Trends in blood alcohol concentration levels of night drivers. Paper presented at the 53rd Annual Meeting of the Highway Research Board HRB, Washington, D.C., January 1974.

The influence of the Fairfax County alcohol safety action project on the B.A.C.'s of drivers at night is discussed. Data were taken before and 9 months after the start of the project. Significantly higher percentages of drinking drivers were found in the after survey, with a slight reduction in B.A.C. above 0.10%. An index of accident probability that revealed dramatic reductions in accident probability for late night hours on weekends was calculated.