Warning Drivers About Potential Congestion as a Means to Reduce Frustration-Driven Aggressive Driving

Abstract

Objective: This research was conducted to examine the consequences of forewarning drivers about impending congestion on aggressive driving behavior. Some have argued that aggressive driving stems from frustration experienced on the roadway (often due to congestion), and that by warning drivers about congestion, frustration, and consequently aggressive driving, can be reduced. Methods: The study employed an experimental design, where participants (whose dispositional driver anger was measured using the Driver Anger Scale) were instructed to operate an instrumented vehicle along a prescribed route containing construction. Participants were randomly assigned either to receive a warning about the construction or to receive no warning about the congestion. Measures of aggressive driving behavior were extracted from video (shot from a camera hidden behind the vehicle's license plate) and from an ongoing accelerometer. Results: A total of 49 participants completed the study. Analyses of combined measure of aggressive driving behavior data revealed a statistically significant main effect for dispositional driver anger (with participants scoring higher on the scale actually driving more aggressively), as well as interactions between driver anger and forewarning. Accordingly, forewarning about potential congestion reduced aggressive driving behavior for participants high in dispositional anger but increased aggressive behavior for participants who were low on dispositional anger. Conclusion: Some of the results—particularly the increase in aggressive driving among participants low in dispositional driver anger who were warning about congestion—were unexpected. The interaction effect suggests that the strategy providing warnings about upcoming congestion will not necessarily reduce frustration among all drivers.