Type of Problem Being Addressed
General Description of the Problem
The problem of aggressive driving appears to be increasing in seriousness. While there is great variance in the estimates of the problems extent, perceptions of both law enforcement and drivers is that the phenomenon is becoming more prevalent. As a result, people are experiencing driving as an increasingly dangerous activity:
In the United States, the Surface Transportation Policy Project found that aggressive driving is a factor in about 56 percent of all fatal crashes.2 The data were extracted from the Fatality Analysis Reporting System (FARS) records using a broad set of contributing factors, excluding drinking and driving but including most traffic violations without further interpretation. A more careful analysis of the data elements suggests that the percentage is substantially overstated (e.g., less than 25 percent of cases coded as speeding showed a speed in excess of the speed limit, and more than 60 percent of those involved only one vehicle).
On the other hand, traffic safety experts at a workshop on aggressive driving held in Washington, D.C., in November 2000, and later various committees of the Transportation Research Board, arrived at a consensus as to what constitutes the problem. The elements included the following:
Specific Attributes of the Problem
Two studies were conducted in the United Kingdom and published by the AAA Foundation for Traffic Safety (Connell and Joint, 1997). In one study, conducted by the Automobile Association in Great Britain in March 1995, British motorists indicated that the following actions, committed by both others and the surveyed motorists themselves, were considered to be aggressive driving:
In addition to the results reported above, this study also found that
The clear association between levels of anger and displays of aggressive driving suggests that younger drivers and male drivers would have a higher probability of displaying the above behaviors. Experience gained from focus groups and driver-improvement classes operated by the Northwestern University Center for Public Safety (Wark, 2000) indicates an especially high probability for younger male drivers to express feelings of anger related to driving. Additionally, their enrollment in driver-improvement classes indicates that young male drivers have the highest probability of being cited for aggression-related offenses.
The frustration-aggression approach suggested by researchers such as Shinar (1998) has the advantage of allowing for a conceptual relationship between the driving situation and the expression of anger by the individual driver. The basic assumption here is that drivers, when exposed to congestion and other frustrating situations, will experience increasing levels of aggression. The approach has received much support (Hauber, 1980; McDonald and Wooten, 1988; Kenrick and MacFarlane, 1986; Deffenbacher et al., 1994; Novaco 1992). Therefore, addressing drivers without correcting underlying driving-related environmental issues also may not be effective.
Another important attribute of the problem is the specific characteristics of the type of driving done by the individual. Ultimately, the likelihood that a given individual will display aggressive driving is a joint probability of their personal characteristics and the characteristics of a particular driving situation. Thus, there could exist a driving situation so nonstressful that it would likely engender aggressive driving only in a person with a great amount of personal anger, and another that could be so stressful that even the calmest person could begin to display aggression.
Aggressive driving is a contextual violation. The two major components of the context are the drivers (1) physical and psychological state (background and current condition) and (2) roadway environment. The type of aggressive driving displayed in a given area will in part also be a function of the setting. Most approaches to aggressive driving have occurred on controlled access roads. Perhaps this is why the role of speeding in aggressive driving has been emphasized. However, the most commonly noted aggressive behaviors involve drivers traveling faster than others, traveling well below the posted limit, or frequently changing lanes or tailgating. An extension of the concept to driving on surface streets is required. Urban areas with high periodic traffic and heterogeneous mixes of vehicle sizes, pedestrians, and bicycles are especially important to address. In such an environment, the operational definition of aggressive driving would change from something focused upon speed to violations involving turning, yielding, traffic control devices, and lane maintenance.
Efforts to Address the Problem
Most driver-directed programs referenced to date appear in NHTSAs Aggressive Driving Enforcement Strategies for Implementing Best Practices (2000).3 These programs generally have addressed aggressive driving through specific traffic-enforcement programs. Some agencies have reported program success measured by a reduction of crashes. With few exceptions, programs reporting success also have applied intensive traffic law enforcement aimed at all traffic law violations. Past literature has indicated that such programs can be effective (selective traffic enforcement programsor STEPsremain a recommended approach to reducing crashes at targeted locations). However, other research, such as that by B. J. Campbell in North Carolina (1978) and that by Dart and Hunter (1976), had examined enforcements halo effect and found it limited in time and space. Moreover, duration of these programs is limited because most police agencies do not have sufficient personnel for long-term maintenance. One of the few agencies reporting success through other outcome measures was Milwaukee,4 where education and enforcement are combined and the effort directed toward specific targeted violations.
No effort has explicitly addressed the engineering elements related to aggressive driving, even though traffic safety professionals recognize that the driving environment plays a role in driver behavior. There is an apparent link between aggression and frustration, and the driving environment often is a frustrating one. There remains a need to identify and correct, where possible, elements that can lead to frustration (e.g., uncoordinated traffic signals or lack of accurate information regarding the causes of traffic delays).
This guide suggests several strategies to address the problems. These strategies combine the elements of enforcement, education, and engineering. With few exceptions, programs depending only on one of these elements are not likely to be successful.
1 Aggressive Driving and the Law: A Symposium. 1999.