An Analysis of Ultimate Performance Measures to Determine Total Project Impact of the Fairfax Alcohol Safety Action Project: Progress Report #4

Report No: 77-R11

Published in 1976

About the report:

The Fairfax ASAP, one of 35 federally funded alcohol countermeasure projects designed to attack the problem of drunken drivers on the highways, was implemented at the community level in January 1972. This report summarizes the results of data obtained to measure the project's impact on the selected ultimate performance indicators at the end of the fourth year of project operations, 1975. Data for 1975 indicate a significant change in trends of several ultimate performance measures in the Fairfax ASAP area. There was a significant decrease in the number of personal injuries, personal injury crashes, fatal injuries, fatal injury crashes and property damage crashes from what would have been predicted by linear regression analysis based upon trends established over the past ten years. These changes are significant at the 95% confidence level. No such change was evident in the control community, Henrico County, in any of the performance categories except property damage crashes. (The reduction in property damage crashes in both Fairfax and Henrico was likely the result of a change in accident reporting criteria, and probably does not reflect a change in the incidence of property damage accidents.) While another performance indicator, the average blood alcohol concentration of drivers in the ASAP area showed little change during the 1972-1974 period, the mean BAC for 1975 was the lowest in recent years. The mean BAC for fatally injured drivers was .126% in 1975, compared to the previous six year low of .148% in 1973. The average number of fatally injured drivers with positive BAC's during the operational period of the ASAP (1972-1975) was virtually identical to the pre-ASAP average. The average BAC levels for drivers arrested for driving while intoxicated (DWI) but not involved in crashes declined from .19% in 1972 to 16% in 1975. While this decline might be attributable to a reduction in the "pool" of intoxicated drivers, it should be noted that the presumptive limit for drunk driving was changed from .15% to .10% in 1972. Therefore, intuitively, the average BAC should be lower since the pool of drivers subject to arrest for DWI was increased on the lower end of the BAC scale. An analysis of BAC distributions in quarter 16 versus those in quarter i confirms that a statistically significant change occurred. BAC levels were significantly lower in quarter 16 than in quarter 1. In terms of the cost benefit analysis, the actual societal costs resulting from accidents in Fairfax during 1975 were significantly lower than the projected costs based on pre ASAP trends.

Disclaimer Statement:The contents of this report reflect the views of the author(s), who is responsible for the facts and the accuracy of the data presented herein. The contents do not necessarily reflect the official views or policies of the Virginia Department of Transportation, the Commonwealth Transportation Board, or the Federal Highway Administration. This report does not constitute a standard, specification, or regulation. Any inclusion of manufacturer names, trade names, or trademarks is for identification purposes only and is not to be considered an endorsement.

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Jeffrey A. Spencer

Last updated: January 28, 2024

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