DUI recidivism is a proxy for alcohol crashes. There are ~160+ DWI arrests for each fatality in which a driver had a BAC >=.08 g/dl. Soon there will be enough interlocks to estimate the extent of alcohol crash risk reduction.
New Mexico
Willis et al., 2004 Interlock ON 13 study samples Maryland RA study OVERALL =.36 (i.e., 64% reduction)
Willis et al., 2004 Interlock OFF 10 study samples Maryland RA study
Topics Today Interlock Penetration / Growth Effectiveness Evidence Patterns in the Data: Drinking, Vehicle Use, High Risk Offenders First Offender Risks
Interlocks: first and multiple offenders give median 6-8 BAC tests every day* 1100 1000 900 800 700 600 Quebec BAC Tests per day * 7x 365 = 2555 tests/year Note: Start-up tests are about half of all tests Frequency 500 400 300 200 100 0 32.0 30.0 28.0 26.0 24.0 22.0 20.0 18.0 16.0 14.0 12.0 10.0 8.0 6.0 4.0 2.0 0.0 Std. Dev = 4.63 Mean = 8.8 N = 9176.00
Predicting Future DUI with the RATE of Interlock BAC test positives 24 Mo. AFTER INTERLOCK N=720 Offenders in Each Bar Data from Marques, Voas, Tippetts (2003) Addiction, Quebec Prediction Study Support from NIAAA top 40% DURING INTERLOCK BAC Rate.02%
0.200 0.150 0.100 0.050 Recidivism Rates During and After Interlock by RATES of Failed BAC tests (NM) Total N~5000 ~ 500 / line Zeros Decile 5 Decile 6 Decile 7 Decile 8 Decile 9 Decile 10 Total top 30% 0.000 6mo 12mo 6mo 12mo 18mo 24mo DURING Interlock AFTER Interlock
How Predictable are People? Québec BAC.02% Weekday morning 7-8 am All BAC tests Alberta
Morning high BAC most frequent 7-8 am Weekdays - Max positive BAC Confirmed in 4 jurisdictions (TX,AB, QC, NM) based on more than 40 million BAC tests 1.00 0.80 0.60 0.40 0.20 0.00 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 Hour of Day Quebec All Tests Quebec Tests>=.02% Alberta All Tests Alberta Tests >=.02 Texas All Tests TX tests>.02%
Recidivism Rates During and After Interlock by RATES of Failed Morning BAC tests 0.200 top 30% 0.150 0.100 Zeros Decile 7 Decile 8 Decile 9 Decile 10 Total 0.050 0.000 6mo 12mo 6mo 12mo 18mo 24mo DURING Interlock AFTER Interlock
Z scores 10 alcohol biomarkers by 3 groups of failed interlock BAC Alberta 2008 Low None High *** *** *** *** *** *** ns * *** *** *** P<.0005 top 20.5% of fail rate
Topics Today Interlock Penetration / Growth Effectiveness Evidence Patterns in the Data: Drinking, Vehicle Use, High Risk Offenders First Offender Risks
First and Multiple Offenders by the 3 Interlock Risk Groups None Low High
What about First Offenders? Alcohol Mentions/1000 drivers in Maryland 5 million licensees The distinction between first and second offender is small compared to first and nonoffender. A first offender has ten times more alcohol mentions than a non-offender. A second offender has only 25% more than a first time offender. 70 60 50 40 30 20 10 0 10x higher 0 1 2 3 Prior DUI Rauch et al., TRB 2002
Similar evidence from New Mexico % Re-arrested within 3 Years 25% 20% 15% 10% 5% 0% 5x higher None 1st 2nd 3rd 4th 5th+ Conviction Number in 2003 Relative to Non-Offenders, First Time DUI Offenders are 5x more likely to be arrested within 3 years for DUI
If attainable: why alcohol sensing in all cars would be useful to road safety Interlock use by high risk drinking drivers is low Risk of arrest is low about 600-1000 episodes of impaired driving for each arrest (1.4 million arrests/yr) Estimate ~ 60-65% of arrestees convicted Of those convicted and eligible (only 5-50% install interlocks depends on state) Of those who install, about 30% rack up high rates of failed BAC tests (and/or procedural violations) Typical installation is 6-18 months Those who have high fail rates are persistent drinking drivers: re-arrest rate in 2 years (about 15% - 25) Most who install use the interlock car appropriately but they may not be the highest risk offenders
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