An Analysis of Ultimate Performance Measures to Determine Total Project Impact of the Fairfax Alcohol Safety Action Project: Progress Report No. 5, January 1, 1976 to December 31, 1976

Report No: 77-R59

Published in 1977

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 data obtained to measure the project's impact on the selected ultimate performance indicators at the end of the fifth year of project operations, 1976. Data for 1976 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 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. Another performance indicator, the average blood alcohol concentration of drivers in the ASAP area, showed little change during the 1972-1974 period. While the mean BAC for 1975 was the lowest in recent years, this figure increased again to 0.157% in 1976. The average number of fatally injured drivers with positive BAC's during the period of the ASAP (1972-1976) 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 0.1% in 1972 to 0.17% in 1976. 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 0.15% to 0.10% 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 20 versus those in quarter 1 confirmed that a statistically significant change occurred. BAC levels were significantly lower in quarter 20 than in quarter 1. In terms of the cost benefit analysis, the actual societal costs resulting from accidents in Fairfax during 1976 were lower than the projected costs based on pre-ASAP trends. This is the second year that the actual and projected costs were significantly different. Savings realized during 1976 were between $254 thousand and $21 million, with total savings over the life of the project being on the order of $40 million. No such cost savings were evidenced in the control site, Henrico County. While these data are encouraging, caution should be expressed over two confounding factors. The year 1971 was an extraordinary one in Fairfax for fatal crashes. Hence, the trend line for 1972 through 1974 was influenced by the large number of crashes in 1971. Reductions in fatal crashes and fatalities in 1972 and 1978 may reflect a regression to the mean. The second confounding factor was the effects of the energy crisis, which could not be adequately compensated for because all of the effects are not known. While the impact of the nationwide 55 mph speed limit is not as influential as in 1974, there may be savings attributable to the energy shortage figured into the total cost savings.

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.


  • Jeffrey A. Spencer, Cheryl W. Lynn

Last updated: January 28, 2024

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