In Potomac, Md., a man strikes a woman in the face after he bumps into her Jeep. And in Seattle, Wash., a driver shoots and kills a college student because the student could not disarm his anti-theft alarm.

This is road rage. One driver becoming angry at another driver over something he or she did is how Arnold P. Nerenberg, Ph.D., defines the phenomenon. And he has a theory about why it happens.
 

"There is something about the human psyche that makes us want to release our aggression on an anonymous other when we feel justified," said Nerenberg who's being called America's road rage therapist. Nerenberg is a clinical psychologist in Los Angeles County, a place where they have plenty of opportunities to experience traffic congestion and driving stresses.

It's difficult to get a handle on the scope of the problem. Some say road rage has become a catchall label that's being defined much too broadly, and there are a few studies done that are looking into this issue.

For example, Nerenberg believes people suffer from this disorder if they show road rage behaviors--ranging from making obscene gestures to brandishing or firing a weapon--two or more times a year.

Based on this criteria and interviews with 585 Southern Californians and Oregonians, he believes 53 percent of the population has a road rage disorder.

There's also a fuzzy line between aggressive driving and road rage. When Congress held a hearing into why seemingly ordinary people are going berserk on the roads, the head of the Department of Transportation (DOT) testified that aggressive driving (which includes weaving in and out of traffic and speeding) caused 29,000 of 42,000 traffic fatalities in 1996.
 

Whether it's defined broadly--as any display of aggression by a driver--or used to refer to more extreme acts of violence, road rage is being recognized as more of a problem.

An average of at least 1500 people are injured or killed each year in the United States as a result of "aggressive driving," according to a AAA Foundation fo Highway Safety study. That study analyzed 10,000 police reports and newspaper stories about traffic incidents that led to violence and concluded that, while many of the aggressive drivers were young men with criminal records, others were average citizens of all ages, women included, who just snapped.

Nerenberg has identified five traffic situations that cause people to overreact and explode when these are combined with other factors in their lives, such as illness, alcohol, drugs, or arguments.

Here are the triggers, along with solutions suggested by Nerenberg and Sgt. Pam Marshack with the Delaware State Patrol, a specialist in women's safety:

Number one on Nerenberg's list is endangerment, which includes cutting off another vehicle, tailgaiting (driving closely behind an other vehicle), or causing a fender bender. "You don't want to endanger somebody by tailgaiting or cutting them off," Nerenberg said.

Maintaining a safe distance from the vehicle in front of you will go a long way toward avoiding many of these problems. And use your turn signal to change lanes.

"People are lax about turn signals," said Marshack. "We have to drive like we want other people to drive."

No one wants to cause a fender bender, but if it happens, Nerenberg warns that latent road ragers can become very violent.

Nerenberg and Marshack recommend staying in the car with the door locked and the window open a crack to allow you to talk to the other driver. Next, call the police if you have a cellular phone. If the other driver is hostile, there are several things you can do.

"Even if you haven't made the call yet, have the phone in your hand and say, 'I'm on the phone with the police' as a deterrent," Marshack said. "If they are thinking of smashing your window or saying a few choice words, maybe they'll cool their heels a little bit."

"If the other person becomes hostile and comes over and starts banging on your window, drive away," Nerenberg said.

"You always want to obey the law, but there are judgment calls that you have to make. Say, 'I know where there's a police station, I'm going to drive there and we can talk about it.' "

Marshack agrees. "Anytime you have any reason to believe you're in danger, I suggest you leave. Or if you can't because your car won't move or you're stuck in traffic, blare the horn. That should startle the person into behaving or get the attention of good people."

The second thing guaranteed to make road ragers erupt is slowing them down in traffic, Nerenberg said. One example is blocking the left, or passing lane. "If you're in the left lane going too slowly, pull over to the right," he said.

The third trigger is taking a parking spot someone was about to pull into. "If by mistake you've taken somebody's parking spot, and they let you know that, just apologize, pull out, and let them have it," Nerenberg said. "You may think you're right, but don't get into an argument."

Fourth on the list is showing anger, Nerenberg said. Road ragers can react violently when someone directs anger at them, said Nerenberg.

"If someone shows aggression and they flip you off or yell at you, don't yell back. That will just escalate it, which could get you killed. People have been rammed to death or shot. You don't want to go into road rage yourself; you don't want to retaliate."

Nerenberg and others who have studied the issue say to avoid eye contact with someone who is being belligerent because it can be interpreted as a challenging gesture. "It's an animal thing," said Nerenberg. "It sets up an animal aggression and exacerbates the problem."

Finally, some potential road ragers get angry when they believe another driver is breaking the rules of the road. "Some of the people who get most angry are themselves courteous drivers," Nerenberg said. "And when someone else isn't, that makes them really ticked."

One such scenario is in a construction zone where two lanes narrow into one and two lines of traffic have to merge, Marshack said.

"Don't wait until the last minute to cut over and pass a line of cars that have already moved over. You aren't playing by the rules like everybody else. Be a considerate driver.

"It goes back to doing unto others as you would have them do unto you. Drive the way you wish everyone else would drive."