Over the past few years, the concept of "aggressive driving" has become a major public concern and a growing focus of highway safety programs. According to the National Highway Traffic Safety Administration (NHTSA), aggressive driving occurs when "an individual commits a combination of moving traffic offenses so as to endanger other persons or property." Accordingly, aggressive driving often includes a series of such offenses as following too closely, changing lanes without caution or signal, running a red light, or improper passing. A distinction is made between the traffic offense of aggressive driving and the criminal offense of road rage, defined as "an assault with a motor vehicle or other dangerous weapon by the operator or passenger(s) of one motor vehicle or precipitated by an incident that occurred on a roadway" (NHTSA, 2000, 2001).
Surveys of drivers in various jurisdictions have indicated that drivers believe aggressive driving is a major threat to their safety and a growing problem (RSM, Inc., 1997; McCartt et al., 1998; Preusser Research Group, 1998). In 1997, NHTSA conducted the first national survey on aggressive driving (Boyle, Dienstfrey, and Sothoron, 1998). Key findings of the survey included the following:
Various hypotheses about the causes of aggressive driving have been advanced. Experts at a symposium on aggressive driving, convened by NHTSA and the Federal Highway Administration (FHWA), pointed to traffic congestion as a major factor (NHTSA and FHWA, 1999). From 1985 to 1995 in the U.S., the number of registered motor vehicles increased 19 percent, the number of licensed drivers increased 12 percent, and total vehicle miles traveled increased 40 percent. Yet, roadway surface miles increased only 1.1 percent and the number of traffic enforcement officers declined (NHTSA, 2000). Psychologically-based hypotheses for aggressive driving include feeling endangered, watching other drivers break the rules, feeling the need to retaliate, and a culture of disrespect on the roadways (Goehring, 2000). Time pressures may also contribute to aggressive driving; in a survey of New York drivers, 41 percent of drivers reported that they drive more aggressively when they are late or in a hurry (McCartt et al., 1998).
Some states have responded to concerns about aggressive driving by enacting legislation; other states have determined that existing laws are sufficient to address serious violators of traffic laws. In 1998, Arizona became the first state to pass a law creating a specific aggressive driving offense. Other states, including Nevada, Delaware, Rhode Island, and Utah, also enacted legislation to provide for an aggressive driving offense. In 2000, 19 states introduced a total of 36 bills that addressed various aspects of aggressive driving (Savage, 2000).
Although some experts recommend various educational strategies for reducing unsafe driving behavior, enforcement of traffic laws remains the primary countermeasure used by communities to reduce speeding and other forms of unsafe driving. Based on three decades of developing and testing various programmatic strategies, programs of intensive enforcement, when combined with intensive public awareness efforts, have been shown to be effective in reducing unsafe driving behaviors. Official support and the involvement of community organizations further enhance success.
NHTSA's aggressive driving work plan includes the development of enforcement countermeasures and public information and education strategies to inform the public, law enforcement agencies, engineers, and the judiciary about the dangers of aggressive driving and possible solutions (NHTSA and FHWA, 1999). To support the development of "best practices" for implementation by communities (NHTSA 1998, 2000), NHTSA has sponsored aggressive driving enforcement demonstration projects in high traffic density urban areas. The primary objective is to determine whether highly publicized intensified enforcement of aggressive driving offenses, in states with aggressive driving laws, or of offenses generally associated with aggressive driving, in states without specific laws, results in positive changes in drivers' attitudes and behaviors. A second objective is to test the willingness, and the ability, of law enforcement officers to enforce a wide range of "aggressive driving type" violations in addition to speeding. A third objective is to test the feasibility and effectiveness of alternative public awareness and enforcement strategies, including the use of innovative technologies to detect aggressive driving actions. A fourth objective is to develop ways to obtain public and private sector support for a program to reduce aggressive driving. Finally, it is hoped that evaluations of the demonstration projects will further our understanding of how to define and measure aggressive driving.
On March 30, 1999, the City of Milwaukee launched "Aggressive Suppression" a six-month aggressive driving enforcement campaign. The program represented the first aggressive driving enforcement demonstration project funded by NHTSA. Through a strong community coalition, Milwaukee implemented a program that combined intensified general and targeted enforcement by the major enforcement agencies with efforts to educate the public about the dangers of aggressive driving and publicity about the heightened enforcement.
At least four considerations were key in NHTSA's determination that Milwaukee would be a suitable demonstration site. First, through the City's Traffic Safety Commission, Milwaukee had demonstrated a commitment to traffic safety by previously implementing comprehensive highway safety programs and numerous special traffic enforcement programs. In doing so, Milwaukee had gained experience in conducting a well-coordinated enforcement program involving the key enforcement agencies. Second, extensive historical crash and citation data were available to support the development of a targeted enforcement program. Third, Milwaukee's effort would complement a statewide aggressive driving program, "Let It Ride," implemented by the Wisconsin Department of Transportation. Finally, an evaluation component insured that lessons would be learned for other communities about what "worked and didn't work." In summary, the Aggression Suppression Program provided an opportunity to further understanding of how to define and measure aggressive driving and how to develop, implement, and evaluate community programs to reduce aggressive driving behaviors.
This report describes Milwaukee's Aggression Suppression Program and presents the results of a process and outcome evaluation of the program.