Relationship of Impaired Drinking Enforcement Intensity to Drinking and Driving on the Roads

Introduction: Principally, enforcement offers the greatest opportunity for reducing alcohol-impaired driving in the near future. However, enforcement of drinking and driving laws is not without cost, and it must compete against other law enforcement activities, especially given the current economic strain on local and state budgets. How much of a reduction in drinking and driving would be achieved by how much improvement in enforcement intensity?

Methods: We developed logistic regression models to explore how enforcement intensity (six different measures) related to the prevalence of weekend, nighttime drivers in the 2007 National Roadside Survey who had been drinking (blood alcohol concentration [BAC] > .00 g/dL), who had BACs > .05 g/dL, and who had illegal BACs > .08 g/dL.

Results: In our sample of 30 communities, drivers on the roads who were exposed to fewer than 228 traffic stops per 10,000 population aged 18 and older had 2.4 times the odds of being BAC positive, 3.6 times the odds of driving with a BAC > .05, and 3.8 times the odds of driving with a BAC > .08 compared to drivers on the roads in communities with more than 1,275 traffic stops per 10,000 population. Drivers on the roads in communities with fewer than 3.7 driving under the influence (DUI) arrests per 10,000 population had 2.7 times the odds of BAC-positive drivers on the roads compared to communities with the highest intensity of DUI arrest activity (>38 DUI arrests per 10,000 population).

Conclusions: The number of traffic stops and DUI arrests per capita were associated significantly with the odds of drinking and driving in these communities. This might reflect traffic enforcement visibility. The findings in this study may help law enforcement agencies around the country adjust their traffic enforcement intensity to reduce impaired driving in their communities. A logical next step in the research process will be to attempt to determine the thresholds where an increase in DUI arrests per capita, for example, significantly affects impaired driving. Are impaired driving crashes or impaired drivers on the roads significantly reduced if a law enforcement agency doubles its DUI arrest rate from 20 to 40 per 10,000 population? This kind of research could complement what we found in this study.