Traffic safety - alcohol ignition interlocks are effective while installed; less is know about how to increase installation rates

" Motor vehicle crashes involving alcohol-impaired drivers killed 10,322 people in 2012 and account for almost one third of all traffic fatalities annually. Ignition interlocks are one strategy states use to combat DWI. In 2012, MAP-21 established a grant program for states that adopt and implement mandatory alcohol ignition-interlock laws for all convicted DWI offenders. Funding authorization for this program expires at the end of fiscal year 2014. GAO was asked to review the effectiveness of ignition interlocks and NHTSA's implementation of the new grant program. This report discusses (1) what is known about ignition interlock effectiveness and (2) the extent to which NHTSA has assisted states in implementing ignitioninterlock programs, including the grant program. GAO reviewed 25 studies that analyzed relationships between ignition interlocks and DWI arrests and fatalities; interviewed NHTSA officials and reviewed reports about NHTSA's assistance to states; and interviewed representatives from safety-advocacy and research organizations, and officials involved with ignition-interlock programs from 10 states. The states were selected based on grant program qualification and the number of alcohol-impaired fatalities, among other factors. The information from these states is not generalizable. DOT officials reviewed a draft of this report and generally agreed with the findings. DOT offered technical corrections"