Abstract
The efficacy of drinking-driving countermeasures can be assessedin several ways, including reported changes in attitudes and behavioral intent as well as changes in crash rates. However, few studies have examined the changes in actual drinking-driving behavior. A method of surveying the blood alcohol concentrations (bacs) of drivers, without either police intervention or disruption to traffic flow, was developed in south australia. This method, which has been used successfully to test approximately 50, 000 drivers, is described in detail