The National Academies

NCHRP 17-67 [Active]

Identification of Factors Contributing to the Decline of Traffic Fatalities in the United States

  Project Data
Funds: $299,738
Staff Responsibility: Mark S. Bush
Research Agency: University of Michigan
Principal Investigator: Daniel Blower, PhD and Carol Flannagan, PhD
Effective Date: 9/22/2014
Completion Date: 6/30/2017

According to data from the National Highway Traffic Safety Administration, the United States has experienced a steady decline in the number of highway fatalities since 2005, with a dramatic decline beginning in 2007. Even with the reduction in deaths on our nation’s roads, highway fatalities and serious injuries remain a significant threat to public health. While a significant decline in fatalities from 2005 to 2011 occurred, early data from 2012 shows an increase. With the passage of reauthorization of federal transportation funding, Moving Ahead for Progress in the 21st Century (MAP-21), states are required to increase focus on safety performance targets, especially those involving fatalities and serious injuries. Decision makers need to understand how various factors have affected highway fatality trends, continue to implement the programs that make the best use of limited funds and personnel, and make the most progress toward meeting performance targets. Various explanations have been offered to account for the significant reduction in crashes in recent years. Such factors as increased safety belt usage, safer vehicles, better roads, increased funding for safety infrastructure improvements, the economic downturn, changes in teen licensing laws, enhanced enforcement efforts, etc., have been identified as possible contributors to the downward trend in crashes. To date, no comprehensive analysis of crash data and contributing crash factors has been performed to determine the relative impact of various factors. Such an analysis would seek correlation between crash types and multiple factors such as levels of highway spending, installation of corridor-wide crash countermeasures, levels of highway enforcement, levels of funding for educational campaigns targeting driver behavior, average percent expenditure on safety features in automobiles, increase in highway safety related legislation, economic indicators, etc.  Without a comprehensive study of the crash data and the possible contributing factors creating the decline in crashes, it is difficult for highway safety professionals to know where best to direct resources. Research is needed to provide information that will help optimize the allocation of safety resources, especially within the recent years where the decrease in fatalities has not been so dramatic. Such research will assist states in determining where to most effectively apply their capital, operating, and human resources to continually reduce fatalities.


The objective of this research is to provide a multidisciplinary analysis of the relative influence of the types of factors that contributed to the recent national decline in the number of highway fatalities and rates in the United States. This research will assist transportation agencies and other safety stakeholders in optimizing resource allocation and strategic decision making to improve safety.

STATUS: Completed; To be published as an NCHRP research report 928.

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