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The Effect of Police Enforcement on Roadway Safety

The Effect of Police Enforcement on Roadway Safety

University of Oregon

Synopsis: Decreased enforcement by troopers is associated with an increase in injuries and deaths on Oregon highways.


Community Need

Automobile accidents are the leading cause of death for Americans between the ages of 4 and 34, accounting for over 19,000 fatalities in 2003. Speeding is known to be one of the most frequent causes of driving fatalities. Damages from accidents costs approximately $230 billion per year in the US. One of the most common policies intended to increase roadway safety is police enforcement of speeding limits (through the use of fines, citations, and apprehension). However, the impact of this policy and whether it deters speeding or enhances roadway safety has not been studied in great depth.


In this paper, the authors study the deterrence effects of highway patrol officers on roadway safety. The authors identify the effect of a change in enforcement by studying a mass layoff (35%) of state police in Oregon in 2003 due solely to budget cuts.


Primary Research Question(S)

What deterrence effects does police enforcement have on roadway safety?

Research Design

In order to study how changes in police enforcement effect roadway safety, researchers analyzed the 2003 mass layoff (35%) of state police in Oregon. Researchers used several data sources from the time period 2000-2005. The Law Enforcement Officer Killed in Action (LEOKA) report of the Uniform Crime Reports, Census of Law Enforcement, and administrative records from Oregon, Idaho, and Washington provided information on state police enforcement levels. The Fatal Analysis Reporting System (FARS) of the National Highway Traffic and Safety Administration (NHTSA) provided data on the timing and characteristics of the universe of fatal car accidents in United States, and NHTSA also provided data on vehicle miles traveled (VMT). Researchers also utilized National Climatic Data Center data to construct and control for weather variables. Researchers used data from Washington and Idaho to form comparison groups.


The authors did not specify any limitations to the study.


Research Findings

The results indicate that a decrease in enforcement, defined by either troopers employed or citations given, is associated with an increase in injuries and deaths on Oregon highways. When compared to the rest of the United States, Oregon highway fatalities were estimated to have increased by roughly 5–6%, and 7–9% under dry weather conditions outside of city limits. Using Washington and Idaho as comparison groups, the layoff in Oregon is estimated to have increased highway fatalities by 12–14% , and highway fatalities under dry weather conditions by 19–26%. Likewise, average speeds and cited speeds both increased in the period after the layoff. The researchers also conducted a cost-benefit analysis and found the costs associated with injuries and fatalities outweighed any savings that resulted from the original budget cuts that reduced enforcement (i.e., the layoffs). Lastly, researchers found that Oregon would have experienced 2,302 fewer fatalities from 1979–2005 if the number of state police had been maintained at their 1979 levels.

Main Implications

Police enforcement is a critical deterrent to roadway speeding, which leads to injuries and fatalities. It is important to consider these effects when making budgetary decisions that endanger the jobs of troopers and law enforcement. The costs associated with roadway injuries and fatalities as a result of employment reductions likely outweigh any savings achieved by cutting jobs.


DeAngelo, G., & Hansen, B. (2014). Life and death in the fast lane: Police enforcement and traffic fatalities. American Economic Journal: Economic Policy, 6(2), 231-57.