How intoxicated are drivers in the United States? Estimating the extent, risks and costs per kilometer of driving by blood alcohol level

This study develops and applies an algorithm with international applicabili ty for estimating vehicle kilometers (kms) driven by blood alcohol level (B AL) from police crash report data. In the United States, an estimated one i n 120 kms was driven with BAL greater than or equal to 0.10% in 1992-1993. The ratio increased to 1 in 7 kms driven on weekend evenings. The estimated cost per vehicle km driven with BAL greater than or equal to 0.08% was $3. 40 compared to $0.07 per sober km. Males, those age 21-29 and those driving between 22:00 and 04:00 had the greatest percentage of driving with BAL gr eater than or equal to 0.08%. These estimates are computed, in part, from e arly 1960s data on crash odds by driver BAL and assume crash odds by BAL re lative to sober do not vary with driver age and sex. Preliminary investigat ion indicates that the method provides reliable estimates of alcohol-positi ve kms from roadside surveys at night, but seems to over-estimate high-PAL kms. Direct field validation is highly desirable. (C) 1999 Elsevier Science Ltd. All rights reserved.